Nbde Combined Qs

Front 1

A 1-year-old child is expected to have erupted which of the following primary maxillary and mandibular teeth? 1. lncisors and canines 2. lncisors and first molars 3. Central incisors and canines 4. Mandibular central and lateral incisors and maxillary central incisors

Back 1

The correct choice is 2= INCISORS AND FIRST MOLARS. A 12-month-old child generally has all of the primary incisors and first molars. The primary mandibular central incisors erupt at 6 months, the mandibular laterals at 7 months, the maxillary centrals at 7-12 months, the maxillary laterals at 9 months, and the maxillary and mandibular first molars at 12 months, although the maxillary first primary molar may not erupt until about 14 months. Choices 1 and 3: A 1-year-old should have all of the primary incisors, but the cuspids do not & erupt until later: the mandibular cuspid at 16 months and the maxillary cuspid at 18 months. Choice #4: All of the teeth listed, which were the mandibular centrals and laterals and maxillary centrals, should be present in a 1-year-old, but so should the maxillary laterals and first primary molars. So, once again, the correct choice for question is 2.

Front 2

A 1-year-old child is expected to have erupted which of the following primary maxillary and mandibular teeth? 1. lncisors and canines 2. lncisors and first molars 3. Central incisors and canines 4. Mandibular central and lateral incisors and maxillary central incisors

Back 2

INCISORS AND FIRST MOLARSThe correct choice is 2. A 12-month-old child generally has all of the primary incisors and first molars. The primary mandibular central incisors erupt at 6 months, the mandibular laterals at 7 months, the maxillary centrals at 7-12 months, the maxillary laterals at 9 months, and the maxillary and mandibular first molars at 12 months, although the maxillary first primary molar may not erupt until about 14 months. Choices 1 and 3: A 1-year-old should have all of the primary incisors, but the cuspids do not & erupt until later: the mandibular cuspid at 16 months and the maxillary cuspid at 18 months. Choice #4: All of the teeth listed, which were the mandibular centrals and laterals and maxillary centrals, should be present in a 1-year-old, but so should the maxillary laterals and first primary molars. So, once again, the correct choice for question is 2.

Front 3

A branch of which of the following cranial nerves to the tongue may be anesthetized during administration of an inferior alveolar block? 1. V 2. VII 3. IX 4. XII

Back 3

VThe correct answer is choice 1. Let's review the cranial nerves to the tongue. Firstly, all intrinsic and extrinsic tongue muscles receive motor innervation from the hypoglossal nerve cranial nerve XII except the palatoglossus which is innervated by the pharyngeal plexus. The regular sensation of the anterior two-thirds of the tongue is provided by the lingual branch of the mandibular division of the trigeminal, cranial nerve V. Taste sensation of the anterior two-thirds of the tongue is provided by the chorda tympani, a branch of the facial nerve, cranial nerve VII. Taste and regular sensation of the posterior one third of the tongue is provided by the glossopharyngeal nerve, cranial nerve IX. It is the lingual nerve, a branch of the cranial nerve V, which is usually anesthetized during an inferior alveolar nerve block. Remember that this is the nerve block used when performing procedures involving mandibular teeth. When entering and leaving the area of the inferior alveolar nerve, some anesthetic will be deposited close to the lingual nerve, anesthetizing it also. So the correct answer to question is choice 1

Front 4

A deep invagination of the lingual pit in a maxillary lateral incisor can be called A. dilaceration B. fusion C. concrescence D. anodontia E. dens in dente

Back 4

DENS IN DENTEThe correct answer is choice E. The term "dens-in dente" refers to the"tooth within a tooth" appearance on radiograph of a lateral incisor with a deeply invaginated lingual pit. The pit may have the size and shape of a small tooth. Dilaceration refers to a sudden change of direction of a root. Fusion refers to the joining of two teeth by dentin. Concrescence is the joining of two teeth by cementum. Anodontia refers to the lack of development of all teeth.

Front 5

A developmental abnormality in which all teeth are absent is A. Microdontia B. Oligodontia C. Anodontia D. Exodontia E. Odontoma

Back 5

ANODONTIAThe correct answer is choice C. Anodontia is the absence of formation of all teeth. This may be due to a variety of genetic, metabolic or hormonal problems. Microdontia refers to the presence of teeth markedly smaller dentin than normal size. Oligodontia refers to the absence of many, but not all teeth. A few missing teeth are sometimes referred to as hypodontia. Supernumerary teeth can be referred to as hyperdontia. Exodontia is the procedure of removing teeth. Odontoma is a benign tumor of tooth tissue (enamel, dentin, cemetum etc.)in multiple tooth-like form (compound odontoma) or non-descript masses (complex odontoma).

Front 6

A hypoplasia of primary teeth which is limited to the incisal thirds of incisors, to the incisal tips of canines, and to the occlusal portions of molars, suggests which of the following? A. Tetracycline medication in early life B. Excessive fluorides in the drinking water C. A metabolic disturbance during the prenatal period D. A metabolic disturbance during infancy and the early childhood periods

Back 6

A METABOLIC DISTURBANCE DURING INFANCY AND THE EARLY CHILDHOOD PERIODSThe correct answer is choice C. Hypoplasia involves poor development and calcification of teeth. It can be caused by trauma or disease during a stage at which developing teeth are calcifying. Tetracycline staining will cause discoloration of teeth, and is caused by a mother taking tetracycline during pregnancy, with tetracycline being incorporated into tooth structure. It is not, however, hypoplasia. Fluorides do not cause hypoplasia either. Excess systemic fluoride well beyond the recommended lppm can cause fluorosis, a discoloration of enamel. So our choice is either C or D, depending on when incisal edges of primary incisors, canines and molars are calcifying. It turns out that they all begin calcification in utero between 4-6 months. A variable amount of crown enamel is complete by birth, and the rest shortly thereafter. Remember that incisal edges calcify first.

Front 7

A mandibular canine differs from a maxillary canine in which of the following? A. It is longer. B. It has a less pronounced cingulum. C. The crown is approximately the same length. D. It has a cusp tip more nearly centered mesiodistally when viewed from the facial.

Back 7

IT HAS A LESS PRONOUNCED CINGULUMThe correct answer is choice B. In general, the mandibular canine is smaller in all respects. Its cingulum is less pronounced, and the tooth crown appears to be somewhat assymetrical, with the mesial section of the facial area higher and narower than the distal. The distal section of the facial view looks somewhat bulbous and extends out farther. The mesial height of contour is also higher than the distal.

Front 8

A mandibular primate space is usually found in the primary dentition between 1. central incisors. 2. central and lateral incisors. 3. lateral incisor and canine. 4. canine and first molar. 5. first and second molars.

Back 8

CANINE AND FIRST MOLARmolar. The maxillary primate space is found between the maxillary primary lateral incisor and canine. The primate space can occur in all other primates. When present, it usually allows the erupting mandibular first permanent molar to push forward and cause closure of the primate space. Then, the erupting maxillary first permanent molar can supposedly erupt directly into a class 1 "normal" molar relationship. If the primary dentition is crowded without spaces, the permanent first molars generally erupt end to end and the mandibular permanent molar cannot shift forward into a class 1 molar relationship until the primary mandibular second molar is replaced by the smaller permanent mandibular second bicuspid. This is referred to as a late mesial shift.

Front 9

A mental foramen would be found on x-ray closest to the root of which tooth? A. #19 B. #14 C. #29 D. #22 E. #4

Back 9

#29The correct answer is choice C. The mental foramen carries the mental nerve and artery through the mandible onto the skin overlying the mandible from the midline to the first premolar area. It also inervates buccal soft tissue and periosteum in the same area, as well as portions of the lower lip. Anesthetic is sometimes injected near the mental foramen to obtain anesthesia of these soft tissues. It is usually not possible to anesthetize teeth with a mental nerve block. The foramen is seen on x-ray as a lucent oval or circle most often near the apex of the mandibular second premolars (#20 and #29). It is possible in some cases to confuse the foramen with periapical pathology. Sometimes the foramen may be found slightly more mesially, toward the first premolar.

Front 10

A normal seven-year-old child will have how many teeth? A. 20 B. 22 C. 24 D. 26 E. 28

Back 10

24The correct answer is choice C. Fortunately, we do not really need to know here about replacement of deciduous teeth by permanents. At age seven, some of the primary incisors will have been replaced and some not. However, since there is a one-to-one replacement, it doesn't matter-if primaries or permanents are present. What is important is that the child has 20 primary teeth and that number of original tooth positions does not change as they are replaced. Only new teeth erupting distal to the original 20 will increase the total number. In this case, we expect that the four permanent first molars should erupt by about age six; therefore, four more than the original 20 teeth should be present, 24.

Front 11

All of the following are true of primary teeth, as compared to permanent teeth EXCEPT: A. Primary teeth are whiter in color B. Primary teeth have a smaller ratio of crown to root length. C. Primary teeth have a smaller ratio of mesial-distal width to crown height D. Primary molars have a smaller root trunk, relative to total tooth size E. Primary second molars closely model the anatomy of permanent first molars

Back 11

PRIMARY TEETH HAVE A SMALLER RATIO OF MESIAL-DISTAL WIDTH TO CROWN HEIGHTThe correct answer is choice C. The question reviews basic qualities or "set characteristics" of primary versus permanent teeth. In general, primaries are smaller than their permanent counterparts. They have the appearance of having very short crowns, because their crown is short, relative to their root size (small crown to root ratio). They also have the appearance of having "squat" crowns. This means that the crowns are flat, that is, they are relatively wide, but short in height (mesialdistal width to crown height ratio is LARGE. Primary molars have a very small root trunk, relative to the root trunk of the permanents. The root trunk is the area of combined root tissue. It is small in the primaries because that area is taken up by the developing permanent premolar crowns. Primary second molars are noted for their uncanny resemblance to permanent first molars (except in overal size).

Front 12

As compared with permanent teeth, the crowns of the primary teeth are A. larger. B. more bulbous and constricted. C. about the same size, but more bell-shaped cervically. D. narrower mesiodistally in comparison with their crown length in the anterior teeth.

Back 12

MORE BULBOUS AND CONSTRICTEDThe correct answer is choice B. In general, primary teeth differ from permanents in a number of ways. They are generally smaller than their permanent counterparts in all dimensions. The are usually "squatter" in appearance, with their crowns shorter, relative to their mesio-distal length. They tend to have bulbous cervical ridges, on the buccal of molars, and both buccal and lingual of anteriors. They are whiter in color, and the enamel is relatively thinner.

Front 13

As the mouth is opened widely, the articular disk moves in what direction in relation to the articular eminence? A. Laterally B. Anteriorly C. Posteriorly D. Medially E. Superiorly

Back 13

ANTERIORLYThe correct answer is choice B. Fibers from the lateral pterygoid muscle enter the capsule and disc of the temperomandibular joint. Opening of the mandible involves the lateral pterygoid pulling the neck of the condyle and joint capsule forward toward the articular eminence. In addition, the disc may move slightly downward along the articular slope (inferiorly), but this is not an answer choice here.

Front 14

As you go from maxillary first to second to third molar, the MOST significant progressive change throughout the three teeth is A. loss of rhomboid shape B. loss of Carabelli cusp on the third molar C. decrease in size of one of the four major cusps D. loss of oblique ridge on the third molar

Back 14

DECREASE IN SIZE OF ONE OF THE FOUR MAJOR CUSPSThe correct answer is choice C. The distolingual cusp of the maxillary molar becomes less and less prominent as you go from first to second to third molar. The shape of maxillary molars is usually rhomboid, but it may be lost primarily in the third (but not second) molar. The Carabelli cusp (trait) is a small to medium-sized projection from the mesiolingual cusp of the first (but not second) molar. All three molars generally have an oblique ridge connecting the mesiolingual and distobuccal cusps, although it is much reduced in the third (but not the second) molar. So the size of only the distolingual cusp progressively changes as you go from first to second to third.

Front 15

At 9 years of age how many primary teeth remain in the mouth? A. 0 B. 4 C. 8 D. 12 E. 18

Back 15

4The correct answer is choice D. By nine years of age,the child has usually lost mandibular central (6-7 years), mandibular lateral (7-8 years), maxillary central (7-8 years) and maxillary lateral (8-9 years) incisors. The mandibular canine (9-10 years), first primary molar (10- 1 1 years). second primary molar (1 1-12 years) maxilary canine (I 1-12 years), first primary molar (10-1 l years) and second primary molar (10- 12 years) still remain. This amounts to 6 upper and 6 lower teeth.

Front 16

Because of the presence of a fissured groove cavity preparations MOST frequently need to be extended from the occlusal surface to the A. facial surface of maxillary molars. B. lingual surface of maxillary molars. C. lingual surface of mandibular molars. D. lingual surface of mandibular first premolars.

Back 16

The correct answer is choice B. On the lingual surface of maxillary molars, the distolingual groove extends from the occlusal surface onto the lingual. This separates the distolingual and mesiolingual cusps. It is often deep, and when restored often cames the preparation onto the lingual surface. The facial groove generally does not extend deeply onto the facial surface so that it requires facial extension. The lingual groove of mandibular molars tends to stay on the occlusal surface, and not go deeply down onto the lingual. The lingual surface of mandibular first premolar often has a mesioloingual developmental groove. It is generally short and shallow and not commonly restored along with the occlusal surface.

Front 17

Calcification of six-year molars begins A. at 6 years B. 6 months prenatal C. at birth D. 6 months postnatal E. at approximately 3 years of age

Back 17

The correct answer is choice C. This question is commonly asked on NDB. It is the only tooth whose average beginning of calcification coincides with birth. It is also the first permanent tooth to begin calcifying. Calcification roughly, but not exactly, follows the order of eruption. Generally, teeth that begin to calcify first, erupt first, but there are many exceptions to this rule. An example of the rule, (and not the exception) is found in molars where the second molar begins calcifying at about 2-3 years and the third molar at 7-8 years. In both arches, canines calcify before first premolars, and first premolars calcify before second premolars.

Front 18

Contraction of the lateral pterygoid muscle produces 1. initial upward closure of the mandible. 2. forward movement of the condyle from the articular fossa. 3. posterior displacement of the condyle from the articular eminence. 4. final forceful closure of the molars through a bolus of food.

Back 18

The correct choice is 2. The lateral pterygoid muscle moves the condyle forward, downward and medially. It originates on the lateral pterygoid plate and inserts on the neck of the condyle and the articular disk. Choice #1: Initial closure of the mandible is accomplished by the masseter and medial pterygoid muscles. The masseter originates on the zypomatic arch and inserts on the outer surface of the angle of the mandible. The medial pterygoid muscle originates on the lateral pterygoid plate and inserts on the inner surface of the angle of the mandible. Choice #3: Posterior displacement of the condyle is accomplished mostly by the posterior part of the temporalis muscle. Choice #4: Final forceful tooth closure is mainly due to the anterior part of the temporalis muscle. The temporalis muscle originates on the temporal crest of the cranium and inserts on the coronary process and the anterior ramus of the mandible.

Front 19

During a working movement of the mandible, the facial cusp ridges of the maxillary first premolar on the working side oppose which of the following mandibular structures? A. The facial embrasure between the canine and the first premolar B. The distal cusp ridge of the first premolar and the mesial cusp ridge of the second premolar C. The distal cusp ridge of the second premolar and the mesial cusp ridge of the first molar D. The mesiofacial groove of the first molar.

Back 19

The correct answer is choice B. In a working movement (let's assume left working), the mandible will move left, and the left I maxillary first premolar facial cusp, which is a non-supporting cusp, will make contact with the mandibular facial surfaces as they move past. The mandibular teeth are positioned one half tooth mesial to the maxillary, so the maxillary first premolar should contact I both its counterpart, but also the tooth just distal to its counterpart. Therefore, both the first and second mandibular premolar facial surfaces will make contact.

Front 20

During nonmasticatory swallowing, teeth are usually 1. protruded. 2. in a working arrangement. 3. in contact in intercuspal position. 4. None of the above. This is a nonexistent act.

Back 20

The correct choice is 3. The teeth are in the intercuspatory position when swallowing occurs. In fact, telling a patient to swallow is often a good way to get a patient into maximum intercuspation. Choice #4: Non-masticatory swallowing occurs throughout the day and night, more frequently when awake. Otherwise, a large amount of saliva would build up.

Front 21

During the eruption of permanent teeth, which bone processes occur? A. Both resorption and deposition B. Neither resorption nor deposition C. Resorption only D. Deposition only

Back 21

The correct answer is choice A. This can be reasoned by noting that there must be bone resorption coronal to the emerging crown to have room for the crown to move into to approach the soft tissue (gingiva) above it. Bone deposition is also logical but less obvious. There must be bone deposition below the roots as the tooth moves coronally and bone deposition around the root to fully fill the shape of the alveolar socket surrounding the new root.

Front 22

Each of the following cusps of the maxillary molars is part of the maxillary molar primary cusp triangle EXCEPT one. Which one is this EXCEPTION? A. Mesiofacial B. Mesiolingual C. Distofacial D. Distolingual

Back 22

The correct answer is choice D. Maxillary molars have a generally rhomboidal shape, and three major cusps forming a distinct triangular pattern, the primary cusp triangle. Note that primary here refers to important, not primary. as in primary (deciduous) I teeth. The three major cusps are the mesiobuccal, mesiolingual and distobuccal. Not included are the distolingual, which is small, and on the first molar, the cusp of Carabelli, which is even smaller, when present.

Front 23

Each of the following is a function of the periodontal ligament EXCEPT 1. sensory. 2. nutritional. 3. supportive via the fibers. 4. formative via its cellular elements. 5. maintenance of the epithelial attachment

Back 23

The correct choice is 5. The periodontal ligament does not participate in the epithelial attachment to the tooth. This is maintained by the junctional epithelium of the gingival sulcus. The periodontal ligament carries nerves and blood vessels, which are the sensory and nutritive functions; it supports the tooth via the fibers; and has cementoblasts, osteoblasts and fibroblasts which make up the formative function. It has a fifth protective function to cushion the tooth against force. To summarize the five functions of the periodontal ligament: 1 ) sensory, 2) nutritive, 3) supportive, 4) formative, and 5) protective.

Front 24

Each of the following morphologic structures can be seen on any incisor EXCEPT one. Which one is this EXCEPTION? A. Cingulum B. Mesial marginal ridge C. Lingual fossa D. Transverse ridge

Back 24

The correct answer is choice D. Incisors generally contain both mesial and distal marginal ridges, and a depression between them, the lingual fossa. Incisors, as well as canines contain a cingulum, or pronounced lingual bump near the cervical end of the crown. A transverse ridge is not present. This can be found on the mandibular fint premolar. It is a ridge seen on the linguallocclusal surface of the crown, connecting the buccal and lingual cusps.

Front 25

Exfoliation of primary canines is most likely to occur during the age range A. 6-7 B. 8-9 C. 10-11 D. 12-13

Back 25

The correct answer is choice C. The canines erupt, as with most other teeth, in the order mandibular, then maxillary. The eruption of the maxillary is more predictable, with most occurring between 11 and 12. The mandibular may erupt as early as 9, but normally at 10-11. Eruption times, of course, are averages and are variable. So 10-11 is our closest answer. It is extremely rare to see a permanent canine at 8, so rule out choice B. Likewise, the mandibular canine is almost always erupted before 12, so rule out choice D.

Front 26

From a proximal view, which of the following describes the crown outline on a mandibular posterior tooth? A. It is designed to protect against root fracture by having the crown structure serve as root support. B. It is designed to allow for a minimum amount of chewing efficiency on the coronal surface of the tooth. C. It is usually rhomboidal and has a design flaw that encourages cusp fracture. D. It is usually trapezoidal and has a design flaw that encourages cusp fracture.

Back 26

The correct answer is choice 1. A maxillary canine has an almost vertical inclination when viewed proximally. Maxillary lateral incisors, choice 2, lean slightly more buccally when viewed from the proximal and maxillary centrals slightly more. In actual degrees, the canines are 16 degrees off of vertical while the maxillary laterals and centrals are 26 and 28, respectively. Do not spend time remembering the numbers. The most vertical maxillary teeth are the first and second premolars, 5 and 6 degrees from vertical respectively. Mandibular centrals and laterals are 22 and 23 degrees off from vertical, respectively. The mandibular canine is more vertical than the mandibular incisors and as in the maxillary arch, the premolars are most vertical. In general, the order would be premolar, canine, incisor in order of decreasing vertical position. So the correct answer to question is choice 1.

Front 27

From the facial view, the maxillary first molar has its lingual root apex in line with which of the following? A. Facial groove B. Distofacial line angle C. Distofacial cusp tip D. Mesiofacial cusp tip E. Mesiodistal diameter midpoint

Back 27

The correct answer is choice A. The palatal root of the maxillary first molar tends to diverge outwards in a palatal direction, but be approximately centered in the mesio-distal direction. Looking at it from the facial should place it behind the facial (buccal) groove. This groove separates the mesiobuccal and distobuccal cusps. Since the mesiobuccal cusp is larger, this groove is slightly distal to the mesio-distal midpoint.

Front 28

From the incisal aspect, the crown of a maxillary canine normally exhibits which of the following? A. A trapezoidal outline B. Symmetry between its mesial and distal portions C. A mesial portion that is thinner faciolingually than the distal portion D. A distal portion that displays some concavity in its facial outline E. Less faciolingual thickness than the crown of a mandibular canine

Back 28

The correct answer is choice D. From the incisal, the crown of the maxillary canine is somewhat rhomboidal or diamond shaped. Its mesial portion is wider bucco-lingually than its distal portion, and is more bulbous and convex as well. The distal portion is narrower and concave on the labial surface, showing a depression there. In all dimensions, the maxillary canine is larger than its mandibular counterpart.

Front 29

How many cingula exist in each arch? A. 2 B. 4 C. 6 D. 8 E. 12

Back 29

The correct answer is choice C. Cingula is the plural for cingulum, a rounded protuberance or elevation located on the lingual surfaces of anterior teeth. Therefore, central incisors, lateral incisors, and canines all have recognizable cingula. The cingulum, may be thought of as an undeveloped lingual cusp. When we view premolars in both arches, they no longer are said to have cingula, but instead have pronounced lingual cusps. In this case, each arch has two central incisors, two lateral incisors and two canines, for a total of six teeth.

Front 30

How soon after eruption of a permanent tooth is the apex usually fully developed? 1. Immediately 2. 3 months 3. 2 or 3 years 4. 5 or 6 years

Back 30

The correct answer is #3. The apex of a permanent tooth is approximately one-half formed at the time of the eruption and the root is generally completed 2 to 3 years after eruption. This fact is important when treatment planning endodontic procedures in young people.

Front 31

If a permanent maxillary first molar has a fourth root canal, it will usually be found in A. Its own fourth root B. The mesiobuccal root C. The mesiolingual root D. The palatal (lingual) root E. It cannot be found: a maxillary first molar always has three root canals

Back 31

The correct answer is choice B. The most common arrangement of root canals in the maxillary first molar is three, one in each root (mesiobuccal, distobuccal, palatal). A 4 canaled version is fairly common. The orifice to the canal is located in the area between the orifice to the mesiobuccal and palatal canals. The canal itself is located in the mesiobucccal root. It is estimated that 30-40% of maxillary first molars have this orifice, whether or not two canals end in one foramen or two. Endodontists often assume it to be there until proven otherwise.

Front 32

In a cervical cross section, which premolar(s) sometimes exhibit a root outline and a pulp chamber floor outline that are both kidneyshaped? A. Maxillary first B. Mandibular first C. Maxillary second D. Mandibular second E. All premolars

Back 32

The correct answer is choice A. The maxillary first premolar may have a kidney shaped root outline and pulp outline because of the tendency of the tooth to have a deep mesial root concavity, which will indent that side. The other premolars listed will have cross sectional root shapes at the CEJ varying from oval to indented on both sides, giving a figure-8 appearance.

Front 33

In a Class II occlusal relationship, the tip of the facial cusp of a mandibular first premolar lies directly below the contacting area between which maxillary teeth? A. Canine and lateral incisor B. Canine and first premolar C. First and second premolars D. Second premolar and first molar

Back 33

The correct answer is choice C. Lets look at a normal Class I relationship first. The facial cusp of the mandibular first premolar is a holding cusp that contacts the mesial marginal ridge of the maxillary first premolar and comes close to contacting the distal of the maxillary canine. In a Class II relationship, move the mandible backwards (distally), and the mandibular first premolar will now be between the first and second maxillary premolars.

Front 34

In a permanent mandibular first molar, what developmental groove separates the distofacial cusp from the distal cusp? A. Facial B. Buccal C. Distofacial D. Mesiofacial E. Oblique

Back 34

The correct answer is choice C. The occlusal surface of the mandibular first molar consists of five cusps: MB, DB, ML, DL, and distal. There are three major pits: mesial, central, and distal. A central groove connects the mesial and central pits and also separates the MB and ML cusps. A mesiobuccal groove separates the MB from the DB cusp. A distobuccal (distofacial) groove separates the DB cusp from the distal cusp. A lingual groove separates the ML and DL cusps.

Front 35

In an acquired Class 3, crossbite relationship, as the mandible retrudes, the maxillary lateral incisor contacts which of the following teeth? A. Central incisor B. Lateral incisor C. Central and lateral incisors D. Canine and lateral incisors

Back 35

The correct answer is choice D. In a Class III crossbite, the mandibular teeth are protruded beyond the maxillary counterparts. If these mandibular teeth are drawn in (retruded), then their lingual surfaces will contact the facial surfaces of the maxillary teeth. Since the mandibular teeth are narrower, the mandibular central contacts only the wider maxillary central. The mandibular lateral will contact both the distal part of the maxillary central and the mesial part of the maxillary lateral. The mandibular canine will contact the distal part of the maxillary lateral, and the mesial part of the maxillary canine.

Front 36

In an eight-year-old patient, which teeth are expected to be present? A. Permanent central and lateral incisors, premolars, and first molars, with primary canines B. Permanent central and lateral incisors, and first molars, with primary canines and molars C. Permanent central and lateral incisors, canines, and first molars, with primary molars D. All permanent teeth, except second and third molars

Back 36

The correct answer is choice B. By age six, permanent first molars are usually present. By age seven, the mandibular incisors and the maxillary centrals are usually in. Maxillary laterals often erupt around ages seven to eight. Since canines usually erupt between 9 and 11 years, we still expect primary canines in our eight-year-old. Similarly, for premolars, the range may be from 9 years up to about 12 years, so primary molars, not premolars, should be present in our eightyear- old. Note that, as previously stated, the question must choose a pretty definitive age, such as eight. Choosing age 10 would lead to far too much variation and unpredictability, especially concerning canines and premolars.

Front 37

In an ideal intercuspal position, the distofacial cusp of a maxillary first molar opposes which feature on a mandibular first molar? A. The distal cusp B. The distofacial cusp C. The distofacial developmental groove D. The rnesiofaciai developmental groove

Back 37

The correct answer is choice C. The facial cusps of maxillary molars are guiding cusps and oppose grooves on the facial surface of mandibular teeth. Since the mandible is about one half tooth forward of the maxilla, we look for a groove one half tooth distal to the distofacial area of the maxillary molar. This is the groove between the distobuccal and distal cusp of the mandibular molar.

Front 38

In an ideal intercuspal relation in a normal dentition, each of the following teeth contacts each other EXCEPT one. Which one is this EXCEPTION? A. Maxillary first premolar and mandibular second premolar B. Maxillary first molar and mandibular second premolar C. Maxillary second premolar and mandibular first molar D. Maxillary second molar and mandibular third molar

Back 38

The correct answer is choice B. Maxillary posterior teeth generally contact their own counterpart in the mandibular arch, and the tooth just distal to it. Maxillary first premolars contact mandibular first and second premolars. Maxillary first molars contact mandibular first and second molars. Maxillary second premolars contact mandibular second premolars and first molars. Maxillary second molars contact mandibular second molars and third molars.

Front 39

In an ideal intercuspal relation, the mesiofacial cusps of the mandibular second molars contact the maxillary molars in (on) the A. distal fossae of the second. B. central fossae of the second. C. lingual embrasures between the first and second. D. facial embrasures between the first and second. E. mesial marginal ridges of the second.

Back 39

The answer is choice E. Facial cusps of mandibular teeth are supporting cusps and occlude on marginal ridges of the maxillary teeth except for the distobuccal cusp of the molars which occludes with the central fossa of the maxillary molars and the distal cusp of the mandibular first molar which occludes with the distal triangular fossa of the first maxilary molar. So the mesiofacial cusp of the mandibular second molar should contact the distal marginal ridge of the maxillary first molar and mesial marginal ridge of the maxillary second molar.

Front 40

In an ideal intercuspal relation, the mesiolingual cusp of the maxillary first molar contacts the mandibular first molar in (on) the A. central fossa. B. distal fossa. C. mesial fossa. D. mesial marginal ridge. E. distal marginal ridge.

Back 40

The correct answer is choice A. This reminds us of our general rule: maxillary posterior cusps make contact on mandibular marginal ridges EXCEPT for the mesiolingual cusps of the maxillary first and second molars which occlude in the central fossae of the corresponding mandibular teeth.

Front 41

In an ideal intercuspal relation, the oblique ridge of the maxillary first molar opposes which structure of the mandibular molar? A. The interproximal area between first and second B. The developmental groove between the mesiofacial and distofacial cusps of the first C. The developmental groove between the mesiolingual and distolingual cusps of the first D. The developmental groove between the distofacial and distal cusps of the first

Back 41

The correct answer is choice D. The distolingual cusp of the maxillary first molar occludes with the mesial marginal ridge of the second molar and the distal marginal ridge of the first molar. Therefore, the oblique ridge, which is slightly mesial to the distolingual cusp of the maxillary first, should occlude with something slightly mesial to the area just mentioned. This would be the area between the distal cusp and distobuccal cusp of the first molar. This is the distobuccal groove area.

Front 42

In an ideal occlusion, maxillary posterior tooth buccal cusps oppose A. marginal ridges only B. marginal ridges and fossae C. grooves and embrasures D. grooves and marginal ridges

Back 42

The correct answer is choice C. Maxillary LINGUAL cusps and mandibular buccal cusps are holding (support) cusps, whereas maxillary BUCCAL cusps and mandibular lingual cusps are guiding cusps. Therefore, the maxillary buccal cusps lie slightly buccal to the mandibular buccal cusps and will fit into grooves and embrasures, such as the buccal grooves of mandibular molars. These guiding cusps have a function only during horizontal mandibular movements.

Front 43

In carving an occlusal amalgam restoration in a permanent mandibular second molar, which of the following shapes is the most typical groove pattern? 1. H 2. L 3. U 4. Y 5. +

Back 43

The correct choice is #5, a plus or cross shape. The permanent mandibular second molar generally has four cusps with a cross groove pattern. Choices #1 and 3: H and U shapes are not common groove patterns, although the mandibular second premolar may exhibit these patterns as variations. Choice #2: An L-shaped groove pattern is typical of the mesial occlusal grooves of the maxillary molars. Choice #4: A Y-shaped groove pattern is characteristic of the mandibular second premolar.

Front 44

In cervical cross-section, the root of a mandibular canine is described as A. triangular. B. roughly conical. C. flattened in a mesiodistal direction. D. broader mesiodistally on the lingual than on the facial.

Back 44

The correct answer is choice C. In cross section mandibular canine roots are roughly oval. They are longer bucco-lingually. and narrower mesio-distally. They are slightly wider towards the buccal. The pulp canal tends to be ovalish as well. Maxillary canine root sections tend to be more similar, and slightly more elongated in the bucco-lingual direction.

Front 45

In contrast to maxillary canine crowns, mandibular canine crowns have which of the following anatomically? A. Greater measurements, mesiodistally B. Greater measurements, faciolingually C. More accentuated marginal ridges D. Well-defined lingual pits E. Less-pronounced cingula

Back 45

The correct answer is choice E. In general, when comparing maxillary and mandibular canines you will find that the mandibular canines are smaller (mesio-distally AND bucco-lingually), they lack lingual pits, (maxillary canines have them as rare variants) have smaller cingula, and less pronounced marginal ridges. Mandibular canines are more symmetrical when viewed from the occlusal.

Front 46

In extraction of premolars, the dentist may sometimes use a rotation or circular motion. Which premolar should NEVER be extracted with this type of motion? A. Maxillary first B. Maxillary second C. Mandibular first D. Mandibular second

Back 46

The correct answer is choice A. The choice of direction of movement used by the dentist in extracting a tooth depends greatly on the likely root form of the tooth involved. Teeth with circular or conical shaped roots can easily be rotated during extraction. To a lesser extent, a slightly oval shaped root could also be rotated during extraction. Multi-rooted teeth and teeth with extremely broad, flat, fused roots cannot be rotated without fracture of the root or crown. While there is much variation in root form among the premolars, the maxillary first premolar almost invariably has two roots, a buccal and lingual, and whether fused or not, will not rotate without breaking. Maxillary seconds can have two roots but usually do not and the one root can be conical. Similarly, both mandibular premolars are usually single rooted and potentially can be rotated out. Of the two, the mandibular first premolar is more likely to have a second root.

Front 47

In normal occlusion, and in a left working movement, the mesiofacial cusp of the maxillary left second molar passes through which of the following mandibular structures? A. The embrasure between the left first and second premolars B. The embrasure between the left first and second molars C. The facial groove of the left first molar D. The facial groove of the left second molar E. The distofacial groove of the left first molar

Back 47

The correct answer is choice D. The mesiofacial cusp of the maxillary second molar is a guiding cusp. It will pass through an area on the facial surface of a mandibular tooth. Since the mandible is about one half tooth forward relative to the maxilla, look for a surface on the mandibular second molar facial area, slightly distal to the area of the mesiobuccal cusp. This is the facial groove of the second molar.

Front 48

In protrusive movement, the mandibular canines in a Class II occlusal relationship articulate with which of the following maxillary teeth? A. Canines only B. Lateral incisors only C. Canines and lateral incisors D. Canines and first premolars

Back 48

The correct answer is choice C. Remember that the mandibular teeth are located about one half tooth mesial to the corresponding maxillary teeth. So although they are not normally in contact in centric occlusion, the mandibular canine is located in the area of the mesial half of the mandibular canine and the distal half of the lateral incisor. When the mandible protrudes, the teeth will contact in that position.

Front 49

In relation to maxillary canines, maxillary first premolars usually erupt: A. before canines B. after canines C. at nearly the same time as canines

Back 49

The correct answer is choice A. Although there is some variation in eruption times, the most usual order of eruption in the maxillary arch is first premolar, second premolar, canine. In the mandibular arch it is most often canine, first premolar, second premolar. The mandibular version generally erupts before the maxillary. Two year ranges for the teeth in question are: maxillary first premolar (10-11), maxillary second premolar (10-11), maxillary canine (11 -12), mandibular first premolar (10-11), mandibular second premolar (11-12), mandibular canine (9-10). The maxillary arch is generally more predictable than the mandibular.

Front 50

In the comparison of the rhomboidal and heart-shaped crown outlines of maxillary molars, the crown portion that differs MOST in contour and size is the A. mesiofacial. B. distofacial. C. mesiolingual. D. distolingual.

Back 50

The correct answer is choice D. Most maxillary molars have a rhomboidal occlusal crown outline due to the presence of four cusps. As one of the cusps, the distolingual, becomes less prominent, or absent, the occlusal outline changes and becomes more heart shaped. The smaller distolingual cusp is sometimes a variety of tooth form, and is more common as you go from first to second to third molar. The third molar most commonly has this heart shaped form.

Front 51

In the diagram of Posselt's envelope of motion, maximum intercuspal position is the 1. lowest point. 2. most anterior point. 3. most posterior point. 4. most superior point.

Back 51

The correct choice is #4. On the diagram of [Posselt's] envelope of motion, the intercuspal position is the most superior point labelled #3 on the diagram. Choice #1: The lowest point is #8 which is the position of maximum opening. Choice #2: The most anterior point is #1, the maximum protruded position. Choice #3: The most posterior point is #4, the retruded contact position.

Front 52

In which of the following molars is the mesial fossa most distinctly separated from the remainder of the occlusal table by a transverse ridge? 1. Maxillary first 2. Mandibular first 3. Maxillary second 4. Mandibular second

Back 52

The correct choice is 2. The triangular ridges of the mesiobuccal and mesiolingual cusps of the mandibular first molar join to form a transverse ridge which separates the mesial fossa from the rest of the occlusal table. This transverse ridge is not quite as prominent in the mandibular second molar which is choice #4. Choices #1 and 3: In the maxillary molars, the central fossa is separated from the distal fossa by the oblique ridge running from mesiolingual to distobuccal cusps.

Front 53

In which of the following teeth is the mesial portion MOST distinctly separated from the remainder of the occlusal table by a transverse ridge? A. Primary maxillary first molar B. Primary mandibular first molar C. Primary mandibular second molar D. Mandibular second premolar E. Mandibular first molar

Back 53

The correct answer is choice B. Transverse ridges are most noticeable in two teeth, the permanent mandibular first premolar, and the primary first mandibular molar. A transverse ridge connects buccal and lingual sections of a tooth and separates mesial and distal. In the primary mandibular first molar, the transverse ridge connects the large mesiobuccal and mesiolingual cusps. This structure is more common and more noticeable on the primary first molar than on the permanent first premolar. The other teeth listed do not have transverse ridges.

Front 54

Mandibular lateral translation (Bennett movement) occurs during the A. earliest stage of lateral movement. B. latter stage of protrusive movement. C. middle stage of retrusive movement. D. hinge axis movement of the mandible. E. ending stage of exhibiting a border movement.

Back 54

The correct answer is choice A. The Bennett movement involves whole body movement of the mandible in a lateral direction. Lets use process of elimination for our answers. In lateral movement, both rotation and translation occur. Translation occurs particularly on the working side of the TMJ, in combination with some rotation, primarily rotation around a vertical axis. The translation component is known as the Bennett shift, and is a whole body shift of the working side of the mandible of about 1 mm laterally. Protrusive movement is primarily translation caused by the lateral pterygoid muscle, but forward and not lateral. Similarly. retrusive movement is translation backwards, not laterally, and is caused primarily by the temporalis muscle. Hinge axis movement of I the mandible refers to opening. The beginning of opening is rotational around a horizontal axis through the TMJ. Later siages of opening involve translation, to the maximal opening possible.

Front 55

Maxillary tooth crowns exhibit concavities on which of the following surfaces? A. The mesial of central incisor and first premolar B. The mesial of canine and first molar C. The distal of first premolar and the mesial surface of second molar D. The mesial of first premolar and the distal of first molar E. The distal of the first molar and the mesial of the second molar

Back 55

The correct answer is choice D. The most well known mesial concavity on both crown and root is on the mesial of the maxillary first premolar. So we are most likely going to choose between choices A and D. The central incisor does not have a mesial crown concavity, although a root groove may be present. Likewise, the canine often has proximal root concavities that do not extend to the crown. Second premolars and distals of first premolars also may have this trait, but again, it does not extend to the crown. The cervical third of the mesial surface of the first molar sometimes exhibits a concavity not found normally on the second molar, or on the distal of the first, which is usually quite convex.

Front 56

Mesial inclination of lingual cusps is present in which maxillary premolars? 1. First premolars only 2. Second premolars only 3. Both first and second premolars 4. Neither first nor second premolars

Back 56

The correct answer is choice 3. Mesial inclination of lingual cusps is present on both maxillary premolars. This means that when viewed from the lingual, the lingual cusp tends to lean towards the mesial and most of the lingual cusp is mesial to the midline. t It is a characteristic of the maxillary premolars and not consistently found in either the mandibular first or second premolar. In the mandibular first premolar, the lingual cusp may be midline or mesial or distal to the midline. In the mandibular second premolar, often gd two lingual cusps are present. So the correct answer to question is choice 3.

Front 57

Mesiolingual grooves can be found on which of the following permanent teeth? A. Maxillary canines B. Mandibular first premolars C. Maxillary first molars D. Mandibular second molars

Back 57

The correct answer is choice B. Mandibular first premolars often have a mesiolingual developmental groove which begins on the occlusal and extends down the mesiolingual surface. Maxillary first molars have distolingual grooves but not mesiolingual. Mandibular molars have lingual grooves.

Front 58

Moving the mandible from a maximum intercuspal position to a retruded contact position usually results in 1. increased occlusal vertical dimension. 2. increased horizontal overlap. 3. decreased vertical overlap. 4. all of these.

Back 58

posterior to centric occlusion or maximum intercuspation. It also represents a position where the condylar head is located closer to the distal section of the glenoid fossa. Because retruded contact implies that the teeth are not in complete occlusion which is the greatest intercuspation and smallest vertical dimension, they are therefore slightly farther apart with a greater vertical dimension. If the mandible moves posteriorly, there will be greater distance from the mandibular anteriors to the maxillary anteriors or slightly increased horizontal overlap. If the teeth are slightly more separated vertically, there will be less vertical overhang of the maxillary anteriors over the mandibular. So all three choices, 1.2 and 3 are all correct and the correct answer to question is choice 4.

Front 59

On a maxillary molar, which of the following ridges is formed by the union of the distal cusp ridge of the mesiolingual cusp and the triangular ridge of the distofacial cusp? A. Cuspal B. Central C. Marginal D. Oblique E. Transverse

Back 59

The correct answer is choice D. The oblique ridge is found on maxillary molars. It connects the distobuccal and mesiolingual cusps. It also separates the distolingual cusp from the main cusp triangle of the molar. Just distal to it is the distolingual groove.

Front 60

On the crowns of maxillary canines, which lobe includes the cusp tip? A. Mesiolingual B. Distofacial C. Mesiofacial D. Lingual E. Middle facial

Back 60

The correct answer is choice E. The maxillary canine is often described as having three facial lobes, mesial, distal and middlc The cusp tip is located almost centrally. on the middle lobe, slightly to the mesial of center. The lingual lobe contains the cingulum.

Front 61

On the occlusal surface of a maxillary first molar, the total number of pits is normally the same as found on the occlusal surface of which premolar? A. Maxillary first B. Mandibular first C. Maxillary second D. U-type mandibular second E. Y-type mandibular second

Back 61

The correct answer is choice E. The maxillary first molar has three pits, the mesial, distal and central. The maxillary first premolar generally has two, a mesial and a distal, as does the maxillary second. The mandibular first generally has the same two. The U type mandibular second premolar is the two cusped type, with the same two pits. However, the Y type is the three cusped type, which contains a central pit in addition to the mesial and distal.

Front 62

Perikymata are the result of 1. enamel hyperplasia. 2. enamel hypoplasia. 3. interstitial growth. 4. normal enamel apposition. 5. early ameloblastic degeneration.

Back 62

The correct answer is choice 4. Perikymata are normal enamel features. Line of Retzius which form early in enamel formation complete an arc of enamel and return to the dentinal enamel junction. Later lines of Retzius do not complete an arc-like pattern and terminate on the enamel surface. They form a series of grooves and elevations at the enamel surface. The grooves are known as imbrication lines and the elevations are known as perikymata. So the correct answer to question is choice 4.

Front 63

Primary molars differ from permanent molars in that primary molars 1. have heavier root trunks. 2. tend to have less pronounced cervical ridges. 3. have thicker enamel compared to the total bulk of crowns. 4. have flatter facial and lingual surfaces extending from the occlusal to the cervical ridge.

Back 63

The correct answer is choice 4. Let's review them one by one. Primary molars generally have lighter, thinner root trunks. The roots are smaller due to the smaller size of the tooth and the widespread position of the roots to surround the developing crown of the succedaneous tooth. So choice 1 is incorrect. Choice 2 is also incorrect. A number of primary molars have pronounced cervical ridges, including the primary maxillary first molar and primary mandibular first molar. Choice 3 is incorrect. Primary teeth are generally characterized by thinner enamel. Choice 4 is our correct answer. The facial and lingual outline of the primary molars are usually straight from the occlusal surface to cervical ridge and then bulbous at the cervical ridge. The permanent molars facial and lingual surfaces tend to be more completely and regularly convex without a straight surface. So the correct answer to question is choice 4.

Front 64

Prominent cervical ridges or bulges are noted on which surfaces of primary teeth? A. Linguals of molars and buccals of incisors B. Buccals and linguals of molars and buccals of incisors C. Linguals of incisors and buccals of molars D. Buccals and linguals of incisors and buccals of molars E. Buccals of molars and buccals of incisors

Back 64

The correct answer is choice D. Prominent cervical ridges are characteristic of certain primary teeth. There is a constriction of the tooth at the cervical line, giving a bulge or ridge effect immediately incisal to the CEJ. These cervical ridges are found on the buccal and lingual of primary anteriors, and the buccal only of molars. In molars, the cervical ridge makes the occlusal table look constricted as the tooth is viewed from the occlusal.

Front 65

Protrusive movement is produced primarily because of contracture of which of the following muscles? A. Masseter B. Mylohyoid C. Temporalis D. Medial pterygoid E. Lateral pterygoid

Back 65

The correct answer is choice E. The masseter and medial pterygoid act primarily to close (elevate) the mandible. They form the "masseteric sling". The temporalis can both elevate and retract the mandible, depending on which fibers are contracted. The mylohyoid can play a very small role as an accessory in opening (depressing) the mandible. The lateral pterygoid is the primary protruder and opener (depresser) of the mandible.

Front 66

The anterior tooth LEAST likely to have a mesial or distal root concavity is the: A. Maxillary central incisor B. Maxillary canine C. Mandibular canine D. Mandibular central incisor E. Mandibular lateral incisor

Back 66

The correct answer is choice A. Root concavities are grooves running vertically along the proximal side of a root. They may be shallow or deep, and if deep, may make the teeth appear double rooted. All of the mandibular anteriors can have this groove. It can be especially deep in mandibular canines, approaching a double-rooted appearance. It is also common in maxillary canines, although rarely as deep. It is almost never found on maxillary central incisors, whose root form is usually roundish, triangular and convex.

Front 67

The apices of a mandibular second molar are located A. posteriorly to the pterygomandibular raphe. B. inferiorly to the mylohyoid muscle insertion. C. inferiorly to the masseter muscle insertion. D. inferiorly to the medial pterygoid muscle insertion.

Back 67

The correct answer is choice B. The pterygomandibular raphe joins the buccinator and superior constrictor muscles. It is anterior and superior to the second mandibular molars. The mylohyoid line is the attachment of the mylohyoid on the medial side of the mandible. It moves in an upward slanting direction, getting higher on the mandible as you move more posterior. By the second 1 and third molar area, it is superior to the molar root apices. Both the masseter and medial pterygoid insert on the angle and ramus, below the second molar root apices.

Front 68

The Bennett movement is best described as the 1. medial shift of the working condyle. 2. lateral movement of the non-working condyle. 3. bodily shift of the mandible in the direction of the working condyle. 4. bodily shift of the mandible in the direction of the non-working condyle.

Back 68

The correct answer is choice 3. Let's review the terminology of lateral or working movements. The side to which the mandible moves is known as the working side and the condyle of that side is the working condyle. The opposite side is known as the nonworking or balancing side. The working condyle exhibits a small sliding lateral movement during lateral excursions and this is known as the Bennett movement. So the correct answer to question is choice 3.

Front 69

The cemental union of two fully formed teeth that were originally separate entities is 1. fusion. 2. concrescence. 3. dilaceration. 4. dens in dente. 5. hypercementosis.

Back 69

The correct answer is choice 2. Let's define the five terms. Choice 1, fusion, is incorrect. Fusion is the result of two adjacent teeth joined by a union of dentin. The result is a large crown or double crown with two distinct root canals. Choice 2 is correct. Concrescence is the joining of roots of two teeth by cementum. This usually occurs after the teeth are formed and have most implications in terms of the difficulty of extraction. Choice 3 is incorrect. Dilaceration of a root refers to a sharp angular deviation of the root from its normal long axis. Choice 4 is incorrect. Dens in dente refers to an inpocketing of the enamel organ into the pulp during tooth formation resulting in an enamel lined pit. This is most commonly found in the maxillary lateral incisor. Choice 5 is incorrect. Hyprcementosis refers to excess cementum development near the apex of the root but not involving union of the teeth. So the correct answer to question is choice 2.

Front 70

The concept of using a lateral checkbite record to set a respective condylar inclination implies which of the following? A. That the non-working side condyle has traveled against the posterior wall of the fossa B. That the working side condyle has traveled down the slope of the articular eminence C. That the non-working side condyle has moved anteriorly and medially D. That the working side condyle has moved toward the medial wall of the glenoid fossa

Back 70

The correct answer is choice C. At this stage (pre-prosthodontics), we can ignore the discussion of the lateral checkbite and just look to see which of our answer choices are true. In a working (lateral) movement, the mandible moves toward the working side. The condyle rotates and translates on the working side, and moves slightly laterally (Eliminate choice D). The condyle will only travel down the slope of the articular eminence during the translation phase of opening (depression). (Eliminate choice B). During a working movement, the non-working condyle moves forward and medially, not posteriorly (Eliminate choice A).

Front 71

The contraction of the lateral pterygoid muscle causes 1. the initial upward closure of the mandible. 2. forward movement of the condyle from the articular fossa. 3. posterior displacement of the condyle from the articular eminence. 4. the final forceful closure of the molars through a bolus of food.

Back 71

The correct answer is choice 2. Let's review the functions of the lateral pterygoid. This muscle extends from the pterygoid plate to the neck and condyle of the mandible and also contributes fibers to the articular disk. Its function is to depress or open the mandible, to move the mandible sideways in working movements, and to protrude the mandible or cause the mandible to move forward. When this occurs, the condyle moves anteriorly from its place in the articular or glenoid fossa. So choice 2 is correct. Choices 1 and 4 are incorrect because they deal with closure or elevation of the mandible. The lateral pterygoid does not elevate. The chief elevator muscles are the masseter, medial pterygoid and to some extent the temporalis. Choice 3 is incorrect because it involves backward posterior movement or retrusion. The lateral pterygoid is involved in protrusion while the chief retruder muscle is the temporalis. So the correct answer to question is choice 2.

Front 72

The dentist instructs the patient, who has a severed left lateral pterygoid muscle, to open wide. The patient's mandible will move in which direction? A. To the left B. To the right C. In a straight protrusive direction D. In a retrusive direction

Back 72

The correct answer is choice A. As a rule, the mandible will move TOWARD the injured side. Imagine both lateral pterygoids ; contracting and attempting to pull both condyles forward. However, only the right side can move. The right side of the mandible will move forward and medially as the left condyle stays in the same position. The mandible essentially rotates left instead of protruding or opening.

Front 73

The facial masticatory mucosa (attached gingiva) is narrowest on which mandibular tooth? 1. First molar 2. Second molar 3. First premolar 4. Central incisor

Back 73

The correct choice is 3. The narrowest zones of attached gingiva are located at the mandibular and maxillary first premolars. Choice #4: The widest zones of attached gingiva are found in the maxillary and mandibular incisor regions. Of course, these facts are only true in a normally aligned, periodontally healthy dentition.

Front 74

The glenoid fossa is an oval cavity or a depression in the 1. maxilla, just anterior to the malar process. 2. temporal bone, just anterior to the auditory canal. 3. mandible, just posterior to the internal oblique ridge.

Back 74

The correct choice is 2. The glenoid or articular fossa is located in the temporal bone just anterior to the auditory canal. It is the depression into which the mandibular condyle fits to form the temporomandibular joint.

Front 75

The healthy free gingiva aids in the selfcleansing process by 1. directing food particles toward the occlusal surface. 2. forcing particles away from the proximal space. 3. deflecting particles away from the free gingiva onto the interdental papillae. 4. adhering closely to the tooth surface below the height of contour of the cervical enamel.

Back 75

The correct answer is choice 4. The free gingiva when healthy and not inflamed forms a snug fitting soft tissue collar around the tooth. It prevents food and debris from entering the sulcus. It cannot direct food to the occlusal surface, choice 1. This is done partially by the cheeks and tongue. Choices 2 and 3 are also incorrect. Gingiva cannot force food particles in any direction as it is not a movable tissue. So it does not force food either into the interproximal area or away from it. Note also that forcing food interproximally would not aid the self cleansing process but instead would make self cleansing more difficult. So the correct answer to question is choice 4.

Front 76

The largest incisal/occlusal embrasure is located between which of the following teeth? A. Maxillary central and lateral incisors B. Mandibular central and lateral incisors C. Maxillary lateral incisor and canine D. Mandibular lateral incisor and canine E. Maxillary canine and first premolar

Back 76

The correct answer is choice C. Small incisal embrasures are noted between incisors (choice A and B) due to the high contact areas and right angle-type line angles at the mesio-incisal and disto-incisal. The low contact between the lateral incisor (middle third) and canine (junction of incisal and middle third) makes for a large incisal embrasure there. We do not find a large embrasure on the mandibular counterparts because of the higher contact area of the incisor and canine in that arch (incisal third on both teeth). Likewise, the contact of the maxillary first premolar (on the mesial) is high (incisal third).

Front 77

The lingual cusp(s) on which of the following mandibular posterior teeth is (are) approximately 2/3 the height of the respective facial cusp(s)? A. First premolar B. Second premolar C. First molar D. Second molar E. Third molar

Back 77

The correct answer is choice A. The mandibular tooth which has the most noticeable size difference between its buccal and lingual cusps is the mandibular first premolar. The tooth is very canine-like in form and unlike the three other premolars which have buccal and lingual cusps of similar size.

Front 78

The lingual cusps of a mandibular first molar must be restored to accommodate 1. centric relation. 2. working movement. 3. non-working movement. 4. protrusive position. 5. maximum intercuspation.

Back 78

The correct answer is choice 2. Lingual cusps of mandibular molars are nonsupport cusps. The supporting cusps, the buccal cusps of mandibular teeth and lingual cusps of maxillary teeth are involved in both centric occlusion or maximum intercuspation. choice 5. and centric relation or retruded contact. choice 1 . Nonsupport cusps, such as mandibular linguals, are not involved. They will be involved in working movements. choice 2. For example, in a left working movement, the mandible shifts left and the lingual cusps of the left mandibular teeth will be involved in chewing. On the nonworking side, the right side in this case, the lingual cusp moves left away from contact and are not involved. So choice 3 is incorrect. Choice 4 is incorrect. In protrusive movements anterior teeth contact while posterior teeth separate. Lingual cusps of mandibular teeth are not involved. So the correct answer to question is choice 2 .

Front 79

The most external layer of alveolar bone is the: A. Spongy bone B. Spicule bone C. Cortical bone D. Woven bone E. Cribriform plate

Back 79

The correct answer is choice C. Cortical bone refers to the outer layer of compact bone (usually with Haversian systems). Inner bone is usually spongy, with spicules of bone surrounded by marrow, and the spongy bone is not organized into Haversian systems. The term bundle bone refers to cortical bone with embedded collagen fibers, as in the periodontal ligament. Woven bone refers to early stages of bone formation by the intramembranous method. Remember that bone is formed intramembranously on a primitive connective tissue model, or through bony replacement of a cartilagenous model.

Front 80

The most symmetrical primary tooth, when viewed from the labial or lingual, is the: A. Maxillary central B. Maxillary lateral C. Mandibular central D. Mandibular lateral

Back 80

The correct answer is choice C. The most symmetrical primary tooth, when viewed from the labial or lingual is the mandibular central incisor. The incisal edge is straight and horizontal. The mesio-incisal and disto-incisal angles are close to 90 degrees. In the mandibular lateral, the body of the crown is slightly rotated, and the incisal edge tilts downward distally. The maxillary central incisor has a decidedly rounded disto-incisal angle, as opposed to the sharp mesio-incisal angle. This characteristic is even more pronounced in the maxillary lateral, so both of these teeth are not symmetrical in a labial or lingual view.

Front 81

The parotid duct is called A. Stensen's duct, and empties near the maxillary second premolar B. Wharton's duct and empties through the floor of the mouth C. Wharton's duct and empties near the maxillary second molars D. Stensen's duct and empties near the mandibular second molars E. Stensen's duct and empties near the maxillary second molars

Back 81

The correct answer is choice E. Stensen's duct empties the parotid gland into the buccal vestibule near the location of the buccal side of the maxillary second molar. Wharton's duct empties the submandibular gland, and some secretions from the sublingual gland, into the floor of the mouth underneath the tongue. The sublingual gland empties into the floor of the mouth through a series of openings in the plica sublingualis.

Front 82

The periodontal ligament fibers are primarily composed of which of the following connective tissues?A. HyalineB. ElasticC. CollagenousD. Fibrocartilagenous

Back 82

C. CollagenousThe correct answer is choice C. The periodontal ligament fibers are primarily composed of collagen. Hyaline cartilage is found on bone joint surfaces, in the trachea and nose, elastic connective tissue can be found in walls of arteries, and fibrocartilagenous tissue in many areas of the body. The collagen fibers of the periodontal ligament (known as principal fibers) connect the cementum of the tooth root to the alveolar bone.

Front 83

The premolar that most frequently has a single central pit is the1. maxillary first.2. maxillary second.3. mandibular first.4. mandibular second.

Back 83

4. mandibular second.The correct choice is 4. The mandibular second premolar typically has a Y-shaped groove pattern with mesial, distal and lingual grooves intersecting in a single central pit. The incorrect choices:Choice #I : The maxillary first pre-molar usually does not have a central pit, but a central groove with mesial and distal pits at each end. This is also true of choice #2, the maxillary second premolar, although a variation of the occlusal surface may be seen where the typical groove pit pattern is replaced by a single central pit. Choice #3: The mandibular first premolar typicaily has mesial and distal pits separated by the transverse ridge joining the buccal and lingual cusps.

Front 84

The primary maxillary canine is usually exfoliated between the ages of1. 6 and 7 years.2. 8 and 9 years.3. 10 and 11 years.4. 12 and 13 years.

Back 84

3. 10 and 11 years.The correct answer is choice 3. Primary maxillary canines are usually exfoliated between ages 10 and 11. Let's review exfoliation of other primary teeth. Primary central incisors are generally lost at approximately age 6 for mandibulars and age 7 for maxillaries. Laterals are lost at approximately 7 for mandibular and 8 for maxillaries. Canines are lost at about 10 for mandibular and 11 for maxillary. First molars are lost at approximately 10 for both arches and second molars at approximately 11 for both arches. As a general rule, mandibular teeth are lost first although they are at approximately the same time for the molars. So the correct answer to question is choice 3.

Front 85

Prominent cervical ridges or bulges are noted on which surfaces of primary teeth?A. Maxillary first molarB. Maxillary second molarC. Mandibular first molarD. Mandibular second molar

Back 85

C. Mandibular first molarThe correct answer is choice C. The primary mandibular first molar has the most prominent buccal cervical ridge. The "pot belly" is most visible as the tooth is viewed from the mesial side. It is also seen prominently on occlusal view as a bulge on the mesial-buccal.

Front 86

The primary purpose of dental pulp is:A. SensationB. ProprioceptionC. Enamel formationD. Dentin formationE. Inflammatory response

Back 86

D. Dentin formationThe correct answer is choice D. The odontoblasts, present in the outer layer of the pulp tissue, produce dentin. Dentin is the primary structural material of teeth, and attaches to both other dental tissues, cementum and enamel. No pulp means no dentin, and no dentin means no teeth! Some of the other functions listed are secondary. Sensation, in particular of pain, is a protective function, and can help prevent people from doing damage to the teeth. Proprioception, in general, is viewed as a protective response. Pulp can possibly be viewed as having a slight proprioceptive function. Proprioception is defined as the sense of position or space of a body part. Jaw position is determined partially by sensation of tooth contact, which is felt through the periodontal ligament, and to a lesser extent, through the pulp. This would hardly be the major function of pulp tissue. Enamel is formed by ameloblasts, not odontoblasts. Ameloblasts are never located in the pulp. Inflammatory response in the tooth pulp is brief and destructive, due to the confined space inside the pulp cavity. Little repair can occur through inflammation, and prolonged inflammation usually leads to pulpal necrosis. So inflammation is certainly not a major function of the pulp.

Front 87

The proximal contact of posterior teeth creates wear patterns that eventually cause1. gingival recession.2. increased length of clinical crowns.3. decreased length of anatomic crowns.4. reduced interproximal embrasure spaces.

Back 87

4. reduced interproximal embrasure spaces.The correct answer is choice 4. Slow gradual wear occurs interproximally at the contact point of adjacent posterior teeth. As this occurs over a lifetime, the mesiodistal width of the teeth become slightly less. The teeth become closer and the interproximal embrasure space becomes narrower. Choice 1 is incorrect because interproximal wear on teeth would not have a direct impact on gingival recession. Gingival recession is often related to periodontal disease andlor traumatic abrasion of the gingiva. Choices 2 and 3 are incorrect. Wear between teeth on the mesial and distal directions will not cause changes in occlusal or cervical height. As a reminder, anatomic crown is defined as the area of the tooth above the cementoenamel junction while clinical crown is that area of the tooth visible in the mouth above the gingival margin. Anyway, the correct answer to question is choice 4.

Front 88

The root tip most likely to be forced into the maxillary sinus during surgical removal is that of a1. maxillary first premolar.2. permanent maxillary canine.3. permanent maxillary first molar.4. permanent maxillary central incisor.5. primary maxillary second molar at age 12.

Back 88

3. permanent maxillary first molar.The correct answer is choice 3. Maxillary first molar roots are most in danger of entering the maxillary sinus. In general, the three teeth in the vicinity of the sinus are the second premolar. first molar and second molar. The first molar root is more likely to enter the sinus than roots of the other two teeth. Choices 1. 2 and 4 are all incorrect because they are not normally located near the sinus. Choice 5 is incorrect because a primary maxillary second molar which will be replaced by a permanent second premolar. It usually exfoliates by age 17 and if not exfoliated will certainly have most of its root resorbed by that age. So the correct answer to question is choice 3.

Front 89

The root tip MOST likely to be forced into the maxillary sinus during surgical removal is that of a maxillaryA. central incisor.B. canine.C. first premolar.D. first molar.

Back 89

A. central incisor.The correct answer is choice D. The maxillary sinus is a membrane lined air space found in the maxilla. The tooth nearest to the sinus in most people is the maxillary first molar. During extractions, a root of this tooth can sometimes be accidentally forced into the sinus through thin bone or membrane. Although a majority of tooth roots forced into the sinus are from the first molar, a small number are from the second molar, and an even smaller number from the second premolar. The other teeth listed are too far anterior.

Front 90

The spacing between anterior teeth in a 5-year-old child is MOST frequently caused byA. the presence of an excessive maxillary anterior frenum.B. the pressure from succedaneous teeth.C. thumb-sucking.D. tongue thrusting.E. the growth of the dental arches.

Back 90

E. the growth of the dental arches.The correct answer is choice E. Spacing is common in the primary dentition. Remember that the maxilla and mandible must both grow sufficiently to contain the larger size of the permanent dentition, as compared to the smaller primary dentition. The other choices listed CAN cause spacing. An excessive anterior frenum can prevent the maxillary anteriors from contacting. The pressure from permanent teeth erupting may move the primary teeth at various angles. Thumb sucking and tongue thrust can also move anterior teeth apart. However the MOST COMMON cause is normal arch growth to accommodate the permanent teeth.

Front 91

The spacing between anterior teeth in the primary dentition is most frequently caused by1. thumb-sucking.2. tongue thrusting.3. the growth of the dental arches.4. the pressure from succedaneous teeth.

Back 91

3. the growth of the dental arches.The correct answer is choice 3. Spacing between primary teeth and lack of contact between them is a natural, normal condition and not due to any parafunctional habits such as thumb sucking or tongue thrusting. So choices 1 and 2 are incorrect. As the arches grow in the child, the previously positioned anterior teeth will become farther apart and additional needed space for the wider permanent teeth will be provided. So choice 3 is correct. Choice 4 is incorrect. Succedaneous teeth are those permanent teeth which will eventually replace primary teeth. They include the incisors, canines and premolars. However, they do not pressure the primary dentition in any way which causes spaces between primary teeth. So the correct answer to question is choice 3.

Front 92

The tissue found above the condylar head and below the articular fossa of the TMJ is called theA. acapsuleB. temporomandibular ligamentC. articular diskD. sphenomandibular ligamentE. lateral pterygoid muscle

Back 92

C. articular diskThe correct answer is choice C. The articular disk is the piece of fibrous connective tissue that acts as a cushion between the condylar head and the articular (glenoid) fossa of the temporal bone. It also separates the upper and lower compartments of the joint. The articular capsule is the fibrous connective tissue structure that surrounds the entire joint structure. The temperomandibular ligament, also known as the lateral ligament, connects the capsule to the zygoma and neck of the mandible. The sphenomandibular ligament connects the sphenoid bone to the lingual and ramus of the mandible, whereas the stylomandibular ligament connects the styloid process of the temporal bone to the posterior border of the ramus. These two ligaments are sometimes assigned a slight protective function. The superior head of the lateral pterygoid muscle inserts into both the articular disk and capsule.

Front 93

The tooth showing the LEAST amount of anatomic variability is the:A. Maxillary third molarB. Mandibular first molarC. Maxillary lateral incisorD. Mandibular third molar

Back 93

B. Mandibular first molarThe correct answer is choice B. Mandibular first molars, like all teeth, have a significant number of anatomical variations. However, the other three teeth listed are considered to be the most variable in the mouth. Third molars have extreme varieties in crown shape, root shape, root number etc. They may look like first or second molars, or may be mere pegs. They are often missing. Variation in maxillary laterals is extreme as well, and is discussed in question 13. Mandibular first molar variations are less extreme. Some common ones include: 4 cusped instead of 5 (no distal cusp), and large extremely distally curved mesial roots. A rare variety may have 2 distal roots.

Front 94

The wear facets on the incisal edges of the mandibular lateral incisors are caused by occlusion with the1. maxillary central incisors only.2. maxillary central and lateral incisors3. maxillary lateral incisors and canines.

Back 94

2. maxillary central and lateral incisorsThe correct answer is choice 2. Mandibular lateral incisors are situated slightly mesially to the maxillary lateral. As a rule, the mandibular teeth are one half tooth mesial to the maxillary so the mandibular lateral will contact the mesial part of the maxillary lateral and the distal part of the maxillary central, both areas, of course, on the lingual surface of the maxillary teeth. So the correct answer to question is choice 2.

Front 95

What condylar movement is performed as the mandible moves from a pure protrusive movement from maximum intercuspal position to a maximum protruded position?A. TranslationB. RotationC. HingeD. ObliqueE. Medial and foward

Back 95

A. TranslationThe correct answer is choice A. The mandible moves by rotation around the axis of the temperomandibular joint and also by translation (movement of the whole body of the mandible). In protrusion, the lateral pterygoids act together to pull the mandible forward without rotation. Rotation is partly involved in both opening and in working movements, but not in protrusion.

Front 96

What is the most reliable and consistent way to distinguish maxillary first, second and third molars?A. number of cuspsB. size of the distobuccal cuspC. inclination of the rootsD. extent to which the roots are fusedE. size of the distolingual cusp

Back 96

E. size of the distolingual cuspThe correct answer is choice E. The maxillary molars differ from each other in several ways, although the general patterns of morphology are shared. As you go from 1st to 2nd to 3rd, the teeth become smaller in overall dimension. Most maxillary molars have four cusps, however, the first molar may have a 5th cusp, the Carabelli cusp. This cusp is sometimes large and cusp-like, but sometimes small and unnoticeable. It is sometimes referred to as the Carabelli trait, and is highly variable. The Carabelli trait can be found on the mesiolingual cusp. The third molar may sometimes have a distolingual cusp so reduced in size, that the tooth is essentially three-cusped. So, sometimes, the first, second and third molars might have 5,4, and 3 cusps respectively. This is not always the case, and cannot reliably differentiate between the teeth. Third molars commonly have fused roots, however, second and first molars rarely do. This will not distinguish all three molars from each other. Roots tend to incline more distally from 1st to 2nd to 3rd molar, however, this is not universally found. The most reliable way to distinguish the three molars is by the size of the distolingual cusp. The MB, ML and DB cusps in all maxillary molars form the trigon, or major cusp triangle. The distolingual cusp by itself, is the talon cusp, and gets progressively smaller from first to second to third molar. As stated previously, it may be absent in third molars.

Front 97

What is the most reliable and consistent way to distinguish maxillary first, second and third molars?A. number of cuspsB. size of the distobuccal cuspC. inclination of the rootsD. extent to which the roots are fusedE. size of the distolingual cusp

Back 97

E. size of the distolingual cuspThe correct answer is choice E. The maxillary molars differ from each other in several ways, although the general patterns of morphology are shared. As you go from 1st to 2nd to 3rd, the teeth become smaller in overall dimension. Most maxillary molars have four cusps, however, the first molar may have a 5th cusp, the Carabelli cusp. This cusp is sometimes large and cusp-like, but sometimes small and unnoticeable. It is sometimes referred to as the Carabelli trait, and is highly variable. The Carabelli trait can be found on the mesiolingual cusp. The third molar may sometimes have a distolingual cusp so reduced in size, that the tooth is essentially three-cusped. So, sometimes, the first, second and third molars might have 5,4, and 3 cusps respectively. This is not always the case, and cannot reliably differentiate between the teeth. Third molars commonly have fused roots, however, second and first molars rarely do. This will not distinguish all three molars from each other. Roots tend to incline more distally from 1st to 2nd to 3rd molar, however, this is not universally found. The most reliable way to distinguish the three molars is by the size of the distolingual cusp. The MB, ML and DB cusps in all maxillary molars form the trigon, or major cusp triangle. The distolingual cusp by itself, is the talon cusp, and gets progressively smaller from first to second to third molar. As stated previously, it may be absent in third molars.

Front 98

When alveolar bone fuses to the cementum of a root, it is known asA. geminationB. ankylosisC. hypercementosisD. gomphosisE. dilaceration

Back 98

B. ankylosisThe correct answer is choice B. Ankylosis refers to fusion or union of cementum to tooth root. Clinically, this may be important because ankylosed teeth are difficult to extract, and bone may be removed with the root. Additionally, ankylosed teeth often fail to fully erupt and sometimes remain below the plane of occlusion as the surrounding teeth erupt normally. Gemination refers to two tooth crowns emerging from one root. Hypercementosis is a nonpathological condition of additional cementum being deposited on a root surface. It does not fuse with bone, however. A gomphosis is the term for the immovable joint between tooth and alveolar bone. It refers to a normal, nonankylosed state. Dilaceration refers to a sudden change in direction of a tooth root.

Front 99

When anesthetizing the mandibular arch, the inferoir alveolar nerve block is usually performed. However, local infiltration may be effective. It is most likely to be effective in the area of the:A. MolarsB. PremolarsC. CaninesD. IncisorsE. Local infiltration is generally effective throughout the arch.

Back 99

D. IncisorsThe correct answer is choice D. The primary anesthetic injection for mandibular teeth for both restoration and extraction is the inferior alveolar nerve block. It is supplemented variously by the lingual nerve block, mental nerve block, long buccal nerve block or local infiltration. Local infiltration can occasionally be effective by itself in areas where thin bone (or very little bone) is present. The facial surface of mandibular incisors is composed of thin dentine and often is a site of periodontal disease, leaving even less bone than previously present. Extractions of mandibular incisors can sometimes be accomplished through local infiltraton alone. Mandibular bone is usually too thick in other areas of the arch.

Front 100

When compared with maxillary first premolars, the central developmental groove of maxillary second premolars isA. longer with less supplementary grooves.B. shorter with less supplementary grooves.C. longer with multiple supplementary grooves.D. shorter with multiple supplementary grooves.

Back 100

D. shorter with multiple supplementary grooves.The correct answer is choice D. One of the differences in the occlusal views of maxilary first and second premolars is the groove pattern. First premolars tend to have longer central grooves, few or no supplemental grooves, and a predictable groove pattern. Second premolars have shon central grooves (sometimes reduced to a pit), many supplemental grooves, and an unpredictable groove pattern. Sometimes the supplemental grooves will form an X radiating from the central pit-like groove. Other anomalies include an occasional distal transverse ridge.

Front 101

When hypoplasia of primary teeth is found but is limited to cusp tips and incisal edges of incisors, canines, and molars, it is most likely due toA. fluorosisB. insufficient systemic fluorideC. tetracycline intakeD. metabolic disturbance in embryonic periodE. metabolic disturbance in infancy

Back 101

D. metabolic disturbance in embryonic periodThe correct answer is choice D. Let's rule out choices. Fluorosis, or staining from excess systemic fluoride, is generalized discoloration and blotchiness throughout the enamel. Tetracycline staining is generalized yellow-brownish staining throughout the dentin and enamel (moreso dentin). There is no hypoplasia in either condition. Insufficient fluoride intake will affect caries susceptibility but does not have a distinctive clinical appearance. Hypoplasia is usually caused by a metabolic disturbance. The effect of the disturbance depends on timing. The crown tips and incisal edges of primary incisors, canines, and molars are formed from three to six months in utero, and crowns are completed during the first two (incisor) to 10 (second molar) months. So metabolic disturbances in infancy occur after the crown tips and incisal edges of these teeth are already formed.

Front 102

Which extrinsic muscle of the tongue functions to retract the tongue?A. HyoglossusB. StyloglossusC. GenioglossusD. Palatoglossus

Back 102

B. StyloglossusThe correct answer is choice B. Hyoglossus, attached to the hyoid bone, tends to pull the side of the tongue downward and also aids in retraction. With genioglossus, it can depress the tongue. Styloglossus is attached to the styloid process and stylomandibular ligament. It is the main retractor of the tongue, and can also elevate it. With genioglossus, it can raise the sides of the tongue and leave the middle depressed. Genioglossus connects to the mental spine of the mandible and can depress the tongue. Anterior fibers can retract the tongue tip while posterior fibers can protrude it. Palatoglossus attaches to the palatine aponeurosis. It can help to pull the posterior part of the tongue upwards.

Front 103

Which incisor is MOST frequently markedly concave on the lingual surface?A. Maxillary centralB. Mandibular centralC. Maxillary lateralD. Mandibular lateral

Back 103

C. Maxillary lateralThe correct answer is choice C. The maxillary lateral incisor is one of the most highly variable teeth in the mouth. It has a high incidence of being congenitally missing, can often appear in a peg form, and has a large variety of shape and size anomalies. A concave lingual surface is found commonly, and may range from small pit to deep depression. In clinical dentistry, large lingual pits or depressions on these teeth are sometimes restored with sealant or composite fillings.

Front 104

Which muscle is primarily involved when the mandible makes a RIGHT WORKING movement?A. Right medial pterygoidB. Left medial pterygoidC. Right lateral pterygoidD. Left lateral pterygoid

Back 104

D. Left lateral pterygoidThe correct answer is choice D. In a right working movement, the mandible moves to the right side. This movement occurs as the left lateral pterygoid pulls the left condyle forward while the right condyle stays stationary. In- general, lateral pterygoid muscles move the mandible forward (protrude) when acting jointly. They also act jointly to open the jaw (depress the mandible). When acting separately, the left lateral pterygoid moves the jaw right, while the right later pterygoid moves the jaw left. Medial pterygoids are closing muscles (elevators) and are not involved in protrusion or lateral movement.

Front 105

Which of the following anatomic features of a maxillary lateral incisor will most likely complicate root planing?1. A root bifurcation2. A mesial concavity3. A distolingual groove4. An extreme distal cervical line curvature

Back 105

3. A distolingual grooveThe correct answer is choice 3. In the maxillary lateral incisor, which is probably the most variable tooth in the mouth, a variation exists where a groove may cross from the cingulum over the mesial or distal margin onto the surface of the crown and down the mesial or distal surface of the root. This is known as a lingual marginal groove or distal lingual groove or mesial lingual groove. The groove is often deep and narrow and extremely difficult to scale or root plane. So choice 3 is correct. Choice 1 is incorrect as the maxillary lateral is invariably single rooted and does not contain a bifurcation. Choice 2 is incorrect. The maxillary lateral root does not normally possess a mesial concavity and if present, would not be as difficult to root plane as the narrow distal lingual groove. Choice 4 is incorrect. In general, the cervical curve of the lateral incisor is less than that of the central. However, the CEJ cervical line curvature does not have great significance for root planing. So the correct answer to question is choice 3.

Front 106

Which of the following BEST describes the Curve of Spee?A. The spherical configuration of the composite arrangement of the occlusal surfaces and incisal edges of the teeth of both dental archesB. The facial-lingual curvature resulting from the facial cusps being the longest in the mandibular arch, and the lingual cusps being the longest in the maxillary archC. The anterior-posterior curvature of the occlusal surfaces of the teeth, as seen in a facial viewD. The inclination of the teeth in relation to the vertical long axis of the bodyE. The composite arrangement of the facial crown surface heights of contour of all the teeth in any quadrant

Back 106

C. The anterior-posterior curvature of the occlusal surfaces of the teeth, as seen in a facial viewThe correct answer is choice C. The curve of Spee is an imaginary curve connecting the cusp tips of the mandibular teeth as seen from the lateral (facial side of the posterior teeth). The curve of Spee prevents protrusive interferences. The curve of Wilson is an imaginary curve connecting cusp tips as seen from the front of the face. This curvature helps to eliminate lateral interferences. These curves are part of a theory known as the spherical theory of occlusion.

Front 107

Which of the following best describes the root lengths of a maxillary molar?1. The lingual root is the longest and the distofacial root is the shortest.2. The lingual root is the longest and the mesiofacial root is the shortest.3. The mesiofacial root is the longest and the distofacial root is the shortest.4. All roots are the same length.

Back 107

1. The lingual root is the longest and the distofacial root is the shortest.The correct answer is choice 1. Maxillary molars are three rooted with mesial buccal or mesial facial, diaobuccal or distofacial, and palatal or lingual roots. Palatal is longest and generally curved and widest when viewed from the buccal or lingual. This is also termed flattened buccal lingually. The mesial buccal is second largest, not usually curved and widest when viewed proximally or mesiodistallly flattened. The distobuccal is usually shortest. So the correct answer to question is choice 1.

Front 108

Which of the following can adversely affect the self-cleaning quality of a dentition in normal alignment?A. Contact of adjacent teethB. Efficient use of a toothbrushC. Friction of food material during masticationD. Too great a contour of the cervical enamel ridge

Back 108

D. Too great a contour of the cervical enamel ridgeThe correct answer is choice D. Contact of adjacent teeth leads to a healthy self-cleansing of the teeth by preventing interproximal food impaction. Efficient use of a toothbrush will help the self-cleansing properties of teeth by aiding in plaque removal. Friction of rough or abrasive foods can also scrape plaque off of teeth. Prominent cervical enamel ridges or bulges can interfere with self-cleansing actions of the mouth by trapping plaque underneath the bulge, near the gingival margin. In prosthodontics, this is similar to overcontouring of prosthetic crowns which can lead to the same negative result.

Front 109

Which of the following characterizes a temporomandibular joint?1. It is immune to arthritis.2. It has one synovial cavity.3. It has two synovial cavities.4. It has no synovial cavities.

Back 109

3. It has two synovial cavities.The correct answer is choice 3. The temperomandibular joint has an unusual structure in which two compartments exist, an upper and a lower. The upper compartment exists in the area above the articular disk and below the articular or glenoid fossa. The lower compartment exists between the articular disk and the head of the mandibular condyle. Both compartments are synovial cavities in which synovial fluid eases the motion of the joint. In general, rotational movement is thought to involve primarily the lower compartment while translational movement involves primarily the upper compartment. Choices 2 and 4 are incorrect as noted already. Choice 1 is incorrect as arthritis is an occasional cause of TMJ pain and dysfunction. Arthritis is sometimes linked to trauma of the TMJ. So the correct answer to question is choice 3.

Front 110

Which of the following covers the articulating osseous structures of the temporomandibular joint?1. Synovial membrane2. Hyaline cartilage only3. Vascular fibrous connective tissue4. Dense avascular fibrous connective tissue5. Dense avascular elastic connective tissue

Back 110

4. Dense avascular fibrous connective tissueThe correct choice is 4. The articulating surfaces of the temporomandibular joint are covered by a dense avascular fibrous connective tissue. The articular disk is also made up of dense fibrous connective tissue. The incorrect choices: Choice #1: The synovial membrane forms the joint capsule of the temporomandibular joint and secretes the synovial fluid. Choice #2: The temporomandibular joint is one of very few joints in the body that does not have hyaline cartilage on its articular surfaces. The head of the condyle has some hyaline cartilage where bone growth takes place, under the articulating fibrous connective tissue. Choice #3: Vascular connective tissue makes up some of the periphery of the articular disk, but its main portion is avascular as is the fibrous connective tissue of the articulating surfaces. So, once again, the correct answer is 4.

Front 111

Which of the following groups of fibers of the periodontal ligament is most likely to be found in the middle third of the root?1. Apical2. Oblique3. Horizontal4. Transseptal5. Alveolar crest

Back 111

2. ObliqueThe correct answer is choice 2. Oblique fibers of the periodontal ligament are directed from the alveolar bone downward obliquely at an angle toward the cementum. They are found primarily in the middle third of the root. Choice 1, apical fibers, as the name implies are found primarily in the apical third of the root. Horizontal fibers which horizontally rather than obliquely connect bone to cementum are found primarily in the coronal third of the root. Transeptal fibers connect the cementum of two adjacent teeth above the level of alveolar bone and thus are also in the coronal third of the root. Finally, alveolar crest fibers connect obliquely from the coronal area of the cementum to the apical crest. They are also found in the coronal third of the root. So from the top down, our answers would be apical, middle, coronal, coronal, and coronal, and the correct answer to question is choice 2.

Front 112

Which of the following incisal angles of maxillary teeth exhibits the greatest convexity?A. Mesioincisal of the centralB. Distoincisal of the centralC. Mesioincisal of the lateralD. Distoincisal of the lateral

Back 112

D. Distoincisal of the lateralThe correct answer is choice D. It is best to view the term convexity as it refers to roundness, or an arc-like shape. In general both the mesio-incisal and disto-incisal line angles of the maxillary central incisor are more angular and less rounded than the corresponding line angles of the lateral. Within the lateral, the disto-incisal angle is more rounded than that of the mesio-incisal. Think of the maxillary lateral as a smaller more delicate and rounded version of the central.

Front 113

Which of the following incisors has its mesial and distal contact areas at the same incisocervical level?A. Maxillary centralB. Mandibular centralC. Maxillary lateralD. Mandibular lateral

Back 113

B. Mandibular centralThe correct answer is choice B. In maxillary centrals, the mesial contact (near the mesio-incisal line angle) is more incisal ( than is the distal contact. Likewise, in the maxillary lateral, the mesial contact is more incisal (near the junction of the incisal and middle thirds), while the distal contact is near the middle of the crown. The mandibular central incisor is generally symmetrical in crown shape when viewed from the labial, and this includes contact points which are both located in the incisal thirds. In the mandibular lateral, the distal contact area is more cervical.

Front 114

Which of the following is correct regarding the contact relationship of maxillary central incisors and maxillary lateral incisors?A. Contacts are centered faciolingually.B. Contacts are centered incisocervically.C. Facial embrasures are wider than lingual embrasures.D. lncisal embrasures are larger than gingival embrasures.

Back 114

A. Contacts are centered faciolingually.The correct answer is choice A. When viewed from the occlusal, the contact area of the maxillary central and lateral is centered in the labio-lingual direction. The contact is not centered inciso-cervically, being located more toward the incisal, at the junction of the incisal and middle thirds. Facial embrasures are fairly flat, while the lingual are deeper. Gingival embrasures extend up to the contact point, which is incisally located. Therefore they are larger than the rather small incisal embrasures, located incisal to the contact point.

Front 115

Which of the following is NOT found in mature pulp?A. neuronsB. blood vesselsC. leukocytesD. cells capable of forming primary dentinE. odontoblasts

Back 115

D. cells capable of forming primary dentinThe correct answer is choice D. Pulp is a connective tissue containing fibroblasts, blood vessels, nerves (carrying pain sensation), and odontoblasts. Since pulp contains blood vessels, it will also have leukocytes. Odontoblasts will line the perimeter of the pulp, and are capable of producing dentin. However, this dentin is of the secondary or reparative variety. Primary dentin is that which is first produced as the tooth is originally formed. Primary dentin cannot be produced by a mature pulp already inside a tooth.

Front 116

Which of the following is the first succedaneous tooth?A. Maxillary central incisorB. Mandibular central incisorC. Maxillary lateral incisorD. Mandibular first molar

Back 116

B. Mandibular central incisorThe correct answer is choice B. The definition of a succedaneous tooth is one that replaces another tooth. Therefore, all permanent molars are NOT succedaneous. The first primary tooth to be lost is generally the mandibular central, so the first succedaneous tooth is the permanent mandibular central incisor.

Front 117

Which of the following is the longest root?A. Root of a maxillary canineB. Root of a mandibular canineC. Lingual root of a maxillary first molarD. Lingual root of a maxillary second molarE. Mesial root of a mandibular first molar

Back 117

A. Root of a maxillary canineThe correct choice is 1. The maxillary canine has the longest root of any tooth in the dentition as you will find out when you try to extract one. It averages 17 millimeters from cemento-enamel junction to apex. Choice #2: The mandibular canine has an average cemento-enamel junction to apex root length of about 15 mm. Choices 3 and 4: The lingual roots of the maxillary first and second molars are the longest of the three roots in the molars and they average 12 and 11 mm, respectively. And choice #5: The mesial root of the mandibular first molar averages 14 mm. from CET to apex and is roughly the same length as the distal root.

Front 118

Which of the following jaw positions is determined almost exclusively by the behavior of the mandibular musculature?1. Postural2. Terminal3. lntercuspal4. Retruded contacting5. Protruded contacting

Back 118

1. PosturalThe correct choice is 1. The postural or rest position, where freeway space is present between the teeth, is primarily determined by the musculature. Choice #2: The terminal position is mostly determined by how far the condyle can go posteriorly in the articular fossa. Choices 3,4 and 5: Any position where the teeth are in contact is primarily determined by the teeth themselves.

Front 119

Which of the following jaw positions is determined almost exclusively by the behavior of the musculature? A. Postural B. lntercuspal C. Retruded contact D. Protruded contact

Back 119

A. PosturalThe correct answer is choice A. Three of the four positions listed are determined by a combination of muscular and dental factors. lntercuspal position is held in place by muscles in a position determined by the intercuspation (occlusion) of the two arches. The muscles may pull the mandible forward or backward into protruded or retruded contact positions, but the actual position is again determined by how the teeth intercuspate (occlude). Postural or rest position is determined by musculature alone. Teeth are slightly out of contact and the distance between the arches is determined by the habitual position or comfort level of these muscles.

Front 120

Which of the following ligaments has an outer oblique portion which limits the extent of jaw opening and initiates translation of the condyle down the articular eminence?A. CapsularB. CollateralC. StylomandibularD. Temporomandibular

Back 120

D. TemporomandibularThe correct answer is choice D. The temperomandibular (lateral) ligament reinforces the lateral aspect of the joint capsule. Its other functions include limiting the amount of opening, limiting the amount of retrusion, and due to its initial tautness, initiating the downward motion of the condyle. The capsular ligament surrounds the disc and synovial compartments of the joint. The stylomandibular ligament connects the styloid process and the ramus. The sphenomandibular ligament connects the sphenoid bone to the ramus. The function of these ligaments is not clear. They are sometimes referred to as collateral (accessory) ligaments.

Front 121

Which of the following maxillary teeth has the largest cervico-occlusal crown height?A. First premolarB. Second premolarC. First molarD. Second molar

Back 121

A. First premolarThe correct answer is choice A. The maxillary first premolar is notable for its large cervico-occlusal length (height). It is generally slightly larger than the second premolar. Both premolars are larger in height than the molars, which decrease in crown height from the first to the second to the third.

Front 122

Which of the following molars MOST frequently have only 3 cusps?A. Maxillary firstB. Mandibular firstC. Maxillary thirdD. Mandibular third

Back 122

C. Maxillary thirdThe correct answer is choice C. The maxillary third molar often lacks a distobuccal cusp. This cusp is generally smaller as one goes from the first to the second to the third molar. This leaves the third molar as a three cusped tooth. The maxillary first usually has four cusps, or five if a Carabelli cusp is present. The mandibular first usually has five cusps (including a small distal cusp). A mandibular third usually resembles the mandibular second in having 4 cusps (no distal cusp such as that on the first mandibular).

Front 123

Which of the following muscles is NOT an elevator of the mandible?1. Temporal2. Masseter3. Medial pterygoid4. Lateral pterygoid

Back 123

4. Lateral pterygoidThe correct choice is 4. The lateral pterygoid acts to help open or depress the mandible as well as being active in lateral mandibular movements. The digastric muscles also assist in depressing the mandible. Choices 1, 2 and 3: The temporal, masseter and medial pterygoid muscles all elevate or close the mandible.

Front 124

Which of the following normally describes the general crown form of canines when viewed from the facial or lingual aspect?A. 3-sidedB. 4-sidedC. 5-sidedD. 6-sidedE. 7-sided

Back 124

C. 5-sidedThe correct answer is choice C. The labial or lingual view of the maxillary canine crown form is pentagonal. The bottom of the pentagon is the CEJ. From the CEJ, the crown outline moves upward and outward on both the mesial and distal sides, until reaching the height of contour. Then, both sides turn inward and upward until reaching a point at the cusp tip.

Front 125

Which of the following normally describes the pulp cavity in a mesiodistal section of a maxillary canine?A. It exhibits 2 pulp horns.B. It is widest at its incisal limit.C. It is pointed at its incisal limit.D. It is widest at the midroot level.E. It is generally wider than in a faciolingual section.

Back 125

C. It is pointed at its incisal limit.The correct answer is choice C. The pulp of the maxillary canine, in mesio-distal section, will follow the outline of the tooth. It will be highest and pointed underneath the buccal cusp, and slant cervically downward toward both the mesial and distal directions. It is widest at about CEJ level, or slightly below, and will be considerably wider buccolingually than mesiodistally.

Front 126

Which of the following occurs when the distofacial cusp of a permanent mandibular right first molar moves through the facial groove from the central fossa of the maxillary right first molar?A. Direct lateral excursion to the leftB. Direct lateral excursion, to the rightC. Direct protrusive mandibular excursionD. Lateral-protrusive excursion to the leftE. Lateral-protrusive excursion to the right

Back 126

B. Direct lateral excursion, to the rightThe correct choice is #2, a direct lateral excursion to the right. The distofacial cusp of the right mandibular first molar occludes in the central fossa of the right maxillary first molar and moves through the facial groove of the maxillary first molar in a right lateral excursion.

Front 127

Which of the following permanent posterior teeth has a mesial marginal ridge that is located more cervical than its distal marginal ridge?1. Maxillary first premolar2. Maxillary second molar3. Mandibular first premolar4. Mandibular second molar

Back 127

3. Mandibular first premolarThe correct answer is #3, the mandibular first premolar. This is the only tooth that exhibits a mesial marginal ridge more cervically placed than the distal marginal ridge. The mandibular first premolar is also the only tooth where the occlusal table is not roughly parallel to the occlusal plane. The occlusal table is tilted so far lingually that virtually the whole table is visible when the tooth is viewed from the lingual.

Front 128

Which of the following permanent teeth normally have a mesiolingual groove?A. Maxillary canineB. Maxillary first molarC. Mandibular first molarD. Mandibular canineE. Mandibular first premolar

Back 128

E. Mandibular first premolarThe correct answer is choice E. The mandibular first premolar is the only tooth to have a mesiolingual groove. It is found between the mesial marginal ridge and the mesiolingual cusp ridge. It begins in the mesial pit and crosses the marginal ridge and onto the proximal surface. This trait is highly variable. Note that a similar groove is NOT found on the distal side of this tooth or on the mandibular second premolar.

Front 129

Which of the following positions would yield the smallest measurement of vertical dimension?1. Reverse overlap2. Edge-to-edge3. Retruded contact4. Maximum intercuspation

Back 129

4. Maximum intercuspationThe correct answer is choice 4. Maximum intercuspation or centric occlusion is the position in which the teeth are most fully contacted with each other. As such the jaws are most fully closed and therefore the vertical dimension is the least. Choice 1.2 and 3 as not being in maximum intercuspation or contact. are going to be slightly more separated and at greater vertical dimension. Choice 1. reverse overlap. refers to a protruded mandible position. Choice 2. edge to edge, refers to the meeting of the mandibular and maxillary anterior incisal edges. At this point. posterior teeth will be slightly separated. Choice 3. retruded contact or centric relation, is a mandibular position slightly posterior to maximum intercuspation. But again, slightly more separated and thus at slightly greater vertical dimension. So the correct answer to question is choice 4.

Front 130

Which of the following premolars frequently has only one pulp horn?1. Maxillary first2. Mandibular first3. Maxillary second4. Mandibular second

Back 130

2. Mandibular firstThe correct choice is 2. The mandibular first premolar has two cusps, but the lingual is so small that it usually has no pulp horn. The maxillary premolars, choices 1 and 3, have two well-developed cusps, each with its own pulp horn. The mandibular second premolar, choice 4, generally has three cusps and two pulp horns: buccal and lingual.

Front 131

Which of the following primary molars has an occlusal surface that most often bears the greatest resemblance to a premolar?1. Maxillary first2. Maxillary second3. Mandibular first4. Mandibular second

Back 131

1. Maxillary firstThe correct choice is 1. The primary maxillary first molar bears the closest resemblance to a premolar. There are usually three cusps, but the mesiobuccal and mesiolingual cusps are much more prominent than the distobuccal which may even be absent.The incorrect choices: Choice 442: The primary maxillary second molar resembles the permanent maxillary first molar from the occlusal. Choice #3: The primary mandibular first molar does not really resemble any of the permanent teeth. Choice #4: The primary mandibular second molar resembles the permanent mandibular first molar.

Front 132

Which of the following represents the geometric form of anterior teeth when viewed from the mesial or distal aspect?A. RhomboidalB. TrapezoidalC. EllipticalD. TriangularE. Square

Back 132

D. TriangularThe correct answer is choice D. Not a great question, in our opinion, however triangular is better than the rest. An incisor, when viewed from the mesial or distal can be viewed as roughly triangular, with one side the lingual slope, the second side the lingual edge of the root, and the third side made up of the entire buccal surface, both root and crown. Rhomboidal and square are definitely not correct, as they imply four equal sides, and elliptical is oval, with no distinct sides. Trapezoidal implies two parallel and two nonparallel sides, and this is not true for a mesial or distal view of an incisor. So while it might be stretching things a bit to see this I tooth view as triangular, it is still a better answer than the others.

Front 133

Which of the following represents the largest cusp of the mandibular first molar?A. DistalB. MesiofacialC. MesiolingualD. DistofacialE. Distolingual

Back 133

B. MesiofacialThe correct answer is choice B. The order of size of cusps in the mandibular first molars, from largest to smallest is:mesiobuccal, mesiolingual, distolingual. distobuccal and finally, distal. The distal can be remembered as the smallest simply by realizing that it is so small that it is often absent, so that one variety of mandibular first molar is a four cusped version. In mandibular second molars, cusps are much more equal in size.

Front 134

Which of the following represents the MOST common anatomic feature that complicates periodontal maintenance in a maxillary first premolar?A. Deep concavity on the mesial surface of the toothB. Intermediate furcational ridgeC. Mesiolingual developmental grooveD. Excessive convexity of the facial root

Back 134

A. Deep concavity on the mesial surface of the toothThe correct answer is choice A. On the mesial surface of the crown of the maxillary first premolar, there is a mesial developmental groove, which travels from the occlusal downward along the mesial crown surface, and then joins into the mesial root concavity, which extends down most of the mesial surface of the mesial root. This concavity often lends itself to plaque and calculus accumulation, overhanging restorations, and difficult cleaning of the area. Note that the mesiolingual developmental groove is found on the mandibular first premolar.

Front 135

Which of the following represents the normal eruption age (years) of the maxillary lateral incisors?A. 4-5 yearsB. 6-7 yearsC. 8-9 yearsD. 10-11 years

Back 135

C. 8-9 yearsThe correct answer is choice C. As a reminder, normal eruption times for the permanent incisors are: mandibular centrals at 6- 7 years. mandibular laterals at 7-8 years, maxillary centrals at 7-8 years and maxillary laterals at 8-9 years.

Front 136

Which of the following represents the tissue formed in response to stimuli produced by carious penetration of a tooth?A. PredentinB. Primary dentinC. Secondary dentinD. Interglobular dentin

Back 136

C. Secondary dentinThe correct answer is choice C. Secondary, or reparative, dentin, is formed in response to carious penetration or excessive mechanical stimulation (abrasion). It is sometimes viewed as a protective response. Predentin is non-mineralized precursor organic material laid down by odontoblasts. It is primarily collagen fibers. Primary dentin is all originally formed dentin in the tooth(excluding secondary dentin). Interglobular dentin refers to small uncalcified areas of dentin where collagenous matrix exists without mineralization.

Front 137

Which of the following roots is most likely to have a concavity on either or both its facial and lingual surfaces?1. Root of a maxillary second premolar2. Lingual root of a maxillary first molar3. Mesial root of a mandibular first molar4. Distal root of a mandibular second molar5. Mesiofacial root of a maxillary first molar6. Distofacial root of a maxillary first molar

Back 137

2. Lingual root of a maxillary first molarThe correct choice is 2. Of all the roots listed, only the lingual root of the maxillary first molar has a concavity on its lingual and/or facial surfaces. Choices 1, 3 and 4: The root of the maxillary second premolar and the mesial and distal roots of the mandibular molars are usually characterized by mesial and distal concavities down the sides of the roots. These concavities are most prominent on the maxillary second premolar and the mesial root of the mandibular molars. Choices 5 and 6: The mesiobuccal and distobuccal roots of the maxillary first molar generally do not exhibit any consistent concavities. They are slightly wider buccolingually than mesiodistally.

Front 138

Which of the following teeth has its mesial contact area located within the incisal or the occlusal one-third?1. Maxillary canine2. Maxillary first molar3. Mandibular second premolar4. Mandibular central incisor

Back 138

4. Mandibular central incisorThe correct answer is choice 4. The mesial surface of the mandibular central incisor contacts the mesial surface of the other mandibular central. They contact in the incisal third. All mandibular incisal contacts with each other or with the mesial of the canine are within the incisal third. Choice 1 is incorrect. Contact of the maxillary canine with the maxillary lateral incisor is in the middle third. Choice 2 is incorrect. Contact of the maxillary first molar with a maxillary second premolar is within the middle third. Choice 3 is incorrect. Contact of the mandibular second premolar with the mandibular first premolar is in the middle third. So the correct answer to question is choice 4.

Front 139

Which of the following teeth have long axes positioned with their root apices facial and their crowns lingual?A. Maxillary incisorsB. Mandibular incisorsC. Maxillary premolarsD. Maxillary molarsE. Mandibular molars

Back 139

E. Mandibular molarsThe correct answer is choice E. The question looks for teeth that lean lingually. That is, the root tips point facially, and the crowns lingually. In general, both maxillary and mandibular incisors have their root tips facing lingually and their crowns facially. (Opposite to what the question is looking for). Maxillary premolars generally are straight, and not buccally or lingually inclined. Maxillary molars, like the incisors, lean so that their crowns tip facially and root apices palatally. Only mandibular molars,of the teeth listed, tip in the lingual direction, with facially located roots.

Front 140

Which of the following teeth have sharp demarcations between pulp chambers and pulp canals?1. Mandibular canines2. Maxillary lateral incisors3. Maxillary first premolars4. Mandibular second premolars

Back 140

3. Maxillary first premolarsThe correct choice is 3. The maxillary first premolar generally has easily visualized beginnings of the pulp canals because 85% of the time, it has two canals, one each in the buccal and lingual roots. Choices 1. 2 and 4 are all single-rooted teeth, almost always with a single canal continuing apically from the pulp chamber. So it is difficult to see where the chamber ends and the single canal begins.

Front 141

Which of the following teeth in the permanent dentition normally have bifurcations?A. Mandibular caninesB. Mandibular second premolarsC. Maxillary molars and maxillary first premolarsD. Mandibular molars and maxillary first premolarsE. Maxillary first and second molars

Back 141

D. Mandibular molars and maxillary first premolarsThe correct answer is choice D. Bifurcations are divisions of roots or root trunks into two sections. We should be looking here for two rooted teeth. The mandibular canine is generally single rooted, as is the mandibuar second premolar. Maxillary molars are generally three-rooted. Mandibular molars are generally two-rooted. So our answer is mandibular molars and maxillary first premolars usually have bifurcations.

Front 142

Which of the following teeth in the permanent dentition normally have trifurcations?1. Mandibular molars only2. Mandibular second premolars3. Mandibular molars and maxillary first premolars4. Maxillary molars and maxillary first premolars5. Maxillary first and second molars and some maxillary third molars

Back 142

5. Maxillary first and second molars and some maxillary third molarsThe correct choice is 5. The maxillary molars are the only permanent teeth that normally have trifurcations. To have a trifurcation in the root trunk, three roots must be present. Choice #1: Mandibular molars. normally having two roots. therefore have a bifurcation. Choice #2: Mandibular second pre-molars normally are single rooted. Choices #3 and 4: Maxillary first premolars usually have two roots and a bifurcation, although the bifurcation may be well down the roots towards the apices of the roots.

Front 143

Which of the following teeth is MOST likely to have a distal coronal concavity that can pose special problems in matrix placement?A. Maxillary first premolarB. Mandibular first premolarC. Maxillary first molarD. Mandibular first molar

Back 143

C. Maxillary first molarThe correct answer is choice C. The maxillary first molar may show a slightly flattened section of the crown in the cervical third of the distobuccal area. Note that the maxillary first molar often has a mesial concavity, as does the mandibular first molar, with a coronal concavity extending down to and meeting a root concavity.

Front 144

Which of the following teeth would most likely be congenitally absent?1. Maxillary canine2. Mandibular canine3. Maxillary central incisor4. Mandibular central incisor5. Maxillary lateral incisor6. Mandibular lateral incisor

Back 144

5. Maxillary lateral incisorThe correct answer is choice 5. The most commonly congenitally missing tooth is the maxillary lateral incisor, choice 5. Others include third molars, either maxillary or mandibular and second premolars, maxillary or mandibular. Canines are rarely congenitally missing. A general rule related to this question is that congenitally missing teeth are usually the distal teeth of a certain I type, that is the lateral incisors more often than the central, second premolars more than first premolar and the third molars more than the other molars. Anyway, the correct answer to question is choice 5.

Front 145

Which position of the mandible is determined primarily by tooth position?A. intercuspalB. centric relationC. physiologic restD. retruded contact

Back 145

A. intercuspalThe correct answer is choice A. Intercuspal position is also centric occlusion. The teeth are in contact and the mandible is neither protruded nor retruded. There is no leeway space (space between the teeth). The position centric relation and the position retruded contact are positions sometimes used in prosthodontics to give a reproducible jaw relation. The mandible is pushed slightly backwards to where the condyle is in its most posterior position. This position is determined by the condyle, muscles, teeth and the dentist. Retruded contact is generally a few millimeters distal to centric occlusion. Physiologic rest is the position of the mandible when the jaws are at rest. Teeth are generally slightly separated and the amount of separation is determined by the comfortable stretch or contraction of the facial muscles. The position is thus determined primarily by soft tissue and not by teeth.

Front 146

Which premolar has a facial cusp with a triangular ridge so uniquely prominent as to frequently separate its mesial pit from its distal pit?A. Maxillary firstB. Mandibular firstC. Maxillary secondD. Mandibular second

Back 146

B. Mandibular firstThe correct answer is choice B. The triangular ridge is the surface inclining downward from the buccal and lingual cusps of the premolars. In the mandibular first premolar, these ridges are often very prominent, meet in the middle and become a pronounced transverse ridge, which separates the mesial from the distal half of the tooth. This transverse ridge is unique to the mandibular first premolar.

Front 147

Which premolar is the largest?A. mandibular firstB. mandibular secondC. maxillary firstD. maxillary second

Back 147

C. maxillary firstThe correct answer is choice C. In general, the premolars are very similar in overall size. All four premolars are similar in mesial-distal width, and the maxillary premolars are larger than the mandibulars in buccal- lingual width. Between the two maxillary premolars, the major difference is in overall tooth length, including root. The first premolar is approximately 1mm longer on average.

Front 148

Which premolar MOST likely possesses a crescent-shaped central developmental groove?A. Maxillary firstB. Mandibular firstC. Maxillary secondD. Mandibular second

Back 148

D. Mandibular secondThe correct answer is choice D. The mandibular second premolar often contains a Y shaped or crescent shaped central developmental groove. The three variations of the central groove pattern of this tooth are often referred to as the Y, H and U patterns. The mandibular first premolar tends to have no central pit, and lacks the Y shaped developmental central groove. The maxillary first tends to have a longer straight central groove with few supplementary grooves, while the maxillary second usually has a shorter central grove with more supplementary grooves.

Front 149

Which primary tooth most closely resembles its successor?A. Mandibular first molarB. Maxillary second molarC. Mandibular central incisorD. Maxillary first molarE. Mandibular second molar

Back 149

C. Mandibular central incisorThe correct answer is choice C.

Front 150

Which root is most likely to have a divided root canal?A. Maxillary central incisorB. Mandibular central incisorC. Maxillary canineD. Mandibular canine

Back 150

D. Mandibular canineThe correct answer is choice D. Maxillary central incisors, mandibular central incisors and maxillary canines almost invariably have single roots. Maxillary centrals and canines generally have a single root canal within the single root. Mandibular centrals may have two canals, but usually have one apical foramen. The mandibular canine is the most likely of the group to have two roots and/or two canals within the one or two roots.

Front 151

Which teeth usually have trifurcations?A. maxillary and mandibular molarsB. maxillary molars and premolarsC. maxillary first, second and sometimes third molarsD. mandibular first, second and sometimes third molarsE. None. Teeth can have bifurcations but not trifurcations

Back 151

C. maxillary first, second and sometimes third molarsThe correct answer is choice C. This is a basic definition question. The term trifurcation refers to the area where any three roots join together. This is opposed to the more common term bifurcation found wherever two roots come together. Only a three rooted tooth can have a trifurcation, so maxillary molars should immediately come to mind. The area underneath the common root trunk where the mesiobuccal, distobuccal and palatal roots meet is the trifurcation.

Front 152

Which tooth can almost always be rotated during extraction, without danger of fracturing the root?A. Mandibular canineB. Maxillary first premolarC. Maxillary second premolarD. Mandibular first premolarE. Maxillary central incisor

Back 152

E. Maxillary central incisorThe correct answer is choice E. In extraction, teeth with conical or rounded roots can be extracted with a rotational movement in addition to buccal-lingual luxation. You should avoid this movement with any teeth likely to have two roots, either separate or fused. Many teeth may have one root, but it is more flattenned than round, or a usually one rooted tooth may occasionally have two roots. The mandibular canine is generally one rooted, but may have two roots occasionally, with a split into buccal and lingual sections near the apex. Its root may also be somewhat flattened. Maxillary first premolars generally have two roots and are never rotated. MaxiHary second premolars are usually one-rooted, but the root may be ovalish or flattened rather than round. Mandibular first premolars are usually one rooted, occasionally double rooted, and the root is often flattened. Maxillary central incisors invariably have one root, usually oval or rounded. There is rarely a complication when they are rotated during extraction.

Front 153

Which tooth has the greatest mesio-distal diameter?A. Mandibular first molarB. Maxillary second molarC. Mandibular central incisorD. Maxillary second molar

Back 153

A. Mandibular first molar The correct answer is choice A. The permanent mandibular first molar is the largest tooth in the mesiodistal direction. In general, the mandibular molars are wider mesiodistally than their maxillary counterparts. The mandibular first molar is slightly longer than the mandibular second molar, partially due to the presence of a fifth cusp, the distal cusp. This cusp is absent in the second molar. It should be noted that within the molars, in general, size decreases from 1st to 2nd to 3rd within both arches.

Front 154

A 17-year-old patient has periodontitis involving the anterior teeth with sparse plaque. Which of the following is the probable primary pathogen?A. Actinobacillus actinomycetemcomitansB. Bactemides forsythusC. Fusobacterium nucleatumD. Porphyromonas gingivalisE. Prevotella intermedia

Back 154

ACTINOBACILLUS ACTINOMYCETEMCOMITANSThe correct answer is choice A. Adult chronic periodontitis is usually associated with calculus, plaque, inflammation and anaerobic organisms within the periodontal pocket. These organisms include Bacteroides, Fusobacteria, Porphyromonas, and Prevotella. In this case, however, the young age of the patient, and the absence of plaque and calculus indicate a different disease. Juvenile periodontitis has a site predilection for incisors and first molars. It is usually very fast in progression, and not associated with high plaque and calculus levels. Its main cause is the organism Actinobacillus actinomycetemcomitans, also mercifully known as "aa". So the correct answer to question is choice A.

Front 155

A 17-year-old patient has periodontitis involving the anterior teeth with sparse plaque. Which of the following is the probable primary pathogen?A. Actinobacillus actinomycetemcomitansB. Bactemides forsythusC. Fusobacterium nucleatumD. Porphyromonas gingivalisE. Prevotella intermedia

Back 155

The correct answer is choice A.Actinobacillus actinomycetemcomitans Adult chronic periodontitis is usually associated with calculus, plaque, inflammation and anaerobic organisms within the periodontal pocket. These organisms include Bacteroides, Fusobacteria, Porphyromonas, and Prevotella. In this case, however, the young age of the patient, and the absence of plaque and calculus indicate a different disease. Juvenile periodontitis has a site predilection for incisors and first molars. It is usually very fast in progression, and not associated with high plaque and calculus levels. Its main cause is the organism Actinobacillus actinomycetemcomitans, also mercifully known as "aa". So the correct answer to question is choice

Front 156

A 65-year-old man who experiences urinary retention or difficulty in voiding his bladder most likely has1. carcinoma of the prostate.2. benign prostatic hyperplasia.3. malignant neoplasm involving the urethra.4. bladder metastasis of bronchogenic carcinoma

Back 156

The correct choice is choice 2, benign prostatic hyperplasia. Benign prostatic hyperplasia or BPH is so common that it is considered by some to be a normal consequence of aging. Half of men over the age of 50 have BPH and almost all men over the age of 70 have BPH. BPH is characterized by the formation of nodules in the prostatic tissue surrounding the prostatic urethra. When these nodules enlarge, urinary obstruction often follows. Most obstruction is partial obstruction. It causes voiding difficulty. The individual cannot fully empty his bladder and he must make frequent trips to the restroom. Complete obstruction may also occur. The individual rapidly develops hydronephrosis and acute renal failure. This is a life-threatening condition as the renal failure become less and less reversible as time elapses. Carcinoma of the prostate, choice 1, rarely causes urinary retention. The carcinoma arises in the lateral lobes of the prostate. It must reach very large proportions to compromise the prostatic urethra which is located centrally. Malignant neoplasms of the urethra, choice 3, may cause urinary retention. These lesions are extremely rare, however. Bronchogenic carcinoma. choice 4, may metastasize to the bladder. However, metastatic lesions and primary tumors of the bladder usually cause hematuria rather than urinary retention. Once again, the correct choice to question is choice 2

Front 157

A benign neoplasm of the myometrium of the uterus is a1. myeloma.2. fibroma.3. leiomyoma.4. myoblastoma.5. rhabdomyoma

Back 157

Leiomyoma, or fibroid tumors, are benign smooth muscle neoplasms of the uterus and are the most common tumor in women. They rarely transform into malignant tumors. Myelomas, choice 1, are plasma cell dyscrasias with multiple plasma cell tumors scattered throughout the body. Choice 2, fibromas, are tumors of connective tissue often found in ovaries, but not myometrium of the uterus. Choice 4, myoblastomas, are benign circumscribed lesions of soft tissue often found in the tongue but not of muscular origin. They possibly arise from Schwann cells. Choice 5, rhabdomyomas, are benign cardiac muscle tumors usually seen in children. So the correct answer to question is choice 3.

Front 158

A can of disinfectant spray states that it kills HIV virus. This statement:A. Is important because of the difficulty in killing this virusB. Shows that the disinfectant will kill most other pathogensC. Illustrates the use of a "benchmark" organismD. Is not a good indication of disinfectant effectiveness

Back 158

The correct answer is choice D. Not a good indicator. HIV virus is notoriously easy to kill on most environmental surfaces. Many disinfectants, and other common physical and chemical exposures will kill the virus fairly easily. Therefore, ability to kill HIV is NOT an important criterion in choosing disinfectants. Mycobacterium tuberculosis is chosen as the "benchmark organism" (the standard against which the disinfectant is compared). It is very resistant to surface disinfectants, partially due to its waxy cell wall. Another highly resistant pathogen on environmental surfaces is Hepatitis A virus.

Front 159

A common oral manifestation of Addison's disease is1. melanosis.2. xerostomia.3. glossodynia.4. "cotton-wool" bone.5. loss of lamina dura

Back 159

The correct choice is answer #1, melanosis. Addison's disease is the term used for adrenal insufficiency of any etiology. Adrenal insufficiency may be primary due to autoimmune phenomena, tuberculosis infiltration, metastatic tumor or amyloidosis, or it may be secondary due to abnormalities of the hypothalamus or pituitary, or exogenous administration of steroids. In primary adrenal insufficiency, feedback inhibition of adrenal hormones on the hypothalamus and pituitary is lost. Consequently, the production of adrenocorticotropic hormone (ACTH) is increased. Linked to ACTH production is the production of melanotropin and this hormone causes pigmentation of the skin and mucous membranes in a phenomenon known as melanosis. Xerostomia, choice 2, means dry mouth. It can be seen in a variety of diseases, but is most common in Sjogren's disease and other rheumatologic illnesses. Glossodynia, choice 3. means painful tongue. This can result from a local burn or trauma or from metastatic tumor infiltration of the lingual nerve. The term "cotton wool bone", choice 4, describes the radiographic appearance of bone in Paget's disease. Paget's disease is a metabolic disorder of bone characterized by an increased rate of bone resorption coupled with new bone synthesis. The lamina dura, choice 5, is a thick layer of tissue lining the dental alveolar bone. This tissue is lost in periodontal disease, but is uninvolved in Addison's disease. Once again, the correct choice to question is choice 1.

Front 160

A complication of peptic ulcer disease that accounts for the majority of deaths is1. bleeding.2. perforation.3. surgical complication.4. malignant transformation.5. obstruction from edema or scarring

Back 160

The correct answer is choice 2. Perferation. Peptic ulcers are chronic isolated ulcers in areas of the esophagus, stomach or duodenum bathed by pepsin and HCL, and are the result of lowered mucosal resistance. The major complications of peptic ulcers include hemorrhage, perforation, obstruction and pain. Malignant transformation, choice 4, is rare in stomach ulcers and unknown in duodenal ulcers, and so is incorrect. Bleeding, choice 1, is a common problem with ulcers, but does not account for the majority of deaths, which is what the question is looking for. Perforation, in which the ulcer grows until it is completely open through the outer wall of the stomach and into the peritoneal cavity, is a serious medical problem and may cause death, and it is our correct answer. Choice 3 is incorrect. Most ulcers are not surgically treated and those that are do not commonly result in death through surgical complications, so it is not the most common cause of death. Likewise, in choice 5, obstruction may occur but does not lead to death as often as does perforation. So the correct answer to question is choice 2.

Front 161

A deficiency in which of the following cell types is most associated with the development of oral candidiasis?A. NeutrophilsB. T-lymphocytesC. B-lymphocytesD. Plasma cellsE. Macrophages

Back 161

The correct answer is choice B. T lymphocyes. This question indirectly links immunodeficiency, such as that found in HIV disease, and the development of candidiasis. The major target cells of HIV virus are the T-lymphocytes, specifically the T4 (CD4) type. As the T-lymphocyte count drops, numerous opportunistic infections occur, including the one most familiar to dentists, oral candidiasis. All of the cells listed are leukocytes and are involved in protective and immune responses, However, the T-lymphocyte population is most heavily damaged and most involved in keeping normal levels of Candida from growing out of control. Remember that B-lymphocytes are most involved in humoral immunity, and T-lymphocytes in cell mediated immunity. Some B-lymphocytes become plasma cells, which secrete antibodies. Macrophages and neutrophils are phagocytic, among other functions

Front 162

A fungus that causes systemic disease, most commonly of the lungs, and is characterized by its production of tubercolate chlamydospores in culture isA. Microsporum canis.B. Mycoplasma hominis.C. Leptospira pomona.D. Actinomyces israelii.E. Histoplasma capsulatum

Back 162

The correct answer is choice E. Histoplasmosis capsulatum transmission is mediated by airborne inhalation of spores that get deposited in alveoli and spread through lymphatics to the regional lymph nodes. Clinical manifestations include acute and chronic pulmonary infections that very rarely progress to a disseminated histoplasmosis. Choice A - Microsporum canis is incorrect. Choice B - Mycoplasma hominis is a sexually transmitted agent and is a major source of infection in postpartum women. Choice C - Leptospira pomona is caused by ingestion or contact through broken skin or mucous membranes with water contminated by urine from infected reservoirs (dogs, sheep, goats cattle, horses, & rats). Choice D - Actinomyces israelii are part of the normal oral flora and are usually pathogenic only after oral trauma. Therefore the correct answer to question is E.

Front 163

A grayish pseudomembrane is found in an infection caused by a species of:A. StreptococcusB. CorynebacteriaC. StaphylococcusD. Pseudomonas

Back 163

The correct answer is choice B. Corynebacteria include the pathogen C. diphtheriae, which causes diphtheria. In particular, the bacteria excrete an exotoxin that causes the disease. Diphtheria is spread by droplets, and the peptide exotoxin is absorbed by epithelia, and the necrotic epithelium, fibrin, and blood cells form the familiar "pseudomembrane." The pseudomembrane covers the pharynx and tonsils, and the toxin produced there may do distant damage to liver, kidneys and heart, etc

Front 164

A lesion on which of the following nerves would not affect the gustatory pathway?A. VB. VIIC. VIIID. IXE. X

Back 164

Cranial nerve VIII (choice C) or the vestibulocochlear nerve is the only cranial nerve listed that is not associated with the gustatory pathway. Damage to this nerve during a surgical procedure would not affect any aspect of the gustatory pathway. The vestibulocochlear nerve is primarily associated with balance, equilibrium and hearing. Cranial nerve V or the trigeminal nerve (choice A) provides information concerning the general texture of food as well as the taste-related sensations of peppery or hot. The taste buds are monitored by cranial nerves VII (Facial) (choice B), IX (Glossopharyngeal) (choice D), and X (Vagus) (choice E). The sensory afferents of these nerves synapse within the nucleus solitarius of the medulla oblongata and the axons of the postsynaptic neurons enter the medial lemniscus, which join axons carrying somatic sensory information. This type of sensory information is related to touch, pressure and propioception

Front 165

A mother states that when she feeds or bathes her newborn, the infant becomes cyanotic; however, the baby appears normal the rest of the time. What is the most likely cause of the infants signs and symptoms?A. AnemiaB. AsthmaC. Patent ductus arteriosusD. SepticemiaE. Upper respiratory infection

Back 165

The correct answer is C. Congenital circulatory problems are normally associated with an abnormal formation of the heart or problems with the interconnection between the heart and the major blood vessels. For example, the incomplete closure of the ductus arteriosus results in the bypassing of the lungs and the recirculation of blood into the systemic circuit. Since normal oxygenation of the blood does not continually occur, the infant can become cyanotic during of stress. When the baby is eating or bathing, blood is shunted to the stomach or skin respectively. When these stressful events are NOT occurring, there is sufficient blood flow to the lungs to prevent cyanosis. Although there are several kinds of anemia (choice A), the classic signs and symptoms of this condition are chronic fatigue and tachypnea on exertion. Asthma (choice B) is characterized by chronic (or episodic) wheezing, dyspnea and cough. Septicemia (choice D) is defined as a severe systemic infection. If the child had septicemia, she would not appear normal most of the time; the infant would appear very lethargic, hyperthermic and "septic." If the infant had an upper respiratory infection (choice E), the child would most likely appear weak, lethargic and would be coughing.

Front 166

A neoplasm composed of all three germ layers is referred to as a(n):A. adenomaB. osteomaC. teratomaD. sarcomaE. carcinoma

Back 166

The correct answer is choice C. Simple neoplasms arise from one cell type or germ layer. Mixed neoplasms arise from two, and teratomas ("monster growths") arise from all three and often have a bizarre appearance. Cancers arising from epithelium or endoderm are usually called carcinomas (choice E), whereas those originating from mesoderm are called sarcomas (choice D). An adenoma (choice A) is a benign epithelial tumor, and an osteoma (choice B) is a benign bone tumor

Front 167

A patient with dentinogenesis imperfecta has a history of multiple fractures. Examination reveals blue sclera. The most probable diagnosis is1. achondroplasia.2. Marfan's syndrome.3. osteogenesis imperfecta.4. Albers-Schonberg disease

Back 167

Osteogenesis imperfecta is a hereditary disease of collagen metabolism. It is characterized by thin deformed bones, blue sclera, fractured ear ossicles, malformed discolored teeth, and mitral valve prolapse. Choice 1 is incorrect. Achondroplasia refers to a hereditary disease of impaired cartilage formation, poor long bone formation and dwarfism. Choice 2 is also incorrect. Marfan's syndrome is a hereditary connective tissue disease, possibly due to defective elastin in ground substance. Clinically, it may involve aortic aneurysm, mitral valve prolapse, or subluxed lens. Choice 4. Albers-Schonberg disease is another term for osteopetrosis, a rare hereditary disease characterized by abnormally dense bone due to defective resorption of immature bone. So the correct answer to question is choice 3

Front 168

A patient with facial erythema, fever, Raynaud's phenomenon, joint pain and photophobia probably has1. scleroderma.2. Paget's disease.3. Sjögren's syndrome.4. erythema multiforme.5. systemic lupus erythematosus

Back 168

The correct choice is choice 4, systemic lupus erythematosus. Systemic lupus erythematosus or SLE is an autoimmune disease primarily affecting women. Antibodies to a host of nuclear and cytoplasmic antigens develop as in other autoimmune diseases. The most specific marker of SLE, however, is antibody directed against double-stranded DNA. The anti-nuclear and anti-cytoplasmic antibodies are responsible for many manifestations of the disease. They deposit as antibody antigen complexes in the kidneys, joints, and blood vessels, and activate complement. Tissue destruction then ensues. In addition to the symptoms mentioned in the question, an individual with SLE may suffer from hematuria, proteinuria, nephrosis, pericarditis, pleuritis, lymphadenopathy, leukopenia, thrombocytopenia, and decreased cognition. The disease tends to be chronic with intermittent exacerbations and remissions. Exacerbations require steroid therapy to minimize tissue destruction. Scleroderma, choice 1, is also an autoimmune disease. Many anti-nuclear and anti-cytoplasmic antibodies can be isolated in affected individuals, the most specific of which are antibodies against centromeres and nonhistone nuclear proteins. This disorder is characterized by extensive fibrosis involving the skin and viscera. It begins with thickening of the hands and arthritis. As it progresses, the esophagus thickens, causing dysphagia. The disease may also involve the lungs, leading to pulmonary fibrosis; tke lower GI tract, and the kidneys. Paget's disease, choice 2, is a very common, usually asymptomatic, disease of bone characterized by bone destruction, with excessive bone reformation. When symptoms do occur, they usually include musculoskeletal pain, pathologic fracture, and skeletal deformity. The etiology of Paget's disease is not known. Sjogren's disease, choice 3, is another autoimmune phenomenon. The most specific marker of this disease is antibody called SSB E which is directed against an extractable nuclear antigen. Clinically, Sjogren's disease is characterized by the sicca syndrome which includes dry mouth and dry eyes caused by lymphocytic infiltration of the salivary and-lacrimal glands. Sjogren's disease is commonly associated with rheumatoid arthritis or SLE, but by itself is not a disseminating disease. Erythema multiforme, choice 4, may be associated with SLE, but more commonly it represents a hypersensitivity reaction to drugs or infectious agents. It is characterized by a maculopapular rash which develops into a bullous process. Erythema multiforme is uncommon and self-limited. Once again, the correct choice to question is choice 5.

Front 169

A patient, with which of the following disease states, is at the highest risk for development of an oral infection following a tooth extraction?A. Congestive heart failureB. DepressionC. Diabetes mellitusD. HypertensionE. Hyperthyroidism

Back 169

The correct answer is C. Diabetes mellitus is a disease characterized by polyuria, polydipsia, ketonemia, and/or ketonuria. Complications of this disease are caused by prolonged periods of blood glucose levels greater than 126 mg/dL. Patients with diabetes mellitus are at an increased risk for post-operative infections and impaired wound healing secondary to the sustained periods of hyperglycemia as well as the circulation problems commonly seen in diabetic patients. Therefore, of the diseases listed, patients with diabetes mellitus are at the highest risk for infectious complication and impaired wound healing following a surgical procedure. Congestive heart failure (choice A) is a condition characterized by an abnormality of cardiac function. In this condition, there is a failure of the heart to pump blood throughout the body at a rate sufficient to meet the requirements of the metabolizing tissues and/or the heart is only able to meet these requirements when the end-diastolic volume is abnormally elevated. This disease is not associated with an increased development of oral infections. Depression (choice B) is a psychiatric disorder where patients have prolonged feelings of hopelessness, sadness, worthlessness, and changes in appetite and sleep behavior. Often, these patients relate feelings of anxiety or guilt and have difficulty thinking or concentrating; suicidal ideation may also be present. Although patients with psychiatric disorders are more prone to inflict self-injury, their ability to heal following a surgical procedure is not impaired. Hypertension (choice D) is a disease associated with high blood pressure. Over 50 million Americans have this disease and the majority of them experience no impairment of wound healing following a surgical procedure. Hyperthyroidism (choice E) is an endocrine disorder characterized by sweating, weight change, nervousness, irritability and fatigue; this hypermetabolic disorder is generally NOT associated with impaired wound healing. However, a patient with hypothyroidism will commonly experience some degree of impairment of wound healing following a surgical procedure.

Front 170

A person with anti-A and anti-B isoagglutinins in the serum belongs to blood group1. A2. B3. AB4. O

Back 170

The correct choice is choice 4, 0. Isoagglutinins are antibodies which cause clumping of cells. These antibodies are not normally present in all individuals. They are only present in those individuals who lack the specific antigens with which the antibodies react. Blood is typed on the basis of the antigens present on the red cell membrane. Type A blood cells, for example, have A antigen on their surface. An individual with type A blood has antibody to B antigens. Individuals with type AB blood have both A and B antigens. They have no anti-A or anti-B antibodies in their serum. If they did, they would agglutinate their own red cells. Type 0 blood cells have no antigens of the A or B class on their surface. Individuals with type 0 blood have anti-A and anti-B antibody in their serum. Consequently, type 0 individuals may only receive type 0 blood during a transfusion. The lack of A and B antigens on the surface of type 0 red blood cells enables type 0 individuals to donate blood to individuals of any blood type. Type 0 individuals are consequently called universal donors, while type AB individuals are termed universal recipients. Once again, the correct choice to question is choice 4.

Front 171

A positive skin test in an individual who has had tuberculosis is an example of1. atopy.2. autoimmunity.3. hypersensitivity.4. passive immunity

Back 171

The correct choice is choice 3, hypersensitivity. When tuberculin is injected into an individual who has had TB in the past, delayed type hypersensitivity results. In this reaction, memory T-lymphocytes recognize the tuberculin, which is a protein lipopolysaccharide extract of the Mycobacterium, and these T-lymphocytes secrete lymphokines. Lymphokines are chemicals which attract macrophages and other mononuclear inflammatory cells to the site. Within 24 hours, fibrin is deposited, leading to induration; vascular permeability is increased, leading to edema; and vasodilatation causes erythema. Atopy, choice 1, is an acute reaction. Here, sensitized mast cells are coated with IgE molecules. When these molecules are cross-linked by the introduction of antigen, degranulation of mast cells results. Histamine is released which causes bronchospasm and bronchial edema, as are various chemotactic agents which bring eosinophils and neutrophils to the site. Common antigens causing atopy include ragweed and drugs. Autoimmunity, choice 2, is the phenomenon responsible for diseases such as systemic lupus erythematosus or myasthenia gravis. In these diseases, the body produces immunoglobulins against host tissue. In lupus, antibodies against nuclear and ribosomal proteins are formed. In myasthenia gravis, antibodies against acetylcholine receptors are produced. Passive immunity, choice 4, refers to the process whereby immunoglobulins from one host are transferred to another host in whom they confer protection. Passive immunity was the primary immunization strategy utilized by the medical community prior to the advent of vaccines. Passive immunity continues to play a fundamental role in the protection of newborns. IgG is transferred from the mother to the fetus through the placenta and from the mother to the newborn through breastfeeding. The infant depends on these immunoglobulins to fend off infection during the first six months of life, while the infant's immune system is maturing. Once again, the correct choice to question is 3.

Front 172

A summer illness that produces vesicular lesions of the uvula, anterior pillars and the posterior pharynx is1. influenza.2. herpesvirus.3. ECHO virus.4. coxsackievirus

Back 172

The correct answer is choice 4. Coxsackie viruses are enteroviruses that produce a variety of illnesses in humans. Herpangina is caused by Coxsackie virus and is characterized by fever, sore throat and pharyngitis with discrete vesicles on the anterior pillars of the fauces, palate, uvula, tonsils and tongue. The disease is more common in summer and is usually self-limiting. Choice 1 is incorrect. Influenza will not produce the vesicular lesions described and is not more common in summer. Choice 2 is incorrect. Herpes virus may cause skin infections, aphthous stomatitis, eczema, conjunctivitis, encephalitis, cold sores, and general herpes. However, none of these conditions fit the description given for the illness in this question. Choice 3 is incorrect. Echovirus is an enterovirus which may cause meningitis, febrile illness with rash, or diarrheal disease. It is more common in the summer as is the disease caused by Coxsackie virus. However, it does not cause an illness with the symptoms described in the question. So the correct answer to question is choice 4.

Front 173

A virus causing recurrent herpetic lesions is never completely eliminated but assumes a state of1. latency.2. symbiosis.3. mutualism4. commensalism5. none of the above

Back 173

Latency. Varicella, or chicken pox, and zoster, or shingles, are both caused by the same herpes virus. The virus may infect an individual, cause varicella, and then become latent in neurons of sensory ganglia. At a later time, it may reactivate, often when the patient is under physical or emotional stress or is immunocompromised. This form of the disease will be called zoster. Choices 2, 3 and 4 are ecological terms. Symbiosis refers to a close food relationship or other working relationship between species. Among the symbiotic relationships are mutualism, choice 3, a symbiotic relationship where both species benefit; and commensalism, choice 4, a symbiotic relationship where one species benefits while the other is not affected either positively or negatively. None of the choices 2, 3 or 4 refers to recurrent herpetic lesions caused by latent herpes virus. So the correct answer to question is choice 1

Front 174

A woman just received a kidney transplant and pathological effect on the body would be is currently taking a medication to prevent organ rejection. What is the most likely mechanism of action for this medication?A. Increases blood flow to the kidneyB. Increases the number of antibodies in the bloodC. Inhibits the blood from clottingD. Prevention of inflammation in the kidneyE. Reversible inhibition of helper T lymphocytes

Back 174

The correct answer is E. Reverisible inhibition of helper T lymphocyes. When an individual receives an organ transplant the body will most likely perceive this organ as being foreign (as an antigen). Since antigenic "substances" in body will be attacked by the immune system, certain portions of the immune system must be inhibited to prevent organ rejection. Cyclosporine is an immunosuppressant agent primarily used to prevent organ rejection in patients who have received a kidney transplant. The mechanism of action for this immunosuppressant agent is related to its ability to reversibly inhibit the action of helper T lymphocytes. By reversibly inhibiting the helper T lymphocytes, the entire immune system will not be able to elicit an immune response against the "foreign" organ. Adequate blood flow to the kidneys is necessary; however, increasing blood flow to the kidneys (choice A) will not prevent an immune response. Increasing the number of antibodies in the blood (choice B) will promote organ rejection. Inhibiting the blood from clotting (choice C) and preventing inflammation in the kidney (choice D) are necessary; however, these factors will not prevent an immune response.

Front 175

Addison's Disease, a disorder of adrenal insufficiency, can lead to the development of oral lesions in any area of the mouth; however, these oral lesions are most commonly found on theA. Buccal mucosaB. Dorsum of the tongueC. Gingival marginD. Soft palateE. This disease is not associated with the development of oral lesions

Back 175

The correct answer is A. Buccal mucosa Addison's disease is a condition caused primarily by inadequate glucocorticoid production. This disorder is primarily caused by a destruction of the zona fasciculata by an autoimmune response of the body. This disorder primarily produces oral lesions on the buccal mucosa, although these lesions can appear anywhere in the mouth. The lesions are typically blotches or spots of bluish-black to dark brown pigmentation. Furthermore, there is a diffuse pigmentation of the skin around the lesions. In addition to these oral lesions, individuals will normally experience a dramatic decrease in blood glucose levels several hours after a meal. In other words, individuals with this disorder may experience hypoglycemia. In this disorder, there usually are elevated ACTH levels. Furthermore, one would typically expect to see hyponatremia and excessive water loss. One of the classic characteristics of Addison's disease is that patients often present with chronic weakness secondary to a continual weight loss

Front 176

Adenocarcinomas of the large intestine are most common in which segment?1. Ascending colon2. Transverse colon3. Descending colon4. Rectosigmoid colon

Back 176

The correct answer is choice 4. Rectosigmoid Colon. Adenocarcinomas of the colon or large intestine constitute approximately 98% of all colonic cancers. They are environmentally linked and are associated with dietary factors including possibly low fiber diets or excess meat and fat intake. They are also associated with villous adenomas such as ulcerative colitis, Crohn's disease, Gardiner's syndrome and familial polyposis. They can spread by extension or metastasis. Approximately 75% occur in the rectum or sigmoid colon. So the correct answer to question is choice 4.

Front 177

Administration of tetanus toxoid provides what type of immunity?A. InnateB. Natural activeC. Natural passiveD. Artificial activeE. Artificial passive

Back 177

The correct answer is choice D. Artificial active. Tetanus toxoid is a form of tetanus toxin damaged by heat or formalin, so that it is not dangerous, but is still immunogenic. It can be administered to the patient, who then develops anti-toxin antibodies. Since the patient develops his/her own antibodies, it is active. Since the antibodies are produced against a manufactured substance,(such as a toxoid or a vaccine) and not the organism itself, it is artificial. In passive immunity, antibodies are formed in another person or organism, and transferred to the affected individual. An example of natural, passive, is antibodies transferred from mother to child across the placenta. An example of artificial passive is tetanus antitoxin, antibodies formed by other individuals, transferred to a person following tetanus exposure. Note that teteanus toxoid and tetanus antitoxin are two different substances, the first causing antibody production, and the second giving passive immunity from disease. So the correct answer to question is choice D

Front 178

Aflatoxin is produced byA. Mucor.B. Candida.C. TricophytonD. PenicilliumE. Aspergillus

Back 178

The correct answer is choice E. Aflatoxin is produced by Aspergillus. Aspegillosis is a disease arising from several species of ubiquitous molds. Organisms are normal inhabitants of the soil, and spores are readily disseminated into the air. Choice A - Mucor does not produce Aflatoxin and is most often caused by the organisms Rhizopus and Mucor. These molds are ubiquitous on decaying vegetable matter in soil. Choice B - Candida does not produce Aflatoxin , and is a normal inhabitant of mucocutaneous body surfaces, soil, hospital environments and some foods. Choice C - Tricophyton does not produce Aflatoxin and is a mycotic infection of any keratinous structure of the skin and its appendages. Choice D - Penicillium does not produce Aflatoxin and is the source of penicillin. Therefore the correct answer to question is E

Front 179

After a hamstring injury, an individual has difficulty flexing and medially rotating her thigh. What muscles of the hamstring group did this individual most likely injure?A. Biceps femorisB. Rectus femorisC. SatoriusD. SemimembranosusE. Vastus intermedius

Back 179

The correct answer is D. Semimembranosus. This pathophysiology "type" question is basically asking "What muscle is responsible for flexing and medially rotating the thigh?" The semimembranosus muscle has this function. Note that the semitendinosus muscle also has this same action. The biceps femoris (choice A) flexes, extends and adducts the thigh. The rectus femoris (choice B) extends the leg and flexes the thigh. The satorius (choice C) flexes the leg as well as flexes and laterally rotates the thigh. The vastus intermedius (choice E) is responsible for extending the leg.

Front 180

All of the following are associated with Cushing syndrome EXCEPT:A. abnormal fat depositionB. "moon face"C. hypotensionD. diabetesE. muscle wasting

Back 180

The correct answer is choice C. Hypotension. Cushing syndrome symptoms are based primarily on the effects of excess cortisol and sometimes on associated excess aldosterone. Abnormal deposition of fat (choice A) causes an unusual physical appearance, including both "moon face" (choice B) and "buffalo hump." Also, the patient often becomes obese. Diabetes (choice D) results from the glucose-raising effects of cortisol in about 20-30% of cases. Also common are weakness, fatigue, and susceptibility to infection (choice E). Hypertension (not hypotension) is also common and is believed to be related to aldosterone increases, which often accompany the cortisol increases

Front 181

All of the following are associated with primary aldosteronism EXCEPT:A. hypernatremiaB. hyperkalemiaC. hypertensionD. polyuriaE. polydipsia

Back 181

The correct answer is choice B.hyperkalemia Much of the answer can be reasoned from the standard effect of aldosterone, which causes the nephron to resorb more sodium and excrete a watery hypotonic urine. Excess sodium retention causes hypernatremia (excess sodium levels) (choice A) in tissue. The excretion of large volumes of water is polyuria (choice D), and to make up for the fluid loss, large amounts of water are taken in (polydipsia) (choice E). Note that in normal kidney physiology, retention of sodium is accompanied by loss of potassium. The excess loss of potassium results in a condition known as hypokalemia (low potassium), not hyperkalemia (high potassium).

Front 182

All of the following are characteristic of the stools seen in patients with Giardia infections EXCEPTA. Blood is presentB. Mucus is not presentC. The diarrhea is malodorousD. They are greasy and tend to floatE. The diarrhea caused can be acute or chronic in nature

Back 182

The correct answer is A. Blood is present. Giardiasis is a protozoal infection of the upper small intestine caused by Giardia lamblia. Persons of all ages can be affected by this organism; however, the incidence is highest in children. A large percentage of individuals infected with this organism are asymptomatic. However, those who are symptomatic for diarrhea typically present with the following characteristic stools: The stools are typically free of blood and mucus (choice B). The stool is often very malodorous (choice C), greasy, tends to float (choice D) and is often bulky in nature. Depending on the severity of the infection, the diarrhea caused can be acute or chronic in nature (choice E)

Front 183

All of the following are true concerning "fibroid tumors" of the uterus EXCEPT:A. malignant transformation is rareB. they may require removal due to bleeding tendencyC. they are also known as leiomyosarcomasD. they are composed of smooth muscleE. they are the most common tumor in women

Back 183

The correct answer is choice C.. they are also known as leiomyosarcomas FALSE! Fibroids are benign smooth muscle tumors (choice D) and are the most common neoplasm in women (choice E). They rarely undergo malignant transformatron (choice A) but are often removed surgically due to effects on fertility and increased bleeding (choice B). They are actually leiomyomas (benign) and not leiomyosarcomas (rare malignant neoplasms). Symptoms may include uterine bleeding, abnormal menstrual bleeding, infertility, pain, or urinary symptoms

Front 184

All of the following are true concerning carcinoma of the prostate EXCEPT:A. it is the most common cancer in American malesB. it is usually an adenocarcinomaC. symptoms may mimic those of BPHD. it can be detected by digital rectal examE. it can be detected through specific antigen

Back 184

The correct answer is choice A. Prostate cancer is the second most common cancer in men (lung cancer is first). It is usually an adenocarcinoma (choice B). Like benign prostatic hypertrophy (BPH), it often shows first as difficulty in urination, has a fairly high incidence in men over 50, and incidence increases with age (choice C). Survival was formerly significantly less than now due to late discovery with symptoms or rectal exam (choice D). The use of PSA tests (prostate specific antigen) (choice E) for screening of men over 50 has resulted in more early detection and treatment. The use of radioactive seeds has joined surgical removal and beam radiation as a standard treatment.

Front 185

All of the following are true concerning mesothelioma EXCEPT:A. it is related to asbestos exposureB. asbestos and smoking are synergistic causesC. it has an extremely long latent periodD. it is not a bronchogenic tumorE. it has a poor prognosis

Back 185

The correct answer is choice B. Surprisingly, smoking does not act synergistically with asbestos in causing mesothelioma. These two factors are synergistic in causing bronchogenic tumors (choice D). Mesothelioma is not a bronchogenic tumor, but instead is a tumor of the pleura of the lung. The classic case of mesothelioma involves asbestos exposure (choice A), usually occupational, followed by an extremely long latent period of 25-40 years (choice C) before symptoms of the tumor develop. Mesothelioma generally has a very poor prognosis (choice E).

Front 186

All of the following are typical inhabitants of damaged tissue in Vincent's stomatitis EXCEPT:A. PeptostreptococcusB. StreptococcusC. BacteroidesD. FusobacteriaE. Borrelia

Back 186

The correct answer is choice B. Streptococci are Gram-positive facultative anaerobes. They are common inhabitants of both the soft tissues and hard tissues of the mouth. They are not found, however, to a great degree in lesions of Vincent's stomatitis (acute necrotizing ulcerative gingivitis (ANUG, trenchmouth). The flora found in this disease are primarily anaerobic and include spirochetes, Borelia (choice A), Bacteroides (choice C), Fusobacteria (choice D), and Peptostreptococcus (choice E

Front 187

Allergens that are usually responsible for contact hypersensitivity are1. lipids.2. haptens3. proteins4. carbohydrates

Back 187

The correct choice is choice 2, haptens. Contact hypersensitivity occurs when an individual who has been previously exposed to an allergen comes in contact with the allergen. During the prior exposure, mast cells became coated with IgE molecules. On repeat exposure, the allergen cross-links the IgE molecules and mast cell degranulation ensues. This causes edema, inflammation and erythema at the site. Eosinophils are attracted which serve to attenuate the inflammatory response. The allergens which cause contact hypersensitivity can be lipid (choice l), protein (choice 3), or carbohydrate (choice 4). Regardless of their composition, they are referred to as haptens. Haptens are molecules which cannot induce antibody production unless they are complexed to a large protein. Haptens are capable of cross-linking antibodies on their own, however, as long as those antibodies have been previously produced. Thus, haptens can initiate the hypersensitivity response. Once again, the correct choice to question is choice 2

Front 188

Amyloidosis is characterized by all of the following EXCEPT:A. cells notable for basophilic stain reactionB. proteinuriaC. glomerular damageD. hepatomegalyE. cardiac arrhythmias

Back 188

The correct answer is choice A. cells notable for basophilic stain reaction False!Amyloidosis involves deposition of highly specialized proteins in various organs. The proteins include an immunoglobulin-like AL (amyloid light chain) and a unique nonimmunologic AA (amyloid-associated protein), as well as a glycoprotein P component. Deposition in the kidney causes glomerular damage (choice C) and proteinuria (choice B). Deposition in the spleen and liver cause hepatosplenomegaly (choice D). Damage to the heart may involve cardiomyopathy, arrhythmia, or heart failure (choice E). Amyloid proteins are notable for a strong reaction to the eosin part of H and E stain, making the amyloid deposits highly eosinophilic (not basophilic

Front 189

An autosomal dominant trait showing 50 percent penetrance will be phenotypically expressed in what percent of the offspring?A. 0B. 25C. 33D. 50E. 75

Back 189

The correct answer is choice B. 25% Penetrance refers to the extent to which a given gene expresses itself. To illustrate, imagine a dominant gene for green hair, G. Both genotypes GG and Gg are expected to phenotypically have green hair. However, due to environmental factors, or due to the effect of other related genes, green hair may not always show phenotypically, even though the individual posseses the dominant G gene. If it actually shows in the appearance of 50% of the individuals who have the appropriate genotype, it is said to have 50% penetrance. The rest of the problem is math. If, for some reason, male parents in a large group express this green trait 50% of the time and female parents also express this green trait 50% of the time, we expect the offspring to express it 50% times 50% or 25% of the time. So the correct answer to question is choice B

Front 190

An embolus originating as a thrombus in the femoral vein usually occludes a blood vessel in the1. lung.2. brain.3. liver.4. kidney

Back 190

The correct answer is choice 1.LUNG The key here is to trace the path of a thrombus through the vascular system. If the thrombus or clot forms in the femoral vein, it will eventually continue to travel back in the venous system until it reaches the vena cava. It is thus entering larger and larger veins. It will then pass through the right atrium, right ventricle and into the pulmonary artery. The pulmonary artery will branch into smaller arteries and eventually capillaries in the lung. Somewhere along the way the thrombus will get caught in one of the small arteries or arterioles of the lung. So choice 1 is correct. Choices 2, 3 and 4 are all incorrect because the blood will pass through the lung and back again to the left side of the heart before it could reach the brain, liver or kidney. So again, the correct answer to question is choice 1

Front 191

An increased serum acid phosphatase level is clinically significant and aids in the diagnosis of which of the following conditions?1. Paget's disease of bone2. Primary hyperparathyroidism3. Secondary hyperparathyroidism4. Breast carcinoma with bone metastasis5. Prostatic carcinoma with bone metastasis

Back 191

All five conditions listed involve bone pathology. However, elevated acid phosphatase will help distinguish prostatic metastatic carcinoma from the others. Acid phosphatase is produced by prostatic epithelium and is elevated in later, but not early, prostatic carcinoma. Choice 1 is incorrect. Paget's disease or osteitis deformans involves bone resorption and replacement with poorly mineralized tissue. In this disease, alkaline phosphatase, not acid phosphatase, is highly elevated. Choices 2 and 3 are incorrect. Primary hyperparathyroidism involves adenoma, hyperplasia or carcinoma of the parathyroid gland and is accompanied by elevated serum calcium and elevated parathyroid hormone. Secondary parathyroidism is often caused by chronic renal failure and vitamin D deficiency. It may be accompanied by lower serum calcium. Breast carcinoma with bone metastasis is not accompanied by elevated acid phosphatase. So the correct answer to question is choice 5

Front 192

An individual that presents with keratoconjunctivitis, parotid gland enlargement and a positive Rh factor is most likely to be diagnosed withA. Polyarteritis nodosaB. Reiter's syndromeC. Rheumatoid arthritisD. Sjögren's syndromeE. Systemic Lupus Erythematosus

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The correct answer is D. Sjögren's syndrome is an autoimmune disorder that is characterized by a chronic dysfunction of exocrine glands. Individuals with this disorder often present with keratoconjunctivitis, parotid gland enlargement, dry mouth leading to a difficulty speaking and swallowing, loss of taste, and pleuritis. A positive Rheumatoid factor (Rh factor) is seen in over 70% of all patients with this disorder. Polyarteritis nodosa (choice A) is a disorder characterized by focal or segmental lesions of blood vessels. The pathological hallmark of this disease is acute necrotizing inflammation of the arterial media with extensive inflammatory cell infiltration of all layers of the vessels and surrounding tissue. Patients also present with fever, hypertension, abdominal pain, and elevated sedimentation rate. Reiter's syndrome (choice B) is the leading cause of arthritis in young adults, especially men. This disorder is commonly associated with a recent onset of arthritis, conjunctivitis and urethritis. Another common finding in this condition is keratoderma blennorrhagicum, which typically presents as an erythematous pustular, scaly and plaque-like set of lesions on the palms of the hands and soles of the feet. Rheumatoid arthritis (choice C) is a progressive disorder of unknown etiology. The characteristic feature of this disorder is the persistent inflammatory synovitis, usually involving the peripheral joints in a symmetric manner. Although a positive Rh factor is seen many individuals with the disorder, keratoconjunctivitis and parotid gland enlargement are not commonly seen. Systemic lupus erythematosus (choice E) is associated with arthralgias, fatigue, malaise, fever, and weight loss as well as the malar "butterfly" rash. This is an erythematous rash raised over the cheeks and bridge of the nose. Various renal and nervous system complications are also associated with this disorder.

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An individual with Addison's disease is most likely to experience which of the following?A. Decreased ACTH levelsB. HypernatremiaC. HypoglycemiaD. Water retentionE. Weight gain

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The correct answer is C. Hypoglycemia. The symptoms of this disorder are primarily due to the destruction of the zona fasciculata by an autoimmune response of the body. In Addison's disease, individuals will normally experience a dramatic decrease in blood glucose levels several hours after a meal. In other words, individuals with this disorder may experience hypoglycemia. In this disorder, there are normally elevated ACTH levels (choice A). Furthermore, one would typically expect to see hyponatremia (choice B) and excessive water loss (choice D). One of the classic characteristics of Addison's disease is that patients often present with chronic weakness secondary to a continual weight loss (choice E).

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An individual with mitral regurgitation will most likely suffer from which of the following?A. Decreased heart rateB. Fluid congestion in the lungsC. Increased cardiac output from the ventriclesD. Peripheral edemaE. Ventricular arrhythmias

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The correct answer is B. Fluid congestion in the lungs. Mitral regurgitation is a clinical condition that occurs when the mitral valve leaflets are not able to close normally resulting in the "left ventricular" blood being ejected into the left atrium as well as through the aortic valve with each ventricular contraction. The net effect is an increased volume load on the left ventricle and an increased left atrial pressure. When the pressure in the left atrium increases, pulmonary edema will begin. As the amount of fluid in the lungs increases, the patient will begin to experience increasing dyspnea and fatigue. In mitral regurgitation, the heart rate (choice A) will either remain constant or slightly elevated in an effort to compensate for the extra "load" on the left ventricle. Since the net effect of mitral regurgitation is an increased volume load on the left ventricle and an increased left atrial pressure, cardiac output from the ventricles decreases (choice C). Peripheral edema (choice D) typically occurs when there is some degree of "right sided" heart problem. When the mitral regurgitation is chronic in nature, the patient is more likely to develop atrial arrhythmias, not ventricular arrhythmias (choice E).

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An oral lesion that may appear as an ulcer, a nodule or a vegetative process and is often mistaken for squamous cell carcinoma is a manifestation of1. candidiasis.2. trichinosis.3. sporotrichosis.4. histoplasmosis

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The correct answer is choice 4. Histoplasmosis is a fungal disease caused by Histoplasma capsulatum. Infection occurs via the respiratory system and is often asymptomatic. In severe disseminated cases, ulcers of the nose, mouth, tongue and intestine can occur. The ulcers contain focal areas of necrosis in small granulomas. These ulcers may be confused with ulcerous areas of carcinomas. Choice 1 is incorrect. The lesions in candidiasis or thrush, another fungal infection, are whitish plaque-like areas. Choice 2 is incorrect. Trichinosis, a disease caused by flatworms, does not usually produce oral lesions. Choice 3 is incorrect. Sporotrichosis is a fungal disease usually traumatically introduced into the skin. The lesion is usually localized in the area of introduction and does not spread to the oral tissues. So the correct answer to question is choice 4

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An Rh-negative mother delivered a normal first child. Her second child developed symptoms of erythroblastosis fetalis. Which of the following can be concluded?1. The father is Rh-negative.2. The first baby is Rh-negative.3. The first baby is a girl; the second is a boy.4. The mother has very high levels of serum complement and anti-Rh IgE.5. None of the above

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The correct answer is choice 5. NONE OF THE ABOVE. Erythroblastosis can occur when Rh negative mothers are carrying Rh positive fetuses; in particular, second Rh positive fetuses. The situation can only occur when the fetus is Rh positive due to the fact that the father is Rh positive. So choice 1 is incorrect. Choice 2 is also incorrect. Both children must be Rh positive as the first Rh positive baby sensitizes the mother's immune system to form anti-Rh antibodies and the second child causes a full and rapid antibody response. Choice 3 is incorrect as the sex of either the first or second child is irrelevant to this condition. Choice 4 is incorrect. Anti-Rh immunoglobulin would not be IgE because IgE is involved primarily in allergic reactions of skin and other tissues and binds to mast cells and basophils. It would not form as an anti-Rh antibody. So the correct answer to question is choice 5

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Anemia found in iron deficiency is of which type?A. MacrocyticB. MicrocyticC. NormocyticD. Hyperchromic

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The correct answer is choice B. MICROCYTIC. Macrocytic (choice A) refers to larger than normal cells, normocytic (choice C) to normal size cells, and microcytic to undersized cells. Hyperchromic (choice D) is more colored than normal, normochromic is normal color, and hypochromic is less colored. The anemia in iron deficiency causes an inability to produce hemoglobin, and the resultant erythrocytes are smaller and less red than normal (microcytic, hypochromic). In pernicious anemia, they are macrocytic and are accompanied by hypersegmented neutrophils. In blood loss, cells are initially normocytic and normochromic but become macrocytic as the marrow falls behind in RBC replacement

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Anthrax is caused by bacteria of the genus:A. NeisseriaB. ClostridiumC. BacillusD. CorynebacteriaE. Mycobacteria

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The correct answer is choice C. Anthrax is caused by Bacillus anthracis, a Gram-positive, spore-forming rod. B. anthracis is the major pathogen of the genus. Other Bacillus species include B. cereus and B. subtilis, which are soil organisms. B. cereus may sometimes grow on food and give off an exotoxin, causing a form of food poisoning. B. stearothermophilus should be familiar as the "spore test" or biologic monitor for autoclaves.

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Antiseptics differ from disinfectants in that antiseptics1. sterilize.2. kill pathogens.3. are bacteriostatic only.4. are applied to viable tissues

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The correct choice is choice 4. Antiseptics are chemical agents which are applied to tissues to inhibit the growth of pathogenic bacteria or to kill pathogenic bacteria. Examples of antiseptics include betadine, alcohol and various soaps. Disinfectants are also chemical agents, but they are generally more caustic than antiseptics. They kill cells indiscriminstely and may cause severe damage to viable tissues. Examples of disinfectants include alkylating agents, oxidants and sulfhydryl reagents. Choice 1 is incorrect because antiseptics and disinfectants do not sterilize tissues or surfaces. Sterilization occurs when all microorganisms are destroyed. Antiseptics and disinfectants reduce the infectivity of matter, but nonpathogenic organisms may remain viable. Choice 2 is incorrect because antiseptics are less bacteriocidal than disinfectants. In fact, disinfectants are defined as those agents which are bacteriocidal at low concentrations. The bacteriocidal properties of antiseptics make choice 3 incorrect. Antiseptics are bacteriostatic, but they are not exclusively bacteriostatic. They can be bacteriocidal as well. Once again, the correct choice for question is choice 4.

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As a result of dental prophylaxis, microorganisms around teeth enter the bloodstream. This condition is an example of1. pyemia.2. toxemia.3. bacteremia.4. septicemia.5. focal infection

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The correct choice is choice 3, bacteremia. Bacteremia literally means bacteria in the blood stream. It can be caused by a variety of conditions. Bacteremia occurs, for example, when pneumococcal pneumonia leads to pneumococcal meningitis. Here, some bacteria from the lung enter the blood stream, causing bacteremia. The organisms are canied by the blood to the meninges where they cause a severe infection. Bacteremia also occurs following dental procedures, including routine cleaning. Patients with valvular heart disease are encouraged to take prophylactic antibiotics prior to dental procedures to protect their valves from the bacteremia induced by the dentist. In septicemia, choice 4, organisms can also be cultured from the blood stream. Septicemia differs from bacteremia in that the former is associated with hypotension, increased cardiac output and decreased peripheral resistance. Septicemia is a life-threatening condition and requires IV antibiotics immediately. Bacteremia rarely requires treatment. Pyemia, choice 1, literally means pus in the blood. Pyemia is usually associated with septicemia or bacteremia. It rarely occurs in sterile blood. Toxemia, choice 2, occurs when a poison circulates in the blood. Examples of toxemia include botulism in which botulism toxins circulate or the toxic shock syndrome in which toxins produced by Staphylococci circulate. Focal infection, choice 5, is a condition wherein bacteria can be isolated from only one site. Once bacteria enter the blood stream, the infection becomes diffuse. Once again, the correct choice to question is choice

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Bacille Calmette Guerin (BCG) is best described as a(n):A. antibioticB. vaccineC. antitoxinD. tuberculin testE. passive immunity

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The correct answer is choice B. VACCINE BCG is also known as Bacille Calmette Guerin, and is an attenuated-related mycobacterium. It has been given to many tuberculin-negative individuals around the world and results in a variable resistance to tuberculosis (TB). People vaccinated with BCG develop antibodies that are sometimes effective against TB. Therefore, BCG is best described as a vaccine. Since the patient forms his/her own antibodies, it is active, not passive, immunity (choice E). It is not an antibiotic (choice A), as it does not kill bacteria. It is not an antitoxin (choice C), as it does not counteract a toxin formed by mycobacteria. It is not the tuberculin test (choice C), which is accomplished using PPD (purified protein derivative) derived from mycobacterial cells

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Bacteremias in patients with heart valve abnormalities may result in1. scarlet fever.2. rheumatic fever.3. Ludwig's angina.4. infective endocarditis.5. streptococcal pharyngitis

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The correct answer is choice 4. Infective endocarditis is a bacterial infection of the lining tissues of the heart including the heart valves. It is caused by Streptococci or Pneumococci. Valves with irregularities of structure or function are more susceptible to being colonized by bacteria which sometimes enter the bloodstream. A large group of bacteria traveling in the bloodstream is known as a bacterernia and a hacterernia can be caused by dental treatment including prophylaxis. scaling and root planning. This fact leads to the necessity for antibiotic prophylaxis for dental patients with heart valve abnormalities. Choice 1 is incorrect. Scarlet fever is an infection caused by group A beta hemolytic Streptococci. Choice 2 is also incorrect. Rheumatic fever is a disease also caused by hcrnolytic Streptococci. It can lead to heart valve damage which later can make a patient more susceptible to endocarditis. Choice 3 is incorrect. Ludwig's angina is a massive inflammation and cellulitis especially of the mandibular and pharyngeal areas which can lead to blockage of the air passages. It is a possible sequela of Streptococcal infection, choice 5. Streptococcal pharyngitis is sore throat caused by Streptococci. So the correct answer to question is choice 4.

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Bacteria with high lipid content in their cell walls include all of the following EXCEPT:A. corynebacteriaB. mycobacteriaC. nocardiaD. bacteroides

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The correct answer is choice D. Bacteroides are a genus of Gram-negative, anaerobic bacteria, including B. fragilis, B. melaninogenicus, and B. gingivalis. B. gingivalis and B. melaninogenicus are common findings in diseased periodontal pockets. Bacteroides is not known for an especially high lipid content of the cell wall. The other bacteria listed all contain a high level of lipids in their walls. Mycobacterium (choice B) contains many waxes, fats, and mycolic acids, and this fatty wall prevents easy entrance of antibiotics into the cells. Nocardia (choice C) are closely related to Mycobacteria and share the same mycolic acid based cell wall structure. The two genera are known as the acid-fast bacteria. Corynebacteria (choice A) include C. diphtheriae, the causative agent of diphtheria. They are Gram-positive aerobes. Their cell wall is notable for having a high lipid and wax content, although they are not acid fast

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Bacterial capsules usually consist of1. chitins.2. celluloses.3. polypeptides.4. polysaccharides

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The correct answer is choice 4. polysaccharides Bacterial capsules are layers surrounding the cell wall. They are usually composed of polysaccharides, choice 4, and are rarely composed of polypeptides, choice 3. So in terms of the most usual structure, the correct answer is choice 4. The bacterial cell wall varies in structure in various types of bacteria but may contain polypeptides, lipoproteins, polysaccharides and other materials. Choice 1 is incorrect. Chitins are found in cell walls of fungi and in exoskeletons of insects. Choice 2 is incorrect. Celluloses are primarily found in plant cell walls and some related polysaccharides as mentioned are found in bacterial cell walls. So the correct answer to question is choice 4.

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Bacterial endotoxins may play a role in development of periodontal disease due to1. high amounts of endotoxin in plaque.2. the ability of endotoxins to incite an inflammatory response.3. the fact that endotoxins are similar to ground substance.4. the presence of endotoxins in both gram-positive and gram-negative bacteria.5. none of the above

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The correct choice is choice 2, the ability of endotoxins to incite an inflammatory response. Endotoxins are lipid moieties found in the outer membrane of gram-negative bacteria. They are not found in gram-positive organisms; therefore, choice 4 is incorrect. Endotoxins may incite local inflammatory responses, but they are generally of greater pathologic significance when circulating in the blood stream. They cause systemic effects of vasodilatation and vascular leakage which ultimately lead to shock. They also increase clotting and may induce disseminated intravascular coagulation. Their role in periodontal disease stems from their ability to activate complement and attract neutrophils and macrophages. Endotoxin is not present in high amounts in plaque as stated in choice 1. Plaque is a complex of primarily gram-positive organisms and dextran. As stated, gram-positive organisms lack endotoxin, though some gram-positive organisms are capable of causing a clinical syndrome which looks very much like endotoxic shock. Ground substance, mentioned in choice 4, is not similar to endotoxin. Ground substance is the intracellular cement made up of hyaluronic acid and other mucopolysaccharides. Endotoxin is composed of lipopolysaccharide. Once again, the correct choice to question is choice 2

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Bacterial flagella are:A. similar in structure to eukaryotic flagellaB. composed of a 9+2 filament arrangementC. composed of microtubulesD. composed entirely of protein

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The correct answer is choice D. composed entirely of protein. Several differences exist between prokaryotic cells, including bacteria and eukaryotic cells. Among them is the structure of the flagellum, which is the major organ of locomotion for many bacterial species. The standard eukaryotic (advanced cell, NOT bacterial cell) flagellum consists of a microtubular structure with nine pairs of tubulin microtubules surrounding an inner core of two single microtubules. This is the familiar "9+2" arrangement. The bacterial (prokaryotic) cell does not share this structure, having only a protein-based flagellum without the 9+2 structure. Large differences also exist between eukaryotic and prokaryotic nuclei, mitochondria, and ribosomes

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Bence-Jones proteins are tumor markers for which of the following types of cancer?A. HepatocellularB. MyelomaC. OvarianD. PancreaticE. Prostate

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The correct answer is B.Myeloma. Tumor markers can be used to aid in the screening, diagnosis and monitoring of an individuals response to the treatment of the cancer. Furthermore, tumor markers can aid in the "staging" of an individuals cancer. Bence-Jones proteins can be used to diagnose and help in the prognostic indications for multiple myeloma. Hepatocellular (choice A) carcinoma can be monitored with the detection of alpha-fetoprotein. Ovarian cancer (choice C) is monitored by the presence of CA 125; a high level of this tumor marker is closely related to a poor prognosis. Pancreatic (choice D), colorectal and gastric carcinoma can be followed by the presence of CA 19-9. Prostate cancer (choice E) is monitored by the presence of PSA (prostate-specific antigen

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Beta-thalassemia results in:A. microcytic cells with excess beta hemoglobinB. microcytic cells with insufficient beta hemoglobinC. macrocytic cells with excess alpha hemoglobinD. macrocytic cells with insufficient alpha hemoglobin

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The correct answer is choice B.microcytic cells with insufficient beta hemoglobin In the thalassemias, insufficient amounts of one hemoglobin chain are produced. In beta thalassemia, insufficient beta chain is produced, resulting in a microcytic cell filled with excess alpha chain. The alpha chains can aggregate, become insoluble, and lead to hemolysis and anemia. Patients homozygous for this disease or who are transfusion-dependent are known as B-thal major

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Biological monitors, used for autoclave testing, are composed of:A. Viral sporesB. Mycobacterium tuberculosisC. Live bacteriaD. Bacterial sporesE. A combination of viruses, fungi and bacteria

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The correct answer is choice D. BACTERIAL Spores, such as those of Bacillus stearothermophilus, are especially heat tolerant. If they are killed by some sterilizing process, then you can be sure that all other microorganisms are killed as well. These spores are sometimes referred to as "benchmark" organisms for sterilization. Because of this property, we do not need to test our autoclave with a combination of different organisms. Note that there are no viral spores. Note also that Mycobacterium tuberculosis is the "benchmark" organism for surface disinfectants

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Blood in the sputum is characteristic of each of the following EXCEPT one. Which one is this EXCEPTION?A. EmphysemaB. TuberculosisC. Lobar pneumoniaD. Pulmonary embolismE. Bronchogenic carcinoma

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The correct answer is choice A. Emphysema In each case we will try to figure a source for blood in the sputum. In the case of tuberculosis, there is an active infection by Mycobacterium tuberculosis with accompanying fever, anorexia, necrosis of lung tissue and destruction of blood vessels in lung parenchyma. Similarly, in lobar pneumonia, an infection is present which can erode surrounding blood vessels. In a pulmonary embolism, a thrombus, most likely from a leg vein, becomes lodged in the lung. If the embolus becomes infected (septic embolus), then the situation is similar to that just mentioned. A bronchogenic carcinoma can cause bleeding as it expands into nearby vascular tissue. Emphysema is usually not accompanied by bleeding. There is collapse of alveolar walls with loss of diffusional surface area, cough, dyspnea and barreled chest. So the correct answer to question is choice A

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Both heat and alcohol damage bacteria primarily by:A. denaturing proteinB. alkylating DNAC. oxidizing sulfhydryl groupsD. dissolving fatty cell membranes

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The correct answer is choice AA. denaturing protein. All of the processes listed can be used to kill or inactivate microorganisms. Alcohol and heat (dry or steam) primarily act as protein denaturants. Dry heat can kill by desiccation ethylene oxide and glutaraldehyde alkylate nucleic acids. Peroxides, chlorine, iodides, and mercury based compounds act on sulfhydryl groups. Detergents can damage fatty parts of cell membranes

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By definition, which of the following antibacterials specifically retards the growth of organisms eventually leading to the death of the organism?A. AcyclovirB. CefiximeC. ClarithromycinD. LevofloxacinE. Penicillin

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The correct answer is C.Clarithromycin This question is essentially asking, "Which of the following antibiotics are bacteriostatic?". As a general rule, all antibiotics can be classified as either a bacteriostatic or bactericidal agent. Bacteriostatic antibiotics inhibit or retard the growth of bacteria, which will eventually lead to the death of the organisms. Bactericidal antibiotics directly cause the death of bacteria. Antibiotics are generally placed in "classes" according to their mechanism of action. For example, clarithromycin (choice C), a macrolide antibiotic, is a bacteriostatic agent that binds to the 50S ribosomal subunit of susceptible organisms and inhibits RNA-dependent protein synthesis. Acyclovir (choice A) is an antiviral agent commonly used in the treatment of herpes virus infections. Cefixime (choice B) is a bactericidal cephalosporin antibiotic that interferes with bacterial cell wall synthesis. Levofloxacin (choice B) is a bactericidal Fluroquinolone antibiotic that inhibits bacterial DNA gyrase leading to the death of the organism. Penicillin (choice E) is a bactericidal penicillin antibiotic that interferes with bacterial cell wall synthesis

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Cervicofacial actinomycosis is usually due to1. poor aseptic technique during oral surgery.2. contamination of a trauma or surgical site with spores.3. contamination of a trauma or surgical site with endogenous organisms.4. spread of the organisms from a dermal or thoracic infection

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The correct answer is Choice 3.contamination of a trauma or surgical site with endogenous organisms. Actinomycosis is a chronic suppurative disease that forms draining sinus tracts and is caused by Actinomyces israelii and related filamentous bacteria. They are part of the normal flora of the oral cavity and why they begin to invade tissue is not clear. However, it is believed that trauma, such as tooth extraction, necrotizing bacterial infection or aspiration, may cause clinical actinomycosis. Typical lesions may drain to the outside through sinuses and contain so-called sulphur granules of the central mycelium and filaments. So choice 3 is correct as it involves trauma and endogenous organisms or normal flora. Choice 2 is incorrect as Actinomyces does not form spores. Choice 1 is incorrect as the source of Actinomyces is the endogenous flora and not bacteria that might be present from outside sources and spread through aseptic technique. Choice 4 is incorrect. Although infections may often drain to the face, the source of the bacteria is the oral cavity and not the skin of the face or thorax. So the correct answer to question is choice 3.

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Chronic passive congestion of the lung is characterized by1. hyaline membranes.2. chronic bronchitis.3. giant cell arteritis.4. interstitial infiltration of PMN's.5. edema of alveolar walls and "heart failure" cells

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The correct answer is choice 5. edema of alveolar walls and "heart failure" cellsPulmonary congestion involves elevated hydrostatic or lowered colloidal blood pressure, increased capillary permeability, decreased lymphocytic drainage, edema, and increased sodium retention. It is often associated with heart failure or shock. Hemosiderin-filled macrophages are often found in alveolar spaces and are the so-called heart failure cells. Choice 1, hyaline membranes, are often associated with viral or mycoplasmal pneumonia, but not chronic passive congestion. Choice 2, chronic bronchitis, is a chronic obstructive disease and may lead to pulmonary emphysema and other pulmonary problems, but not chronic passive congestion. Choice 3, giant cell arteritis, is a granulomatous inflammation of small- and medium-sized vessels, especially cranial vessels. Choice 4 is incorrect. Interstitial infiltration of PMNs occurs often with bacterial pneumonia, but not with chronic passive congestion. So the correct answer to question is choice 5

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Classic hemophilia is due to a deficiency of normal Factor VIII which in turn is due to a genetic deficiency that is1. partially dominant.2. autosomal dominant.3. autosomal recessive.4. sex-linked dominant.5. sex-linked recessive

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The correct answer is choice 5. sex-linked recessive Hemophilia A or classic hemophilia is a deficiency of Factor VIII-C, leading to a secondary hemostasis deficit. Factor VIII-C is a clotting protein and, in classic hemophilia, it can either not be produced from its precursor or, a when produced, it is defective. Hemophilia A is inherited as a sex-linked recessive trait; that is, it is carried on the X chromosome and transmitted primarily from carrier heterozygous mothers to sons. So the correct answer to question is choice 5

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Corynebacterium diptheriae is often associated with tonsillopharyngeal infections; this bacteria can be best classified as a(n)A. anaerobic bacteriaB. gram negative rodC. gram positive cocciD. gram positive rodE. virus

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Corynebacterium diptheriae is an aerobic, nonmotile, non-sporulating, irregularly staining gram-positive rod. Infections of the respiratory tract are most often tonsillopharyngeal and may also be laryngeal and nasal. In tonsillopharyngeal infections, this bacteria may initially lead to erythema. However, spots of gray or white exudate are common. Furthermore, these "spots" often extend and coalesce within a day to form confluent sharply demarcated pseudomembranous lesions.

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Crohn disease most commonly involves the:A. duodenum and jejunumB. jejunum and ileumC. ileum and colonD. colon and rectum

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The correct answer is choice C. ILEUM AND COLON. Crohn disease is a recurrent granulomatous inflammatory disease of the bowel, most commonly affecting the terminal ileum and colon. The etiology is not clear, and infection, autoimmune, nutritional, and hormonal theories have all been considered. It has a remitting/relapsing course and is associated with a higher than normal risk of small intestine adenocarcinoma. It is more common in people of Jewish ancestry and usually begins in early adulthood. Pathologically, skip lesions are seen-areas of involvement alternating with segments of normal tissue

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Detergents kill bacteria by interfering with the function of the cell1. wall.2. capsule.3. membrane.4. ribosome.5. chromosome

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The correct answer is choice 3.membrane This is a basic cell organelle structure and property question. Detergents have the property of emulsifying and dissolving fats and lipids. Therefore, they will kill bacteria by dissolving any organelles which contain significant amounts of lipid. So cell membrane, choice 3, is correct. The cell membrane is primarily lipid and phospholipid, with a smaller amount of protein. Choice 1 is incorrect. Bacterial cell walls are composed of lipopolysaccharide, peptidoglycan or lipoprotein, but not lipid. Choice 2 is incorrect. Bacterial capsules are composed of extracellular polymers and it is almost always a polysaccharide type substance. Choice 4 is incorrect. Cell ribosomes are composed of RNA. Choice 5 is incorrect. Chromosomes are composed of DNA. So the correct answer to question is choice 3.

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Development of pseudomembranous colitis is a major adverse effect of prolonged therapy with1. vancomycin.2. clindamycin.3. tetracycline.4. streptomycin.5. cephalosporin.

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The correct choice is choice 2, clindamycin. Pseudomembranous colitis is caused by a toxin secreted by Clostridium difficile. The disease presents as watery diarrhea, but dysentery or bloody diarrhea occurs in a small percentage. On sigmoidoscopy, yellow plaques are found lining the colon. Histologically, a pseudomembrane consisting of acute inflammatory cells and fibrin can be identified. Many antibiotics can cause this disorder, but it is especially common following prolonged clindamycin treatment which upsets the normal colonic flora. Vancomycin, choice 1, is in fact the treatment, not the cause, of pseudomembranous colitis. It must be given orally to be efficacious. The major side effects of vancomycin include renal failure and deafness. Tetracycline, choice 3, has adverse effects including hepatotoxicity and photosensitivity. It rarely causes pseudomembranous colitis. Streptomycin, choice 4, is an aminoglycoside. Like all aminoglycoside, it almost never causes pseudomembranous colitis. It can, however, produce pancytopenia and anaphylaxis. The cephalosporins, choice 5, can cause anaphylaxis in penicillin-sensitive patients. In addition, these drugs may be associated with hemolytic anemias and elevations of liver enzymes. Pseudomembranous colitis is rare with these agents. Once again, the correct choice to question is choice 2

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Difficulties in controlling mycobacterial growth with antibiotics are due to all of the following EXCEPT:A. mycolic acid is present in cell wallsB. mycobacteria are quick growing and dividingC. mycobacteria are intracellular parasitesD. mycobacteria may be found in Ghon complexes

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The correct answer is choice B. Mycobacteria are notoriously difficult to kill with antibiotics. They possess waxy, fatty cell walls containing mycolic acids. These walls prevent easy uptake of antibiotics into the cell. Furthermore, the cells are often clustered in Ghon complexes of live and dead mycobacterial cells, leukocytes, and other inflammatory cells. It is also difficult for the antibiotics to penetrate the Ghon complex or walled-off tubercle. The bacteria also are found inside of the monocytes or giant cells that engulfed them. Antibiotics must pass into these cells to reach the mycobacteria. Mycobacteria also grow and divide extremely slowly, so antibiotics that depend on the growth and metabolism of the bacterial cells will act only very slowly. As a result, the course of therapy for tuberculosis is usually long (6 to 12 months

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Disseminated miliary tuberculosis results from spread of the tubercle bacillus by way of1. the lymphatics.2. the bloodstream.3. the air passages.4. direct extension.5. none of these

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The correct answer is choice 2. THE BLOODSTREAM Miliary tuberculosis refers to a widespread dissemination of the causative agent Mycobacterium tuberculosis to a number of organs and tissues. This is accomplished primarily through the bloodstream and leads to a high mortality rate. Of course, the most commonly involved organ in tuberculosis is the lung. However, other organs including the urinary tract and meninges are often infected. Likewise, tuberculosis can spread through the lymphatics or by direct extension from one organ to an adjacent organ. However, miliary or widespread tuberculosis is caused by spread through the circulatory system. So the correct answer to question 22 is choice 2.

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Dry heat destroys organisms primarily by:A. LysisB. OxidationC. Precipitation of saltsD. Dissolving of cell membranesE. Denaturation of proteins

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The correct answer is choice E. The two major effects of dry heat on microorganisms are denaturation of proteins and dehydration. Proteins lose their normal configuration and shape after a certain temperature. In the case of enzymes, these proteins are no longer functional and the organism will die. Dehydration removes all water, which is necessary for cellular life. Lysis is a general term for disruption of a cell membrane and leakage of cell contents. Detergents may dissolve the fatty part of membranes, causing lysis. Many disinfectants, such as glutaraldehyde and ethylene oxide, act by alkylation of DNA molecules. Some disinfectants, such as iodine compounds and peroxide act by oxidation of protein sulfhydryl groups.

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Each of the following characterizes a chlamydial infection EXCEPT one. Which one is this EXCEPTION?A. Large numbers of asymptomatic carriersB. Frequent co-infection with gonorrheaC. The ability of the organism to survive in the host extracellularlyD. The greater likelihood that younger women will acquire salpingitis

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The correct answer is choice C. Chlamydia1 infections are NOT characterized by the ability of the organism to survive in the host extracellularly. Chlamydiae are obligate intracellular parasites that infect birds and mammals. Notice the answer choices all display clinical characteristics of chlamydial infections which are true except choice C which is a morphological feature. This represents an important test-taking strategy particularly dealing with "EXCEPT" questions: One of these is not like the others. When answering EXCEPT questions realize that all of the answer choices will have something in common except for the correct choice which will not be like the others. You need to look for any relationships between the answer choices and find the one that does not fit. In this case choice C is not a clinical charateristic like the other choices, therefore if you did not know the correct answer to this question choice C would be a good guess. Anyway, choice A - large numbers of assymptomatic carriers, choice B - frequent co-infection with gonorrhea, and choice D - the greater likelihood that younger women will acquire salpingiitis, are all characteristics of a chlamydial infection and cannot be the answer. Therefore the correct answer to question is C

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Each of the following is a histologic feature of malignant growth EXCEPT one. Which one is this EXCEPTION?A. AplasiaB. AnaplasiaC. PleomorphismD. HyperchromatismE. Abnormal mitosis

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The correct answer is choice A. Aplasia refers to a lack of cell growth or proliferation. Neoplasms are generally areas of uncontrolled growth and proliferation. All four other choices are associated with tumor growih. Anaplasia is loss of cell differentiation and tissue organization. Pleomorphism is wide variety of size and shape of nuclei and cells. Hyperchromatism is intense color and staining of nuclear material. Tumors also have abnormal, frequent and rapid mitoses. So the correct answer to question is choice A

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Each of the following is a risk factor in atherosclerosis EXCEPT one. Which one is this EXCEPTION?A. HeredityB. AlcoholismC. HypertensionD. Diabetes mellitusE. Hyperlipoproteinemia

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The correct answer is choice B. ALCOHOLISM Atherosclerosis refers to the narrowing of arteries due to the accumulation of fatty plaque along the arterial walls. A tendency for atherosclerosis can be inherited. In particular, the tendency toward hyperlipidemia (especially low density lipoproteins). This hyperlipidemia (hyperlipoproteinemia) can also be exacerbated by high fat diet, especially saturated fat. Hypertension, or high blood pressure, also is linked to a faster development and greater degree of atherosclerosis, in particular DIASTOLIC pressure. In diabetes, hyaline material may be deposited on aterial walls, reducing blood flow. Other risk factors include increasing age, cigarette smoking, obesity and sedentary lifestyle. Alcoholism is NOT a risk factor. So the correct answer is choice B

Front 226

Ectopic Cushing syndrome is usually caused by:A. an adenoma of the adrenal glandB. a carcinoma of the adrenal glandC. an adenoma of the anterior pituitaryD. exogenous administration of cortisolE. secretion by bronchogenic carcinomas and pancreatic neoplasms

Back 226

The correct answer is choice E. E. secretion by bronchogenic carcinomas and pancreatic neoplasms The answer can be correctly determined merely from the term ectopic, which refers to another, or unusual, area of the body. Tumors (usually adenomas) of the anterior pituitary (affecting ACTH) (choice C) or of the adrenal cortex (affecting cortisol release) are both direct causes of Cushing's syndrome (excess cortisol). The ectopic source of excess cortisol is that coming from an unusual source and place. Some lung and pancreas neoplasms can produce and secrete cortisol, and these tumors cause ectopic Cushing's syndrome. Iatrogenic Cushing syndrome is caused by administration of cortisol (choice D) to a patient, as a pharmaceutical agent (antiinflammatory, etc.)

Front 227

Esophageal varices are a common complication of1. portal hypertension.2. primary hypertension.3. mesenteric thrombosis.4. carcinoma of the esophagus

Back 227

The correct answer is choice 1. portal hypertension.Esophageal varices are distended veins in the esophagus. Through chronic liver damage such as that in alcoholic cirrhosis, portal circulation may be impeded and alternate channels bypassing the liver may become engorged with blood. Specifically, the portal blood drains by way of coronary veins of the stomach into esophageal veins and then into the azygous system of veins. Esophageal varices can lead to life threatening bleeding if damaged. Choice 2 is incorrect. Primary hypertension refers to high blood pressure of unknown etiology with readings of greater than 140/90. It does not lead to esophageal varices. Choice 3 is incorrect. Mesenteric thrombosis refers to a thrombosis or solidified blood clot forming in a mesenteric vessel. Thrombi may form emboli which are thrombi which travel to other vessels and lodge in those vessels. However, they will not cause esophageal varices. Choice 4 is incorrect. Carcinoma of the esophagus may lead to bleeding within the esophagus but this bleeding would not be hccause of esophageal varices. So the correct answer to question is choice 1.

Front 228

Ethylene oxide sterilization procedures usually require exposure times of:A. 20-30 minutesB. 1-2 hoursC. 2-3 hoursD. 8-10 hoursE. 24 hours

Back 228

The correct answer is choice D. D. 8-10 hours Ethylene oxide is used for sterilization of heat sensitive instruments and materials. Its advantage is that it does not melt, damage or corrode instruments, as heat may. Its disadvantages include long cycle time (8-10 hours) and additional time to air out the materials so that they do not contain ethylene oxide residue. 20-30 minutes is a common steam autoclave time. 1-2 hours is a common dry heat oven time. 24 hours was a time recommended for "cold sterilization" by chemicals. Cold sterilization is a misnomer, as it is actually high level disinfection

Front 229

Factors that predispose susceptible erythrocytes to sickling include all of the following EXCEPT:A. high glucoseB. low oxygenC. low pHD. dehydration

Back 229

The correct answer is choice A. NOT GLUCOSE Sickle cell disease is caused by one amino acid mutation (valine substitution for glutamine) in the hemoglobin chain. The resulting hemoglobin S chain is susceptible to deforming (sickling). Factors that increase sickling tendency include low oxygen (choice B), higher levels of hemoglobin S (as opposed to hemoglobin A), low pH (choice C), and dehydration (choice D). Glucose level does not affect this tendency

Front 230

Fat embolism is most often a sequela of1. fracture.2. infection.3. contusion.4. infarction.5. deep laceration

Back 230

The correct choice is choice 1, fracture. Fat embolism occurs in almost all patients who suffer severe trauma with multiple fractures. It commonly presents clinically as a sudden change in mental status and shortness of breath. Renal failure may follow. When single bones are fractured without concomitant severe trauma, fat embolism occurs most often with hip fractures. Femur fracture rnay also cause fat embolism, but more rarely. Various medical conditions are associated with fat embolism due to 10: abnormalities in fat physiology. These conditions include diabetes mellitus, pancreatitis and alcoholism. When significant fat embolism occurs, regardless of the cause, the prttient cames a grave prognosis. Infection (choice 2), contusion (choice 3), infarction (choice 4) and deep laceration (choice 5) are not associated with fat embolism unless these conditions lead to pathologic fracture of a long bone. Once again, the correct choice for question is choice

Front 231

Following the treatment of an oral infection with clindamycin, a patient develops antibiotic associated colitis. This infection is most commonly caused byA. Clostridium difficileB. Closrridium novyiC. Clostridium perfringensD. Clostridium ramosumE. Closrridium septicum

Back 231

The correct answer is A. Antibiotic induced colitis (Pseudomembranous Colitis) is characterized by severe persistent diarrhea, severe abdominal cramps and is caused by the toxin produced by Clostridia difficile (choice A). This choice is generally seen towards the end of a therapy; however, it may begin up to several weeks following discontinuation of therapy. The treatment of this form of colitis is to discontinue medication, provide fluid and electrolyte replacement, corticosteroids (systemic and/or via enema) as well as vancomycin or metronidazole. Clostridium perfringens (choice C) is the bacteria most commonly associated with the development of clostridial myonecrosis, otherwise known as gas-gangrene. This bacteria is also commonly associated with the development of food poisoning. Furthermore, this bacteria, as well as Clostridium novyi (choice B) and Clostridium septicum (choice E), are known to cause Clostridial tissue infections and bacteremias. Clostridium ramosum (choice D) may be found as part of the normal colonic flora in many individuals.

Front 232

For the majority of individuals, the initial infection with herpes simplex virus results in1. encephalitis as a young adult.2. a dermal rash in childhood.3. herpes labialis in puberty.4. a subclinical disease.5. genital herpes

Back 232

The correct choice is choice 4, a subclinical disease. Most individuals are infected with the herpes simplex virus by the time they are two years old. In 90% of those infected, the initial disease is asymptomatic or subclinical. In the remaining 10%, gingivostomatitis develops. This is characterized by multiple vesicle formation over the oral mucosa and lips. Occasionally the nasal cavity and cornea are affected as well. Very rarely, the primary infection may include encephalitis or a diffuse skin rash. Encephalitis does occur in young adults as stated in choice 1, but this does not usually result from primary infection. Rather, it usually occurs when latent herpes simplex virus infection is reactivated. Choice 2 is incorrect because, as stated, dermal rash is actually a rare complication of primary infection. It occurs in less than 1% of infected individuals. Herpes labialis, choice 3, is the hallmark of reactivated herpes, not of primary infection. This lesion is more commonly called a fever blister. It is a vesicular eruption on the lip which occurs when latent herpes simplex virus particles in the trigeminal ganglia resurface. Genital herpes, choice 5, is caused by a different herpes simplex virus than the one infecting children. Genital herpes is caused by herpes simplex virus II, whereas young children acquire herpes simplex virus I. Herpes simplex virus II is transmitted by sexual contact and it causes a recurrent, painful vesicular lesion on the genitalia. Infection with this virus is far less pervasive than infection with herpes simplex virus I and, consequently, genital herpes is not the most common manifestation of herpes simplex virus infection. Once again, the correct choice to question is choice 4.

Front 233

Generally, resistance of a bacterium to killing by heat is influenced by time and by temperature employed in growth of the culture. Another factor is the ability of the organism to1. form spores.2. withstand acid pH.3. produce protopiasts.4. undergo transformation.5. grow at elevated temperatures

Back 233

The correct answer is choice 1. Spore formation is employed by certain bacterial species as protection against harsh conditions, including elevated temperature. The spores known as endospores are formed primarily by genus Bacillus and genus Clostridium. Spores may also be formed under poor nutritional conditions such as depletion of the nitrogen or carbon source. Choice 2 is incorrect. The ability to withstand low pH is not directly connected to the ability to withstand high temperature. Choice 3 is incorrect. Protoplasts are wall-defective microbial forms or, basically, gram-positive bacteria without walls. They are especially a fragile and their formation would not aid in the temperature resistance of the organism. Choice 4 is incorrect. In transformation, recipient bacteria take up DNA fragments released from other donor bacterial cells. Transformation does not normally aid the bacteria to resist being killed by high temperature. Choice 5 is incorrect. Most bacterial organisms grow faster at elevated temperatures up to a given point. This property does not cause them to resist elevated temperature in the way that formation of a protective endospore would. So the correct answer to question is choice 1.

Front 234

Generally, the antibiotic of choice for prophylactic therapy covering dental procedures in a patient with a heart valve abnormality who is allergic to penicillin is1. ampicillin.2. lincomycin.3. tetracycline.4. streptomycin.5. erythromycin

Back 234

The correct answer is choice 5. erythromycin Antibiotic prophylaxis for dental procedures for patients with heart murmur, rheumatic heart disease or other valvular problems usually consists of two grams of oral penicillin one hour before the procedure and one gram six hours after the procedure. In the penicillin-allergic patient, erythromycin is the drug of choice, with one gram given one hour before the procedure and 500 mg six hours after. It should be noted in the choices that choice 1, ampicillin, would never be given to the penicillin-allergic patient as it is a form of penicillin. Choice 2, lincomycin, is a bacterial protein synthesis inhibitor and is similar in mode of action to erythromycin. However, it is not used as an antibiotic prophylaxis. Likewise, choices 3 and 4, tetracycline and streptomycin, are bacterial protein synthesis inhibitors, but are not used in this way for prophylactic therapy. So the correct answer to question is choice 5.

Front 235

Gout results from a metabolic defect in which of the following?A. FatB. PurineC. PigmentD. GlucoseE. Calcium

Back 235

The correct answer is choice B. In gout, the normal breakdown of purines results in the formation of uric acid. Purines are generally difficult to degrade, and excretion involves, primarily, making the purine more soluble so that it can be excreted. Uric acid is this more soluble purine ring form. Excess uric acid, in the form of sodium urate crystals, develops in gout, and these crystals collect in the synovial capsules of joints of the lower extremity, especially the big toe. Excess urate can be caused by excess production, insufficient excretion or some inborn error of purine metabolism. So the correct answer to question is choice B.

Front 236

Hashimoto thyroiditis is associated with all of the following EXCEPT:A. goiterB. nervousness and heat sensitivityC. plasma cell infiltrateD. increased TSHE. association with autoimmune diseases

Back 236

The correct answer is choice B. NOT nervousness and heat sensitivity. Hashimoto thyroiditis is probably autoimmune-related and is more common in patients with other autoimmune diseases (choice E). Histologically, lymphocytic and plasma cell infiltrates (choice C) are noted. The gland enlarges (goiter) (choice A) but produces little thyroxin due to damage to the secreting cells. and so all symptoms are those of hypothyroidism. Therefore, the patient is often cold and lethargic, rather than hot and nervous. Note that goiter can be produced by many causes, not only iodine deficiency. TSH levels are high (choice D), as the anterior pituitary senses low thyroxin and secretes TSH to stimulate the thyroid gland

Front 237

Hemophilia B is an X-linked recessive disorder where there is a deficiency of which of the following substances?A. Factor VIII antigenB. Factor VIII coagulantC. Factor IX coagulantD. FibrinogenE. Vitamin K

Back 237

The correct answer is C. Factor IX coagulant. Hemophilia B (Christmas disease, factor IX hemophilia) is a hereditary bleeding disorder caused by a deficiency of coagulation factor IX; this disorder is also known as "Christmas disease." Individuals with this disorder will typically have a prolonged PTT. A deficiency of the factor VIII antigen (choice A) is typically seen in von Willebrand's disease. This disease is the most common congenital disorder of homeostasis; it is characterized by a deficient or defective von Willebrand factor (vWF). Although factor VIII antigen levels are decreased, the coagulation factor VIII levels are generally normal. Hemophilia A is an X-linked recessive disorder where factor VIII coagulant levels are decreased (choice B) and factor VIII antigen levels are normal. Hemophilia A is the "classic type of hemophilia" affecting 1 in 10,000 males. The bleeding tendency of this disorder is related to the deficiency of the factor VIlI coagulant. Afibrinogenemia is a rare disorder caused by a severe deficiency of fibrinogen (choice D). In this disorder, both the prothrombin time and partial thromboplastin time are markedly prolonged. Vitamin K (choice E) plays a crucial role in coagulation by acting as a cofactor for the synthesis of the vitamin K dependent clotting factors: 11, VII, IX and X. When vitamin K is deficient, the clotting cascade is interrupted and the prothrombin time will be prolonged

Front 238

Herpes simplex virus type 1 is clinically most often associated with1. neural lesions.2. genital lesions.3. cervical carcinoma.4. oral and ocular lesions.5. none of the above

Back 238

The correct choice is choice 4, oral and ocular lesions. Herpes simplex I, or HSV-I infection, is one of the most common viral infections. Almost all individuals are infected between 6 and 18 months of life, but only a small proportion become symptomatic. Those who do develop gingiva stomatitis which is characterized by multiple vesicular lesions in and around the mouth. Vesicles may also erupt over the cornea and cause blindness. The recurrent form of HSV-I infection is extremely common. After the primary infection, the virus becomes latent in the dorsal root ganglia. At times of stress, it reactivates and causes the common fever blister. This is a vesicular lesion at the mucocutaneous border of the lip. Neural lesions, choice 1, are rare complications of HSV-I infection, though the advent of AIDS has made HSV-I neurologic disease a significant clinical entity. A neurologic illness caused by HSV-I is encephalitis. This may occur during primary infection or with reactivation. Genital lesions, choice 2, may occur with HSV infection. However, they are usually caused by herpes simplex virus II infection. HSV-II has also been implicated in the pathogenesis of cervical carcinoma along with other viruses, most notably the papilloma virus. HSV-I does not induce cervical carcinoma. Once again, the correct choice to question is choice 4

Front 239

Hypersensitivity to M. Tuberculosis is manifested by which of the following?A. NecrosisB. ExudationC. Epithelioid cellsD. Langhans' giant cellsE. Spreading of the initial focus

Back 239

The correct answer is choice A. The immune system normally resists primary infection by M. tuberculosis. Activated macrophages engulf the bacteria and wall them off into nodules called tubercles or granulomas. Calcified tubercles are called Ghon complexes. Langhans cells are fused macrophages, while epithelioid cells are modified macrophages. Both are involved in walling off chronic infections. If primary TB becomes reactivated, it is termed secondary TB. TB which spreads beyond the lungs, usually through the bloodstream, is known as miliary TB. However, secondary TB still present in the lungs, is often contained by the actions of the immune system. The resulting hypersensitivity reactions of the immune system, however, may destroy areas of lung tissue, causing necrosis of the lung parenchyma, visible as large dark areas on X-ray. So the correct answer to question is choice A.

Front 240

If a gram stain reveals the presence of gram negative diplococci, the infection is most likely caused by which of the following organisms?A. Campylobacter jejuniB. Haemophilus influenzaeC. Neisseria meningitidisD. Staphylococcus aureusE. Streptococcus pneumoniae

Back 240

The correct answer is C Neisseria meningitidis. The gram-stain is often a quick and easy way to assess the "type" of bacterial infection in a given patient. For example, if a gram stain reveals the presence of gram negative diplococci, the infection is most likely caused by the bacteria Neisseria meningitidis. Based on this information, a clinician can prescribe an antibacterial regimen that has excellent coverage against this particular bacteria. Campylobacter jejuni (choice A) can be described as microaerophilic, motile gram-negative rods. These bacteria commonly cause diarrhea. Haemophilus influenzae (choice B), which is commonly seen in adults with pneumonia, can be described as gram-negative, pleomorphic rods. Staphylococcus aureus (choice D) is a bacteria associated with a variety of infections, such as skin infections and upper respiratory infections. These organisms are commonly described as gram-positive cocci in clusters. Streptococci pneumoniae (choice E), as the name suggests, is a common cause of pneumonia. These organisms are gram-positive diplococci

Front 241

If a patient is diagnosed with mononucleosis, one would expect to see all of the following EXCEPTA. Atypical lymphocytes on the differentialB. LymphadenopathyC. Normal liver function testsD. Normal renal function testsE. Splenic enlargement

Back 241

The correct answer is C.NOT. Normal liver function testsMononucleosis is a condition caused by the Epstein-Barr virus. Frequently, individuals with this virus will present with fever, sore throat and severe malaise. In almost all cases of mononucleosis, liver function tests will be elevated. There is normally an increase of atypical lymphocytes on the differential (choice A). Lymphadenopathy (choice B) is also commonly seen in cases of mononucleosis. Although liver function tests are abnormal in patients with this disease, renal function tests are mostly within normal limits (choice D). Splenic enlargement (choice E) is commonly seen in more than half of the cases of mononucleosis

Front 242

If a woman contracts an infection caused by Treponema pallidum during pregnancy, the child is at an increased risk for the development of which of the following?A. Genital herpesB. Gray teeth and brittle bonesC. KernicterusD. Koplik's spotsE. Widely spaced, peg shaped incisors

Back 242

The correct answer is E. Treponema pallidum is the causative organism of syphilis. The transmission of Treponema pallidum from a mother with syphilis to her fetus across the placenta can occur at virtually any stage of pregnancy. Signs and symptoms of late congenital syphilis occur 2 years after birth; the appearance of Hutchinson's teeth affect the upper central incisors resulting in notched, widely spaced, peg-shaped incisors (choice E). Other congenital effects include the appearance of "mulberry" molars or the poorly developed cusps of sixth-year molars. Genital herpes (choice A), inthe mother, can result in the development of mucocutaneous lesions on the lip of theperioral skin in the neonate as well as the development of CNS infections in the neonate. A bacterial infection treated with a tetracycline during pregnancy can result in permanent tooth discoloration (grayish teeth) (choice B), tooth enamel defects, and retarded bone growth in infants and children. Kernicterus (choice C) is a neurological disorder seen in infants born to mothers who receive sulfonamide antibiotic during pregnancy. Koplik's spots (choice D) are seen in individuals who have contracted rubeola; these spots are small, irregular, grayish-white lesions on upper buccal mucosa and are considered pathognomonic for this disease

Front 243

If an individual has a tumor that is secreting excess amounts of antidiuretic hormone, the pathological effect on the body would beA. DehydrationB. HypertensionC. Kidney failureD. Vasodilation of the peripheral blood vesselsE. Polycythemia

Back 243

The correct answer is B. The gist of this question is as follows: What happens when excess antidiuretic hormone is secreted? Antidiuretic hormone (ADH) or vasopressin is a hormone that is typically released when there is a fall in blood pressure or there is a rise in the blood concentration of electrolytes. The primary function of antidiuretic hormone is to decrease the amount of water lost through the kidneys through increased renal reabsorption of water. Since this hormone functions to increase blood pressure, an excessive amount of this hormone in the blood would lead to hypertension or high blood pressure. Dehydration (choice A) would not occur when antidiuretic hormone blood levels increase since the primary function of ADH is to prevent water loss. Kidney failure (choice C) would occur if there was insufficient blood flow to the kidney; increasing the blood volume would increase blood flow to the kidney. Antidiuretic hormone is known to cause vasoconstriction of the peripheral blood vessels; not vasodilation of the peripheral blood vessels (choice D). Polycythemia (choice E) is a condition characterized by an increased number of red cells in the blood

Front 244

If an individual was diagnosed with emphysema, one would expect to see all the following EXCEPTA. CyanosisB. Decreased diffusing capacity of the lungsC. Increased anteroposterior diameterD. Increased total lung capacityE. Minimal sputum production

Back 244

The correct answer is A. NOT Cyanosis Emphysema is a chronic condition characterized by shortness of breath and an inability to tolerate physical exertion. The underlying problem of this disease is due to the destruction of alveolar surfaces and inadequate surface area for carbon dioxide and oxygen exchange. In emphysema, there is minimal ventilation-perfusion imbalance because the individual is continually hyperventilating and therefore able to keep blood gases within the normal range. In other words, cyanosis rarely develops. The primary etiology of this disease is related to the decreased diffusing capacity of the lungs (choice B). Patients with emphysema typically develop a "barrel chest"; the individuals anteroposterior diameter increases (choice C). In emphysema, the FEV1 is decreased; both the total lung capacity (TLC) (choice D) and residual volume (RV) are increased. Minimal sputum production (choice E) is commonly seen in patients with emphysema.

Front 245

If clindamycin is a lincosamide antibiotic used in the treatment of oral infections commonly caused by anaerobic bacteria, it would most likely be used in the treatment of an infection caused byA. Bacteroides fragilisB. Corynebacterium diphtheriaC. Escherichia coliD. Proteus mirabilisE. Streptococcus mutans

Back 245

The correct answer is A. Bacteroides fragilisClindamycin is an antibiotic primarily used in the treatment of serious anaerobic infections (including serious oral infections) when other less toxic alternatives are not recommended. This question is essentially asking, "Which of the following is an anaerobic bacteria?" Bacteroides fragilis (choice A) is an anaerobic bacteria commonly associated with the development of gingival diseases. Corynebacterium diphtheria (choice B) and Streptococcus mutans (choice E) are both gram positive organisms; Streptococcus mutans is the most common cause of dental caries. Both Escherichia coli (choice C) and Proteus mirabilis (choice D) are gram-negative organisms

Front 246

Immunosuppressed patients are particularly prone to develop severe oral disease caused by1. Candida albicans.2. Actinomyces israelii.3. Pneumocystis carinii.4. Streptococcus mutans.5. Streptococcus salivarius

Back 246

The correct choice is choice 1, candida albicans. Oral candida albicans infection, also called candidiasis or moniliasis, is a marker of immunosuppression. Candida is a ubiquitous organism and it does not cause infection in the normal host. However, if the immune system is compromised due to AIDS, congenital disease, renal transplantation therapy or leukemia, or if the normal flora ol the oral cavity has been cleared by long-term treatment with broad spectrum antibiotics, oral candidiasis results. This disease present as white curd-like lesions of the tongue and buccal mucosa. In patients with oral candidiasis and risk factors for AIDS, esophageal candidiasis should be suspected. An esophagram should be obtained if the patient has dysphagia. Esophageal candidiasis is a treatable disease and it establishes the diagnosis of AIDS by CDC criteria. Actinomyces israelii, choice 2, causes infections of soft tissue which lead to abscess formation. This disease usually follows oral trauma or aspiration of saliva. It can occur in a normal host and not a marker of immunosuppression. By contrast, Pneumocystis carinii, choice 3, causes disease only in immunocompromised patients. In fact, infection with this organism is sufficient for a diagnosis of AIDS. Pneumocystis, unlike candida, does not cause infection in the mouth. It is a lung pathogen which causes severe pneumonia with a large alveolar to arteriole oxygen gradient. Strep. mutans, choice 4, was already discussed. This organism is responsible for the development of dental caries. It causes disease in the normal as well as the immunocompromised host. Strep. salivarius, choice 5, is an alpha-hemolytic Streptococcus. This organism can cause endocarditis which is a fairly common disease in IV drug abusers and those with valvular heart disease. It is not typically an infection of immunocompromised patients, though these patients may have a particularly poor prognosis if they do develop Strep. endocarditis. Once again, the correct choice to question is choice 1.

Front 247

Impetigo is a superficial infection of the skin most commonly caused byA. Group A streptococciB. Staphylococcus aureusC. Streptococcus agalactiaeD. Streptococcus mutansE. Streptococcus pyogenes

Back 247

The correct answer is A. Group A streptococci. Impetigo is described as a type of superficial cellulitis primarily caused by Group A Streptococci (choice A) followed by Staphylococcus aureus (choice B). This condition is most commonly seen in hot, humid weather, which can aid in the colonization of the skin. When minor trauma occurs, such as a scratch, the bacteria enter the superficial layer of the skin, which subsequently results in the development of an infection. Since this is a highly communicable disease, it can be spread through close contact. Patients typically present with small, fluid filled (pus) vesicles that readily rupture and form the golden "crusts" characteristic of this disorder; pruritus is common. Streptococcus agalactiae (choice C) is known to cause septicemia in infants as well as bovine mastitis. Dental caries is a destructive disorder of the hard tissues of the teeth primarily caused by Streptococcus mutans (choice D). Streptococcus pyogenes (choice E) causes scarlet fever, epidemic "sore throat", tonsillitis and many other infections in humans.(extra note- group A strep is strep pyogenes....Staph would be correct)

Front 248

In a patient with parathyroid adenoma, you would expect to find:A. high serum calciumB. neuromuscular excitabilityC. tetanyD. cardiac conduction defectsE. hyperphosphatemia

Back 248

The correct answer is choice A. high serum calcium. A parathyroid adenoma usually causes excess secretion of parathyroid hormone. This hormone, which stimulates osleoclasts, causes calcium to be removed from tissues, especially bone, and placed back into the blood. A result should be hypercalcemia with subperiosteal resorption, and sometimes kidney stones. All of the other choices listed would be due to hypocalcemia (low serum calcium), including that caused by excess calcitonin, or loss of parathyroid function. The answer choices B, C, D and E review standard results of low blood calcium

Front 249

In addition to Neisseria meningitidis which of the following is a significant cause of meningitis?A. Streptococcus faecalisB. Streptococcus pyogenesC. Streptococcus pneumoniaeD. Staphylococcus aureusE. Staphylococcus epidermidis

Back 249

The correct answer is choice C. Streptococcus pneumoniae is a significant cause of meningitis and is the number one cause of meningitis in the elderly. Choice A - Streptococcus faecalis is part of the normal fecal flora and causes urinary tract infections in hospitalized patients; rare cause of subacute endocarditis. It is not a significant cause of meningitis. Choice B - Streptococcus pyogenes (Group A, B-Hemolytic), is an obligate human parasite spread person-to-person by respiratory secretion via droplets, direct contact with the skin, or fomites. Clinical manifestations are characterized as suppurative or nonsuppurative predominantly involving pharyngitis and various skin infections. It is not a significant cause of meningitis. Choice D - Staphylococcus aureus is a common infectious agent of humans and tends to cause localized or toxin-mediated disease. It should not be considered normal flora, but it does transiently colonize the nasopharynx, skin, and vagina of up to 30% of the population. It is not a significant cause of meningitis. Choice E - Staphylococcus epidermis is most commonly a nosicomial pathogen. Clinical manifestations are typically related to instrumentation and procedures and include endocarditis and urinary tract infections. It is not a significant cause of meningitis. Therefore the correct answer to question is C.

Front 250

In Goodpasture syndrome, antibodies are directed against the basement membranes of both the:A. heart and lungB. liver and kidneyC. kidney and lungD. kidney and pancreasE. liver and pancreas

Back 250

The correct answer is choice C. kidney and lung Goodpasture syndrome involves both a necrotizing hemorrhagic pneumonitis and a focal glomerulonephritis. Antibodies are formed to common antigens in the basement membranes of both organs. This leads eventually to renal failure, uremia, and pulmonary disease. In immunofluorescent studies, immunoglobulins can be seen lining the basement membranes of both organs

Front 251

In order for a virus to infect a host cell, it must first absorb to the cell surface. This involves1. phagocytic activity by the cell.2. energy output on the part of the cell.3. insertion of virally specified glycoproteins into the host cell membrane.4. a specific interaction between a viral surface component and a specific receptor on the cell membrane.5. all of the above

Back 251

choice is 4 a specific interaction between a viral surface component and a specific receptor on the cell membrane.In order for virus particles to infect a cell, they must enter the cell. The first step of entry is to attach to the cell membrane surface. This is the process of adsorption, not absorption as the question states. Anyway, it occurs as the virus adsorbs at a specific cell receptor site. The virus loses one viral polypeptide in the process. Choice 1 is incorrect. The cell does not phagocytize or ingest the virus. Very few human cells have phagocytic ability. Choice 2 is incorrect. No energy use in the form of ATP is needed for adsorption. Choice 3 is incorrect as the virus coat is protein, but not glycoprotein. Choice 4 is correct as the viral protein will attach only to specific membrane receptor sites. So the correct answer to question is choice 4.

Front 252

Inadequate immobilization atter a bone fracture is likely to result in1. lipping.2. a pannus.3. pseudoarthrosis.4. Heberden's nodes

Back 252

The correct choice is choice 3, pseudoarthrosis. Bone healing following fracture occurs in distinct stages. In the first stage, blood at the fracture site coagulates and a fibrin meshwork or procallus is elaborated. This meshwork becomes coated with fibroblasts, cartilage and bone matrix, resulting in fibrocartilaginous callus formation. With time, the fibrocartilaginous callus is resorbed and an osseous callus is laid down. The new bone is then remodelled along stress lines. The healing process requires adequate immobilization to reach completion. If the bone is moved during repair, the osseous callus may fail to form, leaving a fibrocartilaginous callus at the fracture site. This callus is flexible and the bone may appear to have a false joint or pseudoarthrosis. Lipping, choice 1, is the slang term for osteophyte formation. Osteophytes are bony outgrowths that occur along the ridges of bones in degenerative joints. They may fracture and produce joint immobility or pain. A panus, choice 2, is a mass of chronic inflammatory tissue which forms in the joints of patients with rheumatoid arthritis. As the disease progresses, the panus erodes into surrounding bone and may lead to fusion of the joint. Heberden's nodes, choice 4, are bony bumps on the distal phalanges of the hands in patients with osteoarthritis. Once again, the correct choice to question is choice 3.

Front 253

Increased functional demand on the heart produces increased size of the myocardium by1. hyperplasia.2. hypertrophy.3. calcification.4. fatty infiltration.5. increased amounts of fibrous connective tissue.

Back 253

The correct answer is choice 2. hypertrophy, Increased functional demand on the heart, for example, through exercise will cause enlargement of the heart muscle or myocardium. However, this enlargement does not occur through hyperplasia or increase in cell number. It is believed that the number of cardiac muscle cells or fibers in the heart remains fairly constant after birth and that increases in myocardial size result from hypertrophy or added length or width of the cardiac muscle cells. Choices 3, 4 and 5 are all incorrect. Fatty infiltration, increased fibrous connective tissue and calcification are all pathologic conditions. They are not normal responses of the heart to increased demand which will help the heart meet the increased needs of the body. So the correct answer to question is choice 2.

Front 254

Insufficient intake of protein, despite sufficient caloric intake, results in the condition:A. marasmusB. kwashiorkorC. beriberiD. scurvyE. pernicious anemia

Back 254

The correct answer is choice B. Kwashiorkor occurs when the body receives sufficient caloric intake (energy value) but insufficient protein content. This can occur if a diet is limited, for example, to one of a few starchy food items. Symptoms include edema, anemia, dermatoses (desquamation and pigment changes), hepatomegaly, and anergy. Marasmus (choice A) refers to insufficient caloric intake and results in cachexia, muscle wasting, loss of subcutaneous fat, and failure to thrive. Beriberi (choice C) occurs through lack of thiamine, a B vitamin. Symptoms include nervous system deterioration and heart dilation. Scurvy (choice D) occurs through lack of vitamin C. Symptoms include poor wound healing and bleeding gingiva. Pernicious anemia (choice E) results from Vitamin B12 (cobalamin) deficiency and leads to a megaloblastic anemia and neurologic damage

Front 255

Insufficient numbers of circulating polymorphonuclear leukocytes (PMNs) is best described as:NBDE Part I released questions - Microbiology-PathologyInsufficient numbers of circulating polymorphonuclear leukocytes (PMNs) is best described as:A. leukemiaB. neutropeniaC. leukopeniaD. pancytopeniaE. leukocytosis

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The correct answer is choice C. Neutropenia (choice B) describes the state of insufficiennt numbers of neutrophils (PMNs), whereas leukopenia is a more general term referring to low levels of leukocytes. Leukemias (choice A) are neoplasms resulting in elevated levels of immature white blood cells in circulation. Pancytopenia (choice D) refers to an overall diminishment of all cell types from the bone marrow, including red blood cells, white blood cells, and platelets. Leukocytosis (choice E) refers to an elevated leukocyte level, such as that following infection (as opposed to that found in leukemia). Causes of neutropenia may include problems with the bone marrow (aplastic anemia or drug suppression), increased destruction of PMNs, or effects of drugs (chloramphenicol or sulfonamides).

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Jaundice does NOT result from which of the following?NBDE Part I released questions - Microbiology-PathologyJaundice does NOT result from which of the following?1. Gallstones2. Hepatitis A3. Hemolytic anemia4. Vitamin K deficiency5. Carcinoma of the common bile duct

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Good WorkThe correct choice is choice 4, vitamin K deficiency. Jaundice refers to the yellowish pigmentation of the sclera, skin and mucous membranes in individuals with elevated serum bilirubin levels. Any condition which causes hyperbilirubinemia may cause jaundice. The synthesis of coagulation factors VII, IX and X are vitamin K dependent. Therefore, vitamin K deficiency causes a coagulopathy. It does not lead to jaundice. Vitamin K deficiency is present, however, in many jaundiced individuals. This occurs because conditions which cause jaundice may also cause a vitamin K deficiency. An example of such a condition is liver failure. The liver synthesizes bile salts which are essential for vitamin K absorption from the gut. The liver also clears bilirubin from the blood. In liver failure, both of these functions are compromised and a coagulopathy with jaundice may result. Gallstones, choice 1, and carcinoma of the common bile duct, choice 5, cause jaundice when they obstruct bile flow into the duodenum. Bilirubin is a major component of bile and it cannot be adequately excreted in these conditions. As a consequence, it overflows into the bloodstream. Bilirubin which has been processed by the liver is called conjugated bilirubin. It is assayed as direct bilirubin when liver function tests are requested. It is direct bilirubin that is elevated in gallstones and carcinoma of the bile duct. Indirect bilirubin or unconjugated bilirubin is devated in the bloodstream when bilirubin enters the bloodstream before being processed by the liver. This occurs in hemolytic anemia, choice 3. When red cells are hemolyzed, globin chains are released from hemoglobin molecules. They are converted to bilirubin by a sequence of enzymes and the increased bilirubin load cannot be adequately cleared by the liver. Hepatitis A, choice 2, causes an elevation in both direct and indirect bilirubin. Direct bilirubin is released into the blood when hepatocytes are destroyed. As a consequence of hepatocellular necrosis, the clearance of indirect bilirubin is reduced. Indirect hyperbilirubinemia follows. Both the direct and the indirect hyperbilirubinemias cause jaundice. Indirect hyperbilirubinemia is very dangerous in newborns. Indirect hyperbilirubin deposits in the brain and causes a neurologic condition known as kernicterus. Once again, the correct choice for question is choice 4.

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Keloids are composed predominantly ofNBDE Part I released questions - Microbiology-PathologyKeloids are composed predominantly of1. adipose tissue.2. collagen fibers.3. granulation tissue.4. caseous necrotic debris.

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Good WorkThe correct answer is choice 2. Keloids are formed when abnormal increases of collagen occur during connective tissue repair. They can result in bulging tumor-like scars. Choice 1 is incorrect. Adipose tissue is fat storage tissue which would contain high levels of lipid but not collagen. Choice 3 is incorrect. Granulation tissue is undifferentiated repair tissue which forms in wound healing. It does not contain excess collagen and keloids are not formed from granulation tissue. Granulation tissue contains vascular and epithelial cells, fibroblasts, macrophages and mast cells. Choice 4 is incorrect. Caseous necrotic debris refers to debris which is necrotic, being composed of dead and decaying cells. Caseous necrotic debris is cheese-like in appearance, soft and friable. It is common in tuberculosis granulomas, fungal infections and central areas of certain tumors. So the correct answer to question is choice 2.

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Lecithinases are produced byNBDE Part I released questions - Microbiology-PathologyLecithinases are produced by1. Bacillus anthracis.2. Clostridium perfringens.3. Salmonella schottmulleri.4. Mycobacterium tuberculosis.5. Corynebacterium diphtheriae.

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Good WorkThe correct answer is choice 2. Clostridia, in general, are anaerobic, gram positive motile rods. They are responsible for the diseases botulism, tetanus, and gas gangrene. Clostridia spores are usually introduced into wounds by soil or feces. In an anaerobic environment caused by decaying or necrotic tissue, the spores will germinate and the resulting cells produce a number of toxins. They can include hemolysins and necrotizing toxins. Clostridium perfringens in particular produces an alpha toxin which is a lecithinase. It damages cell membranes by splitting lecithin. Clostridia can also produce collagenases , DNAase and enterotoxins . So the correct answer to question is choice 2.

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Left-sided heart failure or shock may be associated withNBDE Part I released questions - Microbiology-PathologyLeft-sided heart failure or shock may be associated with1. pneumoconiosis.2. bronchiectasis.3. pulmonary edema.4. pulmonary emboli.

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Good WorkThe correct answer is choice 3. Pulmonary edema can be caused by left-sided heart failure. As the left ventricle reduces the volume of blood pumped, a backup of fluid and pressure occurs through the left atrium, pulmonary vein and lungs, with resulting pulmonary edema. Choice 1, pneumoconiosis, is not associated with left-sided failure, but instead is related to dust inhalation, including coal and asbestos, and is a restrictive lung disease. Choice 2, bronchiectasis, refers to abnormal dilation of bronchi and bronchioles caused by chronic necrotizing infection. It is not associated with left-sided failure. Choice 4. pulmonary emboli, are due to small coagulated areas of blood traveling to the lungs usually from the large veins of the legs and pelvis. They travel back to the right side of the heart and then in the pulmonary artery to the lungs. However, they are not associated with left-sided heart failure. So the correct answer to question is choice 3.

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Lysozyme can attack bacterial cells byNBDE Part I released questions - Microbiology-PathologyLysozyme can attack bacterial cells by1. degrading their flagella.2. inactivating their ribosomes.3. preventing the transpeptidation reaction.4. breaking the bond between N-acetyl glucosamine and N-acetyl muramic acid.

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Good WorkThe correct answer is choice 4. Lysozyme is found in tears, saliva and nasal secretions. It attacks bacterial cell walls composed of peptidoglycans. Peptidoglycans contain polymers of repeating N-acetylglucosamine and N-acetylmuramic acid joined by B 1-4 linkages. Lysozyme breaks these B 1-4 linkages, thus dissolving the cell walls. Lysozyme is particularly effective on grampositive bacteria. Choice 1 is incorrect. Lysozyme has no effect on flagella. Choice 2 is incorrect. Lysozyme does not reach the interior of the bacterial cytoplasm where ribosomes are located. It only acts on the cell wall. Choice 3 is incorrect. Lysozyme has no effect on transpeptidation which involves protein formation. As mentioned previously, it acts only on the peptidoglycans of the cell wall. So the correct answer to question is choice 4.

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Malignant epithelial cells have an increased number and wider distribution of which of the following receptors?NBDE Part I released questions - Microbiology-PathologyMalignant epithelial cells have an increased number and wider distribution of which of the following receptors?A. IL-1B. LamininC. HistamineD. ComplementE. Immunoglobulin

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Good WorkThe correct answer is choice B. When normal cells become malignant, a number of changes can occur in their receptors. The number and distribution of normal receptors may change, and the tumor cell may express new receptors not previously shown. These are known as tumor-specific antigens. This concept is the basis for potential immunological treatment of tumors. In this case, malignant epithelial cells increase the number of receptors known as laminin receptors, on the cell surface. In general, for tumors caused by chemical carcinogens, when cells of identical genetic background are transformed with the same chemical carcinogen, each tumor formed has its own unique tumor-specific antigens. When cells are transformed by an oncogenic virus, all new tumors express the same tumor-specific antigen. Cells transformed by different viruses exhibit different tumor-specific antigens. So the correct answer to question is choice B.

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Methicillin-resistant Staphylococcus aureus (MRSA) organisms are:NBDE Part I released questions - Microbiology-PathologyMethicillin-resistant Staphylococcus aureus (MRSA) organisms are:A. resistant to all antibioticsB. a form of untreatable TBC. common causes of nosocomial infectionsD. streptococciE. none of the above

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Good WorkThe correct answer is choice C. MRSA refers to methicillin-resistant Siaphylococcus aureus. These organisms cause difficult-to-control infections, often in hospital patients and health care workers. Staph organisms that were resistant to most penicillins were formerly killed by methicillin, a penicillinase-resistant drug. However, more strains of Staphylococcus are now resistant to methicillin, and infections by these organisms are difficult to control. Vancomycin is sometimes used. The resistance of MRSA organisms is probably due to their exposure to several antibiotics in the hospital environment, and patients in hospitals are most susceptible. Hospital-based infections are known as nosocomial. A similar phenomenon is found in multiple drug resistant tuberculosis (MDRTB).

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Microcytic hypochromic anemia is most often due toNBDE Part I released questions - Microbiology-PathologyMicrocytic hypochromic anemia is most often due to1. infection.2. malabsorption.3. folate deficiency.4. chronic blood loss.5. a genetic abnormality.

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Good WorkThe correct choice is choice 4, chronic blood loss. Microcytic hypochromic anemia may be due to a variety of causes. The most common cause is iron deficiency. Iron deficiency may result from blood loss secondary to acute or chronic hemorrhage or even physiologic bleeding such as menses. It also occurs when demand increases, a common occurrence in pregnant women. In impoverished countries, iron deficiency results from decreased iron intake. Iron deficiency may also result from malabsorption, choice 2, but this is uncommon except in Crohn's disease. Microcytic hypochromic anemia also occurs when the individual cannot utilize body iron stores. This occurs in chronic inflammatory diseases and in cancer. Genetic abnormalities, choice 5, may cause this type of anemia as well. The prevalence of these genetic abnormalities is very low, however, when compared to the prevalence of chronic blood loss. Infection, choice 1, is not a cause of anemia though it may lead to conditions which cause anemia such as malabsorption or disseminated intravascular coagulopathy. Folate deficiency, choice 3, causes a megaloblastic anemia. It is a common finding in chronic alcoholism and other diseases associated with malnutrition. Once again, the correct choice to question is choice 4.

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Most bacterial endotoxins are composed ofNBDE Part I released questions - Microbiology-PathologyMost bacterial endotoxins are composed of1. pure lipids.2. pure proteins.3. pure carbohydrates.4. mucoprotein complexes.5. lipoprotein-polysaccharide complexes.

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Good WorkThe correct choice is choice 5, lipoprotein-polysaccharide complexes. Endotoxins are composed of lipid, protein and sugar moieties, but only the lipid portion called lipid A is responsible for the biologic effects of this molecule. Endotoxin is found only in gram-negative bacteria. It is a component of the outer membrane which is released into the circulation when the bacterium is killed by the host defense system. Circulating endotoxin has a variety of effects on vascular permeability and clotting mechanisms, and may E ultimately lead to hypotension and disseminated intravascular coagulopathy. Endotoxin differs from the various exotoxins produced by many strains of bacteria in that exotoxins are generally composed of protein alone. Examples of exotoxins include tetanospasmin which is responsible for tetanus and enterotoxin which causes cholera. Mucoproteins, choice 4, are protein polysaccharide complexes. Unlike endotoxin, they lack lipid. Once again, the correct choice to question is choice 5.

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Osteomyelitis is most commonly caused by1. Actinomyces bovis.2. Borrelia vincentii.3. Nocardia asteroides.4. Staphylococcus aureus.5. Mycobacterium tuberculosis.

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Good WorkThe correct choice is choice 4, Staphylococcus aureus. Osteomyelitis is an infection of bone which may or may not involve the bone marrow. It usually begins when a blood-borne organism, most commonly Staph aureus, is deposited in bone. Osteomyelitis can also occur following penetrating trauma in which the organism is introduced directly into bone. Osteomyelitis most commonly occurs in children and adolescents and it requires a protracted course of IV antibiotics and occasionally surgical debridement. Any organism can cause osteomyelitis. In addition to Staph. aureus, various strains of Streptococci, Pneumococci and Neisseria commonly cause osteomyelitis. Pseudomonas aeruginosa is a common pathogen among drug abusers. With the advent of AIDS, other organisms have been found frequently in the bone marrow, including Mycobacterium tuberculosis, choice 5, and atypical Mycobacteria including Mycobacterium avium intracellulare. Actinomyces, choice 1, rarely enters bone. More frequently, it causes abscesses in connective tissue which forms sinus tracts in the skin. Borrelia, choice 2, are spirochetes like T. pallidum, the agent causing syphilis. Borrelia has been linked to relapsing fever, skin and mucous membrane ulcers and lung lesions, but is not associated with osteomyelitis. Nocardia, choice 3, is primarily a pathogen in the lung where it causes suppurative fibrotic and necrotic lesions which may be cavitary and diffuse. Once again, the correct choice to question is choice 4.

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Organisms that exhibit dimorphism and grow on Sabouraud's medium are1. fungi2. bacteria.3. mycoplasmas.4. rickettsiae.5. spirochetes.

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Good WorkThe correct choice is choice 1, fungi. Dimorphism is a phenomenon demonstrated by some species of fungi. The term literally means "two forms." Fungi which are dimorphic can be found as either a mold or a yeast. Molds are collections of multiple tubular structures called hyphae. They are multicellular conglomerates with hyphae specialized for various functions such as reproduction or nutrient absorption. Yeasts, by contrast, are unicellular. They are quite small and tend to be spherical. They show no specialization of function. Fungi which cause disease in humans are usually dimorphic. They are yeasts when invading the host, but become molds when cultured. Fungi are generally cultured on Sabouraud's agar. This agar supplies the fungi with glucose and peptone as nutrients, and inhibits the growth of bacteria with chloramphenicol and cycloheximide. Fungi are slow growing. Consequently, fungal cultures may take weeks to produce positive results. Bacteria, choice 2, are dimorphic in that they can exist as unicellular organisms or as spores. They are selectively inhibited by Sabouraud's agar, however. Mycoplasma are very small microorganisms which resemble bacteria in their ability to grow on artificial media, though they do not grown on Sabouraud's agar. They show dimorphism insofar as they can be found as spherical bodies or as filaments. Rickettsia, choice 4, are obligate intracellular microorganisms. They are always found as Coccobacilli either singly or in pairs. They do not display dimorphism. Rickettsia are not grown on agilr. They require cell culture for proliferation. Spirochetes, choice 5, do not show dimorphism. They are always observed as long and thin spiralled organisms. The spirochetes which cause disease in humans cannot be cultured in artificial media. They will only grow in live organisms. Once again, the correct choice to question is choice 1.

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Opsonization may occur as a component of the humoral immune response to1. virulent Streptococcus pneumoniae.2. intracellular microorganisms.3. infections by viruses.4. nucleic acids.5. none of the above.

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Good WorkThe correct choice is choice 1, virulent Streptococcus pneumoniae. Opsonization refers to the coating of microorganisms by antibody and/or complement to enhance phagocytosis. Because the process usually involves antibody, it is considered pan of the humoral response to infection. Antibody can bind only to extracellular organisms. It does not penetrate the plasma membrane. Therefore, choice 2 is incorrect. Viruses, choice 3, usually cause intracellular infection. Consequently, the humoral arm of the immune system does not play an important role in the defense against viral infection. Nucleic acids, choice 4, are not in and of themselves infectious agents. When foreign nucleic acids enter the bloodstream, they are cleared by humoral immune mechanism as are foreign proteins and carbohydrates. However, opsonization is a term reserved for the ingestion of organisms, not molecules. Opsonization is of primary importance in the host's defense against encapsulated extracellular organisms such as Streptococcus pneumoniae. In fact, individuals who cannot produce adequate antibodies for opsonization often succumb to overwhelming Streptococcal infection. Once again, the correct choice to question is choice 1.

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Of the following sexually transmitted diseases, the LEAST common is:A. syphilisB. Neisseria gonorrheaC. lymphogranuloma venereum (LGV)D. chlamydiaE. non-gonococcal urethritis (NGU)

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Good WorkThe correct answer is choice C. Gonorrhea caused by Neisseria gonorrhoeae (choice B), Chlamydia (choice D), and nongonococcal urethritis (NGU) (choice E) are all extremely common sexually transmitted diseases (STDs). NGU is caused by either Ureaplasma or Mycoplasma, whereas chlamydia is caused by C. trachomatis. Lymphogranuloma venerum (LGV) is also caused by a strain of C. trachomatis and results in a syndrome presenting with swollen infected lymph nodes in the groin. However, this disease form is very uncommon. Syphilis (choice A), caused by Treponema pallidum, is less common than the first three but more common than LGV.

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Nephrolithiasis is most likely to result from which of the following diseases?1. Hyperpituitarism2. Cushing's disease3. Hyperparathyroidism4. Paget's disease of bone

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Good WorkThe correct choice is choice 3, hyperparathyroidism. Nephrolithiasis is the medical term for kidney stones. Kidney stones may be composed of a variety of constituents. Most stones are calcium containing and most patients with calcium stones have elevated levels of calcium in their urine and normal serum calcium levels. About 10% of patients, however, will have increased serum calcium and this results most commonly from hyperparathyroidism. Other causes of hypercalcemia include Cushing's disease, choice 2, and Paget's disease, choice 4. Hyperpituitarism, choice 1, may cause hypercalcemia if increased ACTH is a component of the disorder. Kidney stones may also be composed of uric acid. These stones occur in patients with gout and in those with leukemia i receiving chemotherapy. Magnesium stones also mur. These can be quite large. They can fill the entire renal pelvis. Magnesium stones are formed during urinary tract infection with Proteus species. Proteus splits urea to form ammonia which readily crystallizes with magnesium to form a very solid crystal. Cysteine stones are the rarest form of renal stone. They occur in patients with a genetic id impairment in the transport of the amino acid cysteine. Cysteine accumulates in the kidney and precipitates around a nidus. Once again, the correct choice to question is choice 3.

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Neoplasms of which of the following organs have been shown to be hormonally dependent?1. Liver2. Parotid3. Prostate4. Pancreas

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Good WorkThe correct answer is choice 3. Benign prostatic hypertrophy is probably hormonally related. It involves the formation of large nodules which obstruct the urethral canal. In addition, prostatic carcinoma is also thought to be hormonally related, with androgens in particular being involved. Not mentioned here, but useful in other questions about prostatic carcinoma, is the fact that the tumor can be detected through elevated acid phosphatase produced by the prostatic epithelium. Choices 1,2 and 4 do not produce neoplasms with hormonally dependent growth. So the correct answer to question is choice 3.

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Myasthenia gravis is caused by dysfunction of the1. motor nerves.2. smooth muscle.3. sensory nerves.4. skeletal muscle.5. myoneural junction.

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Good WorkThe correct answer is choice 5. Myasthenia gravis is an autoimmune disease in which IgG is directed against the acetylcholine receptor of the neuromuscular junction. Clinical signs include muscular weakness, especially of muscles supplied by cranial and peripheral nerves. It typically affects young women primarily, and generally will not cause sensory problems. Be careful of answers 1 through 4 which state that the disease affects the muscles or nerves when, in fact, it affects the junction between them. So the correct answer to question is choice 5.

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Multiple myeloma signs and symptoms include all of the following EXCEPT:A. lower than normal blood viscosityB. increased susceptibility to infectionC. accumulation of Bence-Jones proteinsD. proteinuriaE. "punched out" lesions on x-ray

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Good WorkThe correct answer is choice A. In multiple myeloma, large numbers of excess abnormal immunoglobulins are formed (monoclonal gammopathy). Proteins deposit in bone, joints, and kidney, leading to pain, proteinuria (choice D), and nephropathy. The inability to produce normal antibodies increases susceptibility to infection (choice B). Bence-Jones proteins (choice C) appear in both the blood and urine. The excess blood protein results in a hyperviscous blood, also leading to circulatory damage. "Punched-out" lesions (choice E) refer to characteristic radiolucencies on x-ray caused by loss of calcified tissue.

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Multiple drug resistance is related most closely to1. viruses.2. plasmids.3. transformation.4. cell chromosomes.

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Good WorkThe correct choice is 2, plasmids. Plasmids are self-replicating, autonomous segments of DNA located in the cytoplasm of many bacteria. These gene packages code for proteins which have a variety of functions. In Clostridium, for example, the exotoxin responsible for botulism is encoded by a plasmid. Similarly, the exfoliation produced by Staph. aureus is actually a plasmid product. Plasmids provide Pseudomonas species with the capacity to metabolize hydrocarbons, and they make some strains of E. Coli resistant to invasion by bacteriophages. Most relevant to patient care are the plasmids which confer drug resistance. These plasmids are referred to as R factors, where R stands for resistance. R factors encode enzymes which inactivate various antibiotics. The most well known of these is penicillinase. This enzyme hydrolyzes the beta-lactam ring of the penicillin molecule. Other R factors encode enzymes which inactivate aminoglycosides through phosphorylation or acetylation, or inactivate tetracycline by modifying the permeability of the bacterial membrane. Virtually every antibiotic has an associated R factor and it can be both challenging and frustrating to treat a patient infected with a resistant organism. Viruses, choice 1, have not been shown to introduce genetic material into bacteria which can encode resistance factors. Choice 4 is incorrect because plasmids are separate from the chromosomal DNA. Plasmids do not encode proteins responsible for cell growth and development as do chromosomes. Transformation, choice 3, refers to the process whereby an organism becomes virulent through the acquisition of a set of genes which encodes virulence factors. This process plays no role in drug resistance, though resistance factors can be passed from one organism to another as can virulence factors. Repeating the correct choice to question, the correct choice is choice 2.

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Most rickettsial diseases produce severe illness in humans because rickettsiae1. produce potent exotoxins.2. are destructive for endothelial cells.3. are particularly destructive to cutaneous tissues.4. are primarily neurotropic and cause extensive damage in certain CNS centers.

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Good WorkThe correct answer is choice 2. Rickettsiae are small bacteria that are obligate intracellular parasites. Except for Q fever, rickettsial diseases are transmitted by arthropods; that is, insects, fleas and ticks. Rickettsiae multiply in the endothelial cells of small blood vessels and produce vasculitis, so choice 2 is correct. Vascular lesions may appear on the skin, choice 3, but Rickettsiae cause equal or greater damage to the heart, brain and other organs. Choice 4 is incorrect because their main target cell is endothelial, not neural, even though they may damage the brain. The brain damage is due to vascular problems caused by the infected endothelium. Choice 1 is incorrect. The Rickettsiae produce endotoxins, not exotoxins. So the correct answer to question is choice 2.

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Sjögren's syndrome is characterized by all of the following EXCEPT:A. xerostomiaB. atrophied parotid glandsC. dry, burning eyesD. peripheral neuropathyE. sicca syndrome

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Good WorkThe correct answer is choice B. Sjogren syndrome is an autoimmune disease characterized by xerostomia (dry mouth) (choice A), dry eyes (choice C), with a burning or dry cracked sensation, peripheral neuropathy (choice D), and vasculitis. The parotid gland, rather than being shrunken as might be expected, is actually larger than normal. This is due to fibrosis of the gland, in which glandular tissue is replaced by fibrous connective tissue with no secretory function. The primary form is known as sicca syndrome (choice E), but other secondary forms exist, in which the disease is associated with another autoimmune diseases.

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Shock during infection with gram-negative bacteria is most likely caused by1. an exotoxin.2. an endotoxin.3. ribonuclease.4. a capsular antigen.5. a flagellar antigen.

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Good WorkThe correct answer is choice 2. An endotoxin is a material found in gram negative bacterial cell walls. It consists of LPS or lipopolysaccharide and is highly toxic to animals. Of the lipid and polysaccharide segments of LPS, the lipid part, known as lipid A, is the toxic fragment. Endotoxin will cause fever in individuals after a 60-90 minute latent period after injection. Other symptoms include leukopenia or reduced white cell count, hypoglycemia, hypotension and shock. Impaired blood supply to vital organs, triggering of complement and intravascular coagulation are also possible. So the correct answer to question is choice 2.

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Rheumatic fever may leave the heart seriously damaged because of1. primary infection of the heart valves with Group A streptococci.2. secondary infection of the heart valves with Group A streptococci.3. damage to the heart valves thought to be a result of hypersensitivity to hemolytic staphylococci.4. damage to the heart valves thought to be a result of hypersensitivity to Group A streptococci.

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Good WorkThe correct choice is choice 4, damage to the heart valves thought to be a result of hypersensitivity to group A streptococci. Rheumatic fever is a disease of young children which has been on the rise in recent years. It is characterized by migratory polyarthritis involving large joints, chorea or involuntary limb movements, carditis, subcutaneous nodules, and a skin rash. It occurs several weeks after group A, beta-hemolytic Strep. pharyngitis. Rheumatic fever may be followed by rheumatic heart disease which involves the mitral and aortic valves. Stenosis of these valves results when fibrous tissue is deposited. The carditis of rheumatic fever which often progresses to rheumatic heart disease is thought to be secondary to antibody cross-reactivity. During the primary pharyngitis, antibodies form against the group A streptococci. These antibodies react against an antigen present in myocardial tissue and inflammation of the heart, or carditis, results. Primary infection of the heart valves with group A streptococci mentioned in choice 1 does not occur in rheumatic fever. When Strep species do cause endocarditis, the pathogenic organisms are usually alpha-hemolytic streptococci. Secondary infection of the heart valves, choice 2, occurs when organisms are camed by the blood stream to the heart from a distant site of infection. In rheumatic fever, the blood and heart valves are sterile. The disease is caused by immunologic mechanisms, not by bacterial invasion. Choice 3 is incorrect because, as mentioned, rheumatic fever follows Strep. infection, not Staph. infection. Once again, the correct choice to question is choice 4.

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Respiratory syncytial virus (RSV) infection differs from influenza infections in thatA. RSV can be treated with amantadine.B. RSV causes disease primarily in infants.C. influenza virus is difficult to transmit.D. RSV can be prevented with effective vaccines.E. secretory IgA is not effective in preventing disease.

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Good WorkThe correct answer is choice B. RSV differs from Influenza infections in that RSV causes disease primarily in infants. Choice A - is incorrect because Amantadine is effective only in type A influenza infections and acts to decrease symptoms. Choice C - is incorrect because Influenza virus is relatively easy to transmit via inhalation. (RSV is transmitted via aerosolized droplets and fomites). Choice D - is incorrect because RSV cannot be prevented with effective vaccines. (for Influenza vaccines composed of inactivated virus are designed to elicit immunity against the existing serotypes in the population. Vaccines change from year to year based on the particular serologic determinants of the virus). Choice E - is incorrect because IgA is found in the gut, breast milk, lungs and tears. It would therefore be present in both RSV and influenzae. Therefore the correct answer to question is B.

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Recurrent herpes labialis occurs in people who1. are hypersensitive to herpesvirus.2. have been infected with herpesvirus and who have antibodies against the virus.3. have been infected with herpesvirus but who fail to produce antibodies against the virus.4. None of the above

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Good WorkThe correct choice is choice 2, have been infected with the herpes virus and who have antibodies against the virus. Herpes labialis is the medical term for the common fever blister or cold sore. It occurs when the herpes simplex virus number I is reactivated after a latency period. During the latency period, it was present in a dormant state in the trigeminal ganglion. Upon reactivation, the virus travels down the trigeminal nerve to produce localized disease in the distribution of the nerve, most commonly at sites in and around the oral cavity. Reactivation is a poorly understood process. Immunoglobulins present in the patient's serum which were induced by the virus upon primary infection do not prevent reactivation. They do, however, attenuate the disease which tends to be less severe than the primary infection. Choice 1 is incorrect because individuals who are hypersensitive to the virus would produce increased quantities of IgG upon initial exposure. Recurrent herpes labialis would be exceptionally mild or even subclinical in these people. Choice 3 is incorrect because it has been well documented that individuals with recurrent herpes simplex virus I infection have antibodies to the virus which were induced upon primary infection. Once again, the correct choice to question is choice 2.

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Prolonged administration of streptomycin may result in damage to which of the following nerves?1. Optic2. Facial3. Auditory4. Trigeminal

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Good WorkThe correct answer is choice 3. Streptomycin is an antibiotic that inhibits bacterial protein synthesis and was first isolated from the mold Streptomyces. It binds to the 30S bacterial ribosomal subunit. It is used commonly against Staph aureus, Mycobacterium tuberculosis, and synergistically with penicillin against organisms such as Enterococci and Streptococci. Side effects have included a narrow toxic to therapeutic ratio, renal toxicity and ototoxicity, meaning damage to the hearing through a damaging effect on the auditory nerve. So the correct answer to question is choice 3.

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Progressive massive fibrosis of the lung is characteristic of1. silicosis.2. anthracosis.3. actinomycosis.4. hemosiderosis.5. bronchiectasis.

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Good WorkThe correct answer is choice 1. Silicosis is a condition caused by chronic exposure to silica such as in mining, sand blasting or road construction. It begins as nodular fibrosis but may expand to massive fibrosis. Choice 2 is incorrect. Anthracosis is caused by chronic exposure to coal, polluted air or cigarettes. Black pigment is deposited in lung parenchyma. However, disease is not always present. Choice 3 is incorrect. Actinomycosis is an infectious disease caused by Actinomyces species. Choice 4 is incorrect. Hemosiderosis in the lungs is found in idiopathic pulmonary hemosiderosis, an uncommon condition characterized by cough, weight loss and hemoptysis which is coughing of blood. Choice 5 is incorrect. Bronchiectasis refers to abnormal dilation of bronchi and bronchioles caused by chronic necrotizing infection. So the correct answer to question is choice 1.

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Production of bone in scar tissue occurs by1. dysplasia.2. anaplasia.3. neoplasia.4. metaplasia.5. fibroplasia.

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Good WorkThe correct answer is choice 4. Metaplasia refers to reversible change in tissue type from one to another; in this case, from scar tissue to osteoblastic tissue. Choice 1, dysplasia, refers to early pathologic tissue changes, especially abnormal proliferation of atypical cells. Choice 2, anaplasia, is another stage of cellular disorder and refers to loss of cell differentiation and tissue organization. Choice 3, neoplasia, refers to the growth of masses of abnormal tissue, either malignant or benign. Fibroplasia, choice 5, refers to abnormal formation of fibrous connective tissue. So only choice 4, metaplasia, has to do with a change in type of cell produced from one normal type to another in the same location. So the correct answer to question is choice 4.

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Patients with Bruton's agammaglobulinemia principally suffer from infections caused by1. fungi.2. viruses.3. parasites.4. pyogenic bacteria.5. tubercle bacilli.

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Good WorkThe correct answer is choice 4. Bruton's agammaglobulinemia is an X-linked trait which results in failure of maturation of B cells. Therefore, no immunoglobulins can be produced and bacterial infections are extremely difficult to defend against. As an X-linked trait, it appears almost entirely in males and presents early in childhood, with recurring bacterial infections. The affected person has normal T cell function which should indicate some ability to defend against fungi, viruses and parasites, choices 1,2 and 3, and against the Mycobacteria, including the tubercle bacilli, choice 5. So the correct answer to question is choice 4.

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Patients receiving chemotherapy for leukemia are particularly prone to develop oral1. candidiasis.2. actinomycosis.3. blastomycosis.4. histoplasmosis.5. coccidioidomycosis.

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Good WorkThe correct answer is choice 1. Candidiasis is a fungal infection caused by the yeast Candida albicans. It is a condition often found in the immunosuppressed and in patients taking antibiotics for long periods of time. Candida is a naturally occurring member of the normal oral flora and grows opportunistically. In cases of leukemia, chemotherapy is used to reduce abnormal white blood cell counts. This, combined with the fact that the present immune system in the leukemic patient operates poorly, leads to the increased risk of opportunistic infections by yeast and other organisms. Choice 2 is incorrect. Actinomycosis is an infection by Actinomyces israelii. It is not especially increased in the leukemic patient. Choice 3 is incorrect. Blastomycosis is a fungal disease and it affects the lung and skin primarily and it is not especially found in leukemic patients. Choice 4 is also incorrect. Histoplasmosis is another fungal disease, often asymptomatic. It is not especially found in leukemic patients. Choice 5 is incorrect. Coccidioidomycosis is another fungal disease often affecting the lungs, but not especially common in leukemic patients. Again, the correct answer to qucstion is choice 1.

Front 285

The alum adjuvant employed, in many vaccines acts biologically in tissues to1. serve as a local inflammatory stimulus.2. prolong antigen release to immunocompetent cells in the region.3. Both (1) and (2) above4. Neither (1) nor (2) above

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Good WorkThe correct choice is choice 3, both 1 and 2 above. An alum is a double salt consisting of aluminum sulfate and a sulfate of an alkaline earth element such as sodium or potassium. An adjuvant is a chemical compound which facilitates a specific reaction. Alum adjuvants are used in vaccines to augment the immunogenicity of the vaccine. They increase inflammation and decrease blood flow at the injection site. This has the effect of bringing many lymphocytes and macrophages into a region with a high local concentration of the immunogen. The vasoconsuiction prevents the cells of the immune system and the antigen from diffusing away from the site. Through inflammation and vasoconstriction, the alum increases the likelihood that effective immunization will result. Once again, the correct choice to question is choice 3.

Front 286

The alteration of Corynebacterium diphtheriae to a virulent strain by the transfer of DNA temperate bacteriophage is1. mutation.2. sexduction.3. conjugation.4. recombination.5. lysogenic conversion.

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Good WorkThe correct answer is choice 5. Lysogenic conversion refers to a process in which phages known as temperate phages infect a bacterial cell and can convert the bacterium from one type to another. Phage conversion or lysogenic conversion is thus defined as the acquisition of new properties as a result of phage infection. It differs from transduction in that the genes controlling the new properties are only found in the phage DNA and are not incorporated in the host cell genome. Phage recombination refers to a bacterium becoming infected with two different types of phage particles and then when lysed, releasing phage particles with combined properties of both phage types. Mutation is a general term for a change in DNA structure. Recombination is a general term for DNA rearrangement. Conjugation refers to mating between two types of bacterial cells with exchange of genetic material. So the correct answer to question is choice 5.

Front 287

The aerosol produced during operative dental procedures is likely to contain a predominance of1. yeasts and spirochetes.2. spirochetes and rod forms.3. spirochetes and rickettsiae.4. gram-positive microorganisms.5. gram-negative rod forms and spirochetes.

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Good WorkThe correct choice is choice 4, gram-positive microorganisms. The aerosol produced during oral surgery will seflect the flora present in the oral cavity. If the patient is healthy and has not been on antibiotics, the flora will consist mainly of gram-positive organisms. This is true because under normal conditions, the mouth is populated predominantly by Streptococci. Yeasts, spirochetes and gram-negative rods are also present in the oral cavity, but at low concentrations. Consequently. an aerosol produced during oral surgery will contain small concentrations of these microorganisms. Rickettsia, mentioned in choice 3, are not present in the oral cavity under normal circumstances. In illness, the flora of the mouth often changes. AIDS patients and patients on broad spectrum antibiotics often have yeasts of the Candida species in abundant quantities in their mouths. An aerosol from these patients would likely show a predominance of yeasts as opposed to gram-positive cocci. Similarly, patients with syphilitic chancres in their mouths may have many spirochetes in their aerosol. Gram-negative rods may colonize the oral mucosa in hospitalized patients and give rise to gram-negative aerosols in these patients. Aerosolization of rickettsia occurs in systemic rickettsia1 disease, but this is primarily due to lung invasion. Oral lesions in rickettsia are not common. Once again, the correct choice to question is choice 4.

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The absence of cellular differentiation is characteristic of1. anaplasia.2. metaplasia.3. hyperplasia.4. hypertrophy5. inflammation

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Good WorkThe correct choice is choice 1, anaplasia. Anaplastic tumors are usually more aggressive than tumors which show cellular differentiation. Anaplastic cells can be thought of embryonic cells. They show a tremendous capacity for replication. Differentiated cells are more complex and specialized. They do not replicate as readily. In fact, many differentiated cells such as neurons do not replicate at all. Metaplasia, choice 2, occurs when tissues of one organ begin to look like tissues of another organ. Metaplasia usually occurs in response to a chemical injury. Barrett's esophagus, for example, occurs when acid from the stomach refluxes into the esophagus, causing the esophageal mucosa to transform into gastric mucosa. Another example of metaplasia occurs in smokers. Cigarette smoke causes bronchial mucosa to transform from the normal ciliated columnar epithelium to stratified squamous epithelium. Hyperplasia, choice 3, occurs when the number of cells in a tissue increases. Normal growth requires hyperplasia such as when the breasts enlarge at puberty, but hyperplasia can also be a pre-malignant condition. Hypertrophy, choice 4, occurs when cells increase in size. Body builders cause hypertrophy of muscle cells by lifting weights. Inflammation, choice 5, is the infiltration of tissue by a combination of neutrophils, lymphocytes, macrophages and tissue fluid. It occurs when tissues becomes infected and in some noninfectious diseases as well. Once again, the correct choice to question is choice 1.

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The ability of mammalian organs to regenerate after injury is best demonstrated by the1. lung.2. liver.3. heart.4. brain.5. kidney.

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Good WorkThe correct choice is 2, liver. Cells can be classified into three types according to their rate of replication. Labile cells rapidly proliferate and do so continuously. All epithelial cells are labile cells as are cells of the hematopoietic system. Stable cells replicate very slowly, but they maintain the capacity to replicate quickly in the face of injury. Liver cells are the stable cells which are most adept at replication. A rat liver, for example, can regenerate 75% of its mass in one week. Other stable cells include alveolar cells in the lung, choice 1, and kidney cells, choice 5. Heart and brain cells, choices 3 and 4, belong to the third class of cells, the permanent cells. These cells show virtually no capacity to replicate after injury. Following myocardial infarction, for example, the necrotic tissue is replaced with fibrous tissue, not with healthy myocardial cells. Similarly. patients who suffer strokes rarely show improvement in functioning. When they do, it is usually due to decreased cerebral edema, not to regeneration of neurons. Once again, the correct choice to question is choice 2.

Front 290

Tetany may result from hypofunction of which of the following glands?1. Thyroid2. Hypophysis3. Parathyroid4. Adrenal cortex5. Adrenal medulla

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Good WorkThe correct choice is choice 3, parathyroid. Parathyroid hormone is an important hormone in calcium metabolism. It acts to elevate serum calcium levels by stimulating osteoclastic activity and bone dissolution and by activating vitamin D which absorbs calcium from the gut and by increasing renal resorption of calcium. Hypofunction of the parathyroid gland leads to decreased parathyroid hormone secretion and, consequently, decreased serum calcium levels. Hypocalcemia is associated with a variety of symptoms, including tetany. Tetany is a syndrome characterized by muscle spasms, cramps and seizures. Hypothyroidism, choice 1, is associated with generalized lethargy and slowing of mental and motor functions. Signs of this disease include coarse skin, dry brittle hair, hoarse voice, and peripheral and periorbital edema. Hypofunction of the hypophysis or pituitary, choice 2, can present in a variety of ways. The pituitary secretes thyroid-stimulating hormone, adrenal corticotropic hormone, growth hormone, follicle-stimulating hormone, luteinizing hormone, prolactin, antidiuretic hormone, and oxytocin. Hypopituitarism can be manifested as deficiency syndromes of any or all of these hormones. These deficiency syndromes include hypothyroidism, adrenal insufficiency, growth retardation, ovarian failure, loss of libido, and diabetes insipidus. Hypofunction of the adrenal cortex, choice 4, is most commonly due to adrenal suppression secondary to the administration of steroids or from infiltration of the adrenals by tumor. It is manifested clinically as weakness, weight loss, hypotension, hyperpigmentation and salt craving. Hypofunction of the adrenal medulla, choice 5, is not associated with a distinct clinical syndrome. So the correct choice to question is choice 3.

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Tetanus or lockjaw is a disease caused by which of the following species of bacteria?A. BacteroidesB. ClostridiumC. CorynebacteriaD. MycobacteriumE. Nocardia

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Good WorkThe correct answer is B. The Clostridium genus of bacteria are sporulating anaerobic bacilli that are known to produce potent exotoxins and toxic enzymes. Tetanus or lockjaw is a worldwide disease that is caused by the exotoxin produced by the bacteria Clostridium tetani; hence the name tetanus. The classic muscular spasm in tetanus involves the face, neck, or other parts of the body. The name lockjaw is derived from the muscular contractions that rigidly close or "lock" the jaws together. Bacteroides (choice A) are gram negative pleomorphic rods commonly found in the natural cavities of animals and humans. Outside of their native haunts, the bacteria cause hemolytic and necrotizing lesions. Corynebacteria (choice C) are gram positive aerobic microbes. The major organism of this genus is Corynebacteria diptheriae, which is known to cause diphtheria. Diphtheria is a degenerative disease affecting the nervous system, heart, kidneys and cortex of the adrenal gland. Mycobacterium (choice D) is the genus commonly associated with the acid-fast bacteria Mycobacterium tuberculosis; the organism known to cause tuberculosis.

Front 292

Ten days after hospitalization for a large, incapacitating myocardial infarct, a 50-year-old man suddenly develops paralysis of the right side of his body. The best explanation for his brain damage is1. rupture of a congenital aneurysm of the circle of Willis.2. brain abscess from necrosis of the myocardium.3. detachment of a bacterial embolus from the pulmonic valve.4. detachment of a mural thrombus from the right ventricle.5. detachment of a mural thrombus from the left ventricle.

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Good WorkThe correct answer is choice 5. It is not uncommon for myocardial infarction to lead to a thrombus formation on the walls of the heart. This thrombus may break off as an embolus and travel to the brain with subsequent brain damage. This is what probably has occurred in this case. So choice 5 is correct. We choose 5 over 3 and 4 because emboli travelling to the brain must come from the left side of the heart or systemic side. Emboli from the right side, either the right ventricle or pulmonic valve, would travel to the lungs and remain there. Choice 2 is incorrect. Brain abscess is not a normal complication of myocardial infarction. Choice 1 is also incorrect. Although rupture of a congenital aneurysm is possible, it is certainly not the most likely cause in this case. Remember that emboli are common post-MI problems and that they often travel from the left heart to the brain. So the correct answer to question is choice 5.

Front 293

Suppuration is mainly the result of the combined action of four factors. Which of the following is NOT one of these factors?1. Necrosis2. Presence of lymphocytes3. Collection of neutrophils4. Accumulation of tissue fluid5. Autolysis by proteolytic enzymes

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Good WorkThe correct answer is choice 2. Suppuration involves the formation of pus in an infected area. Pus is formed from tissue fluid, cellular debris, dead and dying neutrophils and dead bacteria. Necrosis refers to decay and decomposition of living material so it is included here. Accumulation of tissue fluid is also included. Neutrophils will kill microorganisms through the use of lysosomal enzymes but may also lyse themselves, which is autolysis. These dead neutrophils build up in the pus. Choice 2, lymphocytes are not involved and choice 2 is our answer. Lymphocytes may produce antibodies from plasma cells which are derived from B lymphocytes or they may be involved in cell mediated cytotoxicity as in T lymphocytes. However, they are not found in pus. So the correct answer to question is choice 2.

Front 294

Striated muscle, smooth muscle, and cardiac muscle have in common the fact that1. hyperplasia of these elements is common.2. hypertrophy is a common response to injury.3. they have a limited capacity to regenerate.4. they need a constant high O2 concentration to function.

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Good WorkThe correct answer is choice 3. Muscle tissue cells are generally thought to not increase in number over time. Most researchers feel that the number of individual muscle cells does not increase after birth but that growth of individual cells or fibers occurs both in length and in width. When injured, the muscle will attempt to repair itself using nearby satellite cells to produce new fibers. However, it is not very efficient and often some scar tissue replaces the injured muscle tissue. So choice 3 is correct. Choice 1 is therefore incorrect as hyperplasia refers to production of many new cells. Choice 2 is incorrect. Hypertrophy or growth in size of individual cells or fibers occurs especially after exercise but not often after injury. Choice 4 is incorrect although muscle function is more efficient under aerobic conditions and although anaerobic respiration cannot occur indefinitely without fatigue. For limited amounts of time a muscle can contract using anaerobic respiration. Lactic acid accumulates in the muscle as an anaerobic waste product and is later oxidized as the so-called oxygen debt is repaid. So the correct answer to question is choice 3.

Front 295

Sterilization refers to which of the following?1. Absence of all living forms2. Inhibition of bacterial growth3. Removal of pathogenic bacteria only4. Removal of pathogenic bacteria, viruses, and fungi

Back 295

Good WorkThe correct answer is choice 1. Sterilization refers to the absence of all living organisms including bacteria, fungi, viruses and bacterial spores. Choice 2 is incorrect. Inhibiting bacteria only is not sufficient. Nor is killing pathogenic bacteria only, choice 3. Choice 4 sounds better in that it includes bacteria, fungi and viruses but sterilization will kill all organisms, pathogenic or non pathogenic and will also kill spores as well. In fact, to test completeness of sterilization by autoclave, a spore test is usually performed where bacterial spores which are difficult to kill, are autoclaved and checked to see if they can be cultured after the autoclaving. So the correct answer to question is choice 1.

Front 296

Sterilization of surgical instruments that are sensitive to heat can best be accomplished by:A. High level chemical disinfectant (glutaraldehyde)B. Ethyl alcoholC. Ethylene glycolD. Ethylene oxideE. Autoclave (121 C)

Back 296

Good WorkThe correct answer is choice D. The standard chemical sterilizer uses ethylene oxide as the sterilant. The process occurs at room temperature, and is especially useful for materials which are damaged by heat, such as some rubbers, fabrics or cloths. Glutaraldehyde can be used as a high level disinfectant, but is not considered to be a sterilant because it is not sporicidal, except after extensive periods of time. It is not the standard chemical sterilant. Ethyl alcohol is a low to medium level surface disinfectant. Ethylene glycol is automotive antifreeze. The steam autoclave is the standard sterilizing method, generally used for any material unless there is some contraindication to it. Its high temperature (higher than boiling water) and moisture can damage heat sensitive instruments, dull sharp edges and corrode some metals.

Front 297

Sterilization of surgical instruments that are sensitive to heat can be accomplished by using1. phenol.2. an autoclave.3. ethyl alcohol.4. ethylene oxide.

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Good WorkThe correct answer is choice 4. Sterilization of dental instruments is usually accomplished through either a dry heat autoclave (dry clave), a steam autoclave, or a chemical autoclave (chemiclave). The chemical most often used for chemical sterilization is ethylene oxide. Choice 1, phenol, is incorrect. Phenol based disinfectants may be used for high level disinfection. However, these disinfectants do not sterilize, that is, they do not kill all organisms including spores. Choice 2 is incorrect. Autoclaving is a possible method of sterilization. However, it involves the use of high pressure steam so instruments sensitive to heat cannot be autoclaved. Choice 3, ethyl alcohol is incorrect. Ethyl alcohol cannot be used to sterilize and it is also not a high level disinfectant. So the correct answer to question is choice 4.

Front 298

Sterilization is best defined as:A. Inhibition of bacterial growthB. Killling of all viral formsC. Removal of pathogenic bacteriaD. Absence of all life formsE. Death of viral and bacterial organisms

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Good WorkThe correct answer is choice D. When a material or object is sterilized, no living organisms remain on it. That includes bacteria, viruses, fungi, protozoans and, in particular, bacterial spores. Most of the choices listed mention only a few types of organisms. Note that whether the organisms are pathogenic or not is irrelevant. The benchmark for effective sterilization is the ability to kill bacterial spores. Disinfection is generally not sporicidal, while sterilization is. This is also the basis for the use of bacterial spores (of Bacillus stearothermophilus) to test autoclave effectiveness.

Front 299

Staphylococcus aureus is classified as a:A. Gram + aerobeB. Gram - aerobeC. Gram + anaerobeD. Gram - anaerobe

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Good WorkThe correct answer is choice A. Staphylococcus aureus is a Gram-positive aerobic coccus. It produces coagulase and is hemolytic. The most common lesion associated with S. aureus is the abscess. Abscesses tend to fill with liquefied necrotic tissue and inflammatory cells and point in the direction of least tissue resistance.

Front 300

Soap acts as a disease prevention chemical primarily by:A. Bacteriocidal effect on microbesB. Bacteriostatic effect on microbesC. Removal of microbesD. Dehydration of microbesE. Inhibition of microbial growth

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Good WorkThe correct answer is choice C. Soap acts as an emulsifying agent, dissolving grease and oil which hold microorganisms on the skin. Due to this property, most microorganisms are removed from the hands during washing, and hand washing is considered to be the single most effective infection control measure in the dental office. Bacteriostatic effect refers to inhibition of bacterial growth, rather than direct killing of bacteria. For example, some antibiotics are bacteriostatic. Bacteriocidal refers to direct killing of bacterial cells. Many disinfectants and antibiotics are bacteriocidal. While soap and some soap additives may have either of these effects, they are not the primary effects of soap. Dehydration of microbes is one method by which dry heat autoclaves kill microorganisms. Denaturation of protein is another. Soap does not kill bacteria this way.

Front 301

The characteristic finding in Actinomyces infections is:A. sulfurB. tangled masses of filaments with "clubs"C. mycolic acid cell wallsD. atypical bone loss around first molars

Back 301

Good WorkThe correct answer is choice B. Be careful in answering this question. Actinomyces infections, which may follow oral surgical procedures, often are accompanied by draining fistulas and material described as "sulfur granules." These granules are creamy-yellowish and consist of tangled masses of Actinomyces filaments with club-like extensions. They also have necrotic debris associated with them. They are not, however, composed of sulfur (choice A) and have only a sulfur-like appearance. Note that mycolic acid cell walls (choice C) are found mostly in mycobacteria, and that choice D describes juvenile periodontitis, which is caused by Actinobacillus, not Actinomyces.

Front 302

The characteristic lesion of primary syphilis is the:NBDE Part I released questions - Microbiology-PathologyThe characteristic lesion of primary syphilis is the:A. gummaB. maculopapular rashC. hard chancreD. saddle nose

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Good WorkThe correct answer is choice C. A hard chancre is a raised hard area near the entrance of the spirochete into the body, often on the mouth or genitalia. It is described as a raised ulcer with a clean, hard base. It is the characteristic lesion of primary syphilis. Secondary syphilis is characterized by a red maculopapular rash (choice B), especially over the back and shoulders, and pale papules in the mouth, axilla, and anogenital region. Meningitis, nephritis, or hepatitis may also be present at this stage. Both primary and secondary syphilitic lesions are infectious. The characteristic lesion of tertiary syphilis is the gumma (choice A), a granulomatous lesion often found in skin bones or liver. Symptoms of congenital syphilis include Hutchinson's teeth, mulberry molars, saddle nose (choice D), and interstitial keratitis.

Front 303

The chemical nature of bacterial endotoxins is a1. lipid.2. protein.3. complex carbohydrate.4. lipopolysaccharide complex.5. low molecular weight polypeptide.

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Good WorkThe correct answer is choice 4. Endotoxins are complex lipopolysaccharides derived from cell walls and liberated when the bacteria lyse. Endotoxins are taken up by reticuloendothelial cells or endothelial cells and are degraded or neutralized. Clinically, they lead to fever, leukopenia, and in serious cases, to hypotension, shock, intravascular coagulation and death. All other answer choices are incorrect as endotoxin is a lipopolysaccharide. It's not a lipid, protein, complex carbohydrate or low molecular weight polypeptide which would also be a protein like answer choice 2. So the correct answer to question is choice 4.

Front 304

The earliest changes in rheumatoid arthritis occur in the1. villi.2. synovia.3. attached ligaments.4. articular cartilage.5. subarticular bone.

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Good WorkThe correct choice is choice 2, synovia. Rheumatoid arthritis, or RA, is a systemic autoimmune disease involving primarily the joints, lungs, heart and blood vessels. The most common form of the disease is a crippling arthritis involving the proximal interphalangeal joints of the hands and feet. It affects approximately 3% of all women, but less than 1 % of men. In the early stages, the synovia become infiltrated with acute and chronic inflammatory cells. The synovial fluid contains an abundance of neutrophils. As the disease progresses, the synovia thickens and becomes vascularized. The number of chronic inflammatory cells increases dramatically and foci of necrosis can be found. This mass of vascularized inflammatory tissue is called the panus. The panus erodes into the adjacent articular cartilage, choice 4, and subsequently involves the supporting ligaments, choice 3. In the final stages, the panus erodes into bone, choice 5. Fibrous tissue replaces the joints and mobility is lost at that stage. Villi, choice 1, are not present in either the normal or diseased joint. Once again, the correct choice to question is choice 2.

Front 305

The effectiveness of autoclaving is best determined by1. culturing bacterial spores.2. culturing the water reservoir.3. thermocouples (temperature recording devices).4. indicators that change color at elevated temperatures.

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Good WorkThe correct answer is choice 1. Whether the autoclaving is effective or not depends primarily on whether all bacteria, fungi, virus and spores have been killed. Regardless of the temperature and pressures measured, it would still be an assumption to say that all living organisms are killed unless these organisms are tested for. In particular, spores are cultured because they require the most rigorous autoclaving conditions in order to be killed. If we do not find spores, we can safely assume that there are no bacteria, fungi or viruses as well. Choices 3 and 4 are incorrect as these devices might be malfunctioning, and are only indirect and not direct indicators of living organisms. Choice 2 is incorrect. We should culture an instrument or possible source of spores to see if they have been killed. It is possible that the autoclaving water might be sterile, but an instrument might contain spores if not sufficiently autoclaved. So the correct answer to question is choice 1.

Front 306

The etiologic basis of Hashimoto's thyroiditis is1. autoimmune.2. bacterial infection.3. hereditary enzyme deficiency.4. premalignant diffuse hyperplasia.5. secondary to hyperpituitarism.

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Good WorkThe correct answer is choice 1. Hashimoto's thyroiditis is a chronic lymphocytic thyroiditis involving a goitrous enlargement of the gland due to lymphocytic and plasma cell infiltrates. It is the leading cause of hypothyroidism in the U.S. It is believed to have an autoimmune etiology. In this condition, thyroid-stimulating hormone or TSH is increased and, later, decreased T4 production occurs with accompanying malaise and fever. The gland is symmetrically swollen and firm. Choices 2, 3, 4 and 5 are therefore all incorrect as they are not etiologic factors in Hashimoto's thyroiditis. So the correct answer to question is choice 1.

Front 307

The etiology of megacolon (Hirschsprung disease) is:A. benign muscle neoplasmB. malignant muscle neoplasmC. imperforate anusD. absence of ganglion cellsE. defective autonomic neurotransmitters

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Good WorkThe correct answer is choice D. Megacolon is discovered shortly after birth when the newborn exhibits vomiting, nausea, distention, and constipation. The newborn cannot eliminate feces (pass meconium). Microscopically, ganglion cells of Metssner and Auerbach plexi are missing. The muscle of the colon cannot relax between peristaltic contractions. Imperforate anus is another, unrelated congenital bowel condition in which no complete separation of tissues occurs to allow formation of an anal opening.

Front 308

The first human cancer that has been strongly linked to a virus is1. Hodgkin's disease.2. multiple myeloma.3. Burkitt's lymphoma.4. acute lymphocytic leukemia.5. chronic myelogenous leukemia.

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Good WorkThe correct choice is choice 3, Burkitt's lymphoma. Burkitt's lymphoma is a B-cell tumor which is the most common neoplasm in children in regions of the world where Epstein-Barr Virus (EBV) is endemic: These regions include New Guinea and Central Africa. It is thought that concomitant infection with malaria or another infectious agent in a host who has mononucleosis from EBV renders this host susceptible to developing Burkitt's lymphoma. This is a consequence of the immunosuppressive effect of malaria or some other agent. Immunosuppression prevents the host from clearing the Epstein-Barr virus infection. This DNA virus of the herpes family can then cause clonal expansion of B-cells as it replicates unhindered. Clonal expansion leads to an increased likelihood of producing a malignant strain of B-cells through random mutation. The mutation which most commonly gives rise to Burkitt's lymphoma involves the translocation of genes from chromosome 8 to chromosome 14. Other viruses which have been linked to human cancers include the human immunodeficiency virus which is associated with Kaposi's sarcoma, hepatitis B virus which may cause hepatocellular carcinoma, and herpes simplex I1 which may play an etiologic role in the development of cervical carcinoma. Human tumors of the lymphoid system other than Burkitt's lymphoma, such as Hodgkin's disease, multiple myeloma, acute lymphocytic leukemia, and chronic myelogenous leukemia have not been firmly linked to any specific viruses. In animals, however, many viruses have been discovered which produce lymphomas and leukemias. Examples include the gross leukemia virus which causes leukemia in mice and the feline leukemia virus which causes cancer in millions of domesticated cats each year. Once again, the correct choice to question is answer #3.

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The immediate type of hypersensitivity in which histamine does NOT play a major role is1. asthma.2. urticaria.3. anaphylaxis.4. Arthus reaction.

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Good WorkThe correct answer is choice 4. Asthma, choice 1, is a type 1 IgE mediated hypersensitivity reaction. It involves histamine and leads to airway resistance, labored breathing and hypoxia. Urticaria, choice 2, is a rash or hives which accompanies IgE mediated hypersensitivity reactions. So histamine is again involved. Choice 3, anaphylaxis, is an acute type 1 hypersensitivity reaction involving IgE and histamine especially from a second exposure to an antigen. Choice 4, Arthus reaction refers to a hypersensitivity reaction caused by large numbers of antibody antigen complexes that fix complement, attract PMNs, and are phagocytized by them. The PMNs release lysosomal enzymes which can damage tissue. Histamine does not play a major role in this Arthus reaction. An example of an Anhus reaction is serum sickness. So the correct answer to question is choice 4.

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The indiscriminate use of broad-spectrum antibiotics is contraindicated because they frequently1. are extremely nephrotoxic.2. cause psychogenic symptoms.3. produce dependency reactions.4. induce anaphylactoid reactions.5. interfere with indigenous biota.

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Good WorkThe correct choice is choice 5. interfere with indigenous biota. Broad spectrum antibiotics should be used with extreme caution. Their utilization leads to the eradication of the normal flora colonizing many sites throughout the body. This is dangerous because the normal flora serves an important function. It holds the growth of organisms resinant to antibiotics in check. When the normal flora is cleared, these resistant organisms can replicate freely as competition for nutrients decreases. Many of these resistant organisms, particularly Pseudomonas, E. coli and Klebsiella species, cause sepsis which can only be treated with newer, more powerful antimicrobial agents. These agents select for resistant strains for which no antibiotic treatment is available. Some antibiotics such as the aminoglycosides are extremely nephrotoxic as stated in choice 1. Signs of nephrotoxicity should be monitored when utilizing these drugs, but fear of inducing nephrotoxicity should not inhibit the physician from using them when indicated. Psychogenic symptoms, choice 2, and dependency reactions, choice 3, are not problematic in antimicrobial therapy. Choice 4, anaphylaxis, does occur, however. It can occur with any drug, but is most common with the penicillins and cephalosporins. As with nephrotoxicity, the spread of anaphylaxis should not deter the physician when antibiotic treatment is indicated unless the patient has had a previous episode of anaphylaxis or allergy to the drug of choice. Once again, the correct choice to question is choice 5.

Front 311

The likelihood that oral bacteria play an important role in gingival inflammation is evidenced by1. an increase in salivary hyaluronidase.2. an increased number of bacteria in saliva.3. an increase in bacterial antibodies in saliva.4. appearance of new pathogenic strains in the affected area.5. a reduction in inflammation by removal of bacteria.

Back 311

Good WorkThe correct answer is choice 5. Among the basic demonstrations that bacteria are involved in gingival inflammation would be that the bacteria are present when the inflammation occurs, that the inflammation would be greater with greater amounts of bacteria, and that the removal of the bacteria should reduce the inflammation. Therefore, choice 5 is logical and is our correct answer. Choice 1 is incorrect. Hyaluronidases are produced by bacteria to hydrolyze hyaluronic acid ground substance of connective tissue. Finding large amounts in the saliva might indicate increased bacterial numbers in the oral cavity, but not that these bacteria cause gingivitis. Likewise, choice 2 is incorrect for a similar reason. Increased number of bacteria in saliva does not show that these bacteria are rehponsible for gingival inflammation or caries or halitosis or anything else, only that their numbers are higher. Similarly, choice 3 is incorrect as increased antibodies probably show only increased numbers of bacteria which we already rejected as answer choice 2. Choice 4 is close but not good enough. While a change in bacterial types during inflammation might give some indication that the bacteria are involved, it is not as direct evidence as that shown in choice 5, where removing the bacteria reduces the inflammation. For example, the change in the bacteria strain might be a result of the gingival inflammation and not a cause of it. So the correct answer to question is choice 5.

Front 312

The likelihood that oral bacteria play an important role in gingival inflammation is evidenced by which of the following?A. An increase in salivary hyaluronidaseB. An increased number of bacteria in salivaC. An increase of neutralizing antibodies in salivaD. A reduction of inflammation with reduction of plaque

Back 312

Good WorkThe correct answer is choice D. Evidence that a certain condition is associated with a certain microorganism should include some or all of the conditions of Koch's postulates. For example, the organism should be present when the condition is present, it should be absent when the condition is absent, the condition should be worse when more of the organism is present, and improve when the organism is removed. This is consistent with choice D. Hyaluronidase is not a normal constituent of saliva. Increased numbers of bacteria in saliva may show something about the condition of the saliva, soft tissues, teeth, salivary glands or many other conditions. It would not necessarily show anything about the gingiva specifically. A similar argument holds for antibodies in saliva, as they would not be specifically connected to anything occurring within the gingiva. So the correct answer to question is choice D.

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The majority of cases of pharyngitis are caused byA. alpha-hemolytic streptococci.B. Staphylococcus aureus.C. a variety of viruses.D. herpes simplex virus.E. hemophilus influenzae.

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Good WorkThe correct answer is choice C. The majority of cases of pharnygitis are caused by a variety of viruses eg. picornaviruses. orthomyxoviruses, Epstein-Barr, etc ... Choice A - is incorrect - alpha-hemolytic streptococci is the most common cause of bacterial pneumonia, and also causes otitis media, sinusitis, bronchitis, and bacteremia. It is the most common cause of meningitis in the elderly. Choice B - is incorrect - Staphylococcus aureus causes skin infections, (eg. cellulitis) deep infections (e-g. bone), systemic infections secondary to deep infections, and toxin mediated disease (eg toxic shock syndrome). Choice D - is incorrect - Herpes simplex virus causes oral and genital lesions by infecting epithelial cells. Upon resolution of acute illness, latent infections are commonly found in neurons. Choice E - is incorrect - Hemophilus influenzae causes meningitis, otitis media, and epiglottis. Primarily children under the age of five are affected. Therefore the correct answer to question is C.

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The most characteristic finding in intestinal malabsorption syndrome is1. pain.2. melena.3. anorexia.4. diarrhea.5. steatorrhea.

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Good WorkThe correct choice is choice 5, steatorrhea. Intestinal malabsorption can result from a wide variety of causes. The intestinal mucosa may be defective, such as in intestinal lymphoma or Crohn's disease, or it may be covered by bacteria such as in bacterial overgrowth syndrome. Alternatively, organs participating in digestion may be defective. The pancreas does not secrete normal amounts of digestive enzymes in pancreatitis or cystic fibrosis. In choledocholithiasis, the gall bladder cannot secrete bile salts into the intestine due to obstruction of the common bile duct. In hepatitis, synthesis of bile salts is impaired. Whatever the cause of malabsorption, steatorrhea often results. Steatorrhea literally means "fatty stool." Fat which is not absorbed gets passed in the feces. The stool floats and has a greasy appearance. Pain, choice 1, may be associated with malabsorption when the disease causing malabsorption also causes pain. Crohn's disease, for example, is especially painful. However, many malabsorption syndromes are not painful. Melena, choice 2, is the passage of black stool. The stool is black due to the presence of digested blood. Melena is the marker of an upper GI bleed. It is not associated with malabsorption. Anorexia, choice 3, is not commonly seen in malabsorption. In fact, individuals with malabsorption may exhibit hyperphagia as they are nutritionally deprived secondary to a poorly functioning gut. Diarrhea, choice 4, occurs when the malabsorption syndrome involves the large bowel or when malabsorption is secondary to increased transport of food through the gastrointestinal tract. However, many malabsorption syndromes are not characterized by diarrhea. In addition to steatorrhea, other common symptoms in malabsorption include wasting, weakness, tetany and easy bruisability. Once again, the correct choice to question is choice 5.

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The most common cause of a massive hematemesis in alcoholics is1. peptic ulcer.2. acute gastritis.3. esophageal varices.4. Mallory-Weiss syndrome.5. acute hemorrhagic pancreatitis.

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Good WorkThe correct answer is choice 3. Esophageal varices are commonly found in alcoholics. They are large, swollen veins in the esophagus which are easily and often ruptured, leading to massive bleeding or hematemesis. The varices are due to poor portal circulation due to cirrhotic liver damage, followed by drainage of the portal blood through coronary veins of the stomach and the esophageal veins. Choice 1, peptic ulcer, may cause bleeding, but not usually of a massive type and it is not strongly associated with alcoholic patients. Likewise, acute gastritis, choice 2, may be related to alcohol, but has many other etiologies including aspirin, smoking and stress. It is also less likely to lead to massive bleeding. Choice 4 is close to correct. Mallory-Weiss syndrome refers to small tears in the gstroesophageal junction secondary to recurrent forceful vomiting. Although it is often found in alcoholics and can lead to hematemesie, it is not as common among alcoholics as are esophageal varices, the correct choice. Choice 5, acute hemorrhagic pancreatitis, refers to release of enzymes within the pancreas and is common in alcoholics. It often results in severe pain, vomiting and fever, but not usually in hematemesis. So the correct answer to question is choice 3.

Front 316

The most common clinical consequence of benign prostatic hyperplasia is1. pain.2. jaundice.3. urinary tract obstruction.4. red blood cell casts in urine.5. progression to prostatic carcinoma.

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Good WorkThe correct answer is choice 3. Benign prostatic hyperplasia involves nodular growth within the prostate which usually leads to urinary tract obstruction, which is choice 3. It is currently believed that benign hyperplasia does not predispose the individual to prostatic carcinoma, so choice 5 is incorrect. Choice 1 is incorrect. Many cases of prostatic hyperplasia are asymptomatic. Choice 2 is incorrect as there is no connection between the prostatic hyperplasia and jaundice, which is a general skin discoloration usually associated with liver dysfunction and excess bilirubin. Choice 4 is incorrect as red cell casts in the urine are not associated with prostatic hypertrophy. So the correct answer to question is choice 3.

Front 317

The rickettsial disease that may have oral manifestations isNBDE Part I released questions - Microbiology-PathologyThe rickettsial disease that may have oral manifestations is1. rickettsialpox2. Brill's disease.3. epidemic typhus.4. none of these.

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Good WorkThe correct answer is choice 1. Rickettsia are gram negative coccobacilli and are most famous for causing rocky mountain spotted fever and typhus. Our correct answer, choice 1, rickettsial pox is spread by mites on house mice. Clinically, it involves a vesicular papular rash which may spread to the lips and buccal mucosa. Lymphadenopathy is another common clinical sign. Choice 2, Brill's disease, is a disease found in patients who formerly had epidemic typhus. It is milder without skin rash and does not have any oral symptoms. Choice 3. epidemic typhus, is spread by the human body louse and signs and symptoms include fever, chills, myalgia and headache followed hy cutaneous erythema but it does not spread orally. So the correct answer to question is choice 1.

Front 318

The renal lesion most commonly associated with benign hypertension is1. renal atresia.2. acute pyelonephritis.3. chronic pyelonephritis.4. arteriolonephrosclerosis

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Good WorkThe correct answer is choice 4. Arterionephrosclerosis refers to thickening or hyalinization of renal arterioles. It is caused by mild hypertension and does not normally impair renal function. Renal atresia, choice 1, refers to a congenital absence or closure of arteries to a kidney. Choice 2 and 3, pyelonephritis, refers to infection of the renal pelvis, tubules or interstitium often from gram- negative bacteria from the patient's fecal flora. In chronic pyelonephritis, some scarring may occur and may be associated with hypertension. However, the association of arterionephrosclerosis and benign hypertension is much closer, so the correct answer to question is choice 4.

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The principal antibacterial action of the tetracyclines is inhibition of1. DNA synthesis.2. protein synthesis.3. histone formation.4. cell wall synthesis.5. cell membrane function.

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Good WorkThe correct answer is choice 2. Tetracyclines act by inhibiting binding of the aminoacyl-tRNA to the 30S subunit of the bacterial ribosome. Thus, protein synthesis is prevented. Tetracycline has no other effects listed in choices 1, 3, 4 and 5. However, as typical examples, penicillins prevent cell wall synthesis, choice 4, as do cephalosporins. Erythromycins interfere with protein synthesis as do clindamycin and lincomycin. Polymyxins coat bacterial cell membranes and destroy active transport, choice 5. Some antiviral drugs, such as acyclovir, can interfere with DNA replication, choice 1. Anyway, the correct answer to question is choice 2.

Front 320

The primary sources of pathogenic microorganisms in the dental operatory are1. light handles.2. dust particles.3. patients' charts.4. the mouths of patients.5. the hands of clinicians.

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Good WorkThe correct answer is choice 4. In this question, there are a number of possible sources of pathogenic organisms. However, one is by far the greatest source, the human mouth. A large variety of bacteria, viruses, fungi and other microorganisms exist in the human mouth within the saliva, on teeth surfaces or within the blood or mucosa. They could include Staphylococci, spirochetes, hepatitis-B virus and many others. Choice 1 is incorrect. While some pathogens from a patient might survive temporarily on a light handle, it would not be a primary source of pathogens. The same argument holds for Choice 3, patient's charts. However, it is even less likely that many pathogens will survive for very long on a chart. Choice 2 is incorrect. Few if any human pathogens are found on dust particles. Choice 5 is incorrect. Some pathogens could be found on a clinician's hands if they are not washed and gloved between patients. However, the source of the pathogens is likely to be a patient's mouth. So we are back again to choice 4, the correct answer to question.

Front 321

The oral vesicular lesions of herpangina and hand-foot-and-mouth disease are caused by1. coxsackievirus.2. Epstein-Barr virus.3. herpes simplex type I.4. varicella-zoster virus.5. respiratory syncytial virus.

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Good WorkThe correct answer is choice 1. Herpangina is a disease caused by coxsackievirus . It is a self limited disease and involves abrupt onset of fever, sore throat and anorexia. Hand, foot and mouth disease is caused by coxsackievirus as well and involves ulcerations of the mouth and pharynx and rash of the hands, arms, feet and legs. Epstein Barr virus, choice 2, is a causative agent of infectious mononucleosis and is also associated with development of Burkitt's lymphoma. Herpes simplex type 1 is a causative agent for herpes labialis as well as acute herpetic gingivostomatitis, keratoconjunctivitis and a form of encephalitis. Varicella zoster virus, choice 4, is a causative agent of varicella, or chicken pox and also zoster or shingles. Respiratory syncytial virus, choice 5, is the causative agent of respiratory infections, especially of the upper respiratory tract. So the correct answer to question is choice 1.

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The most likely source of bacteria found in diseased periodontal tissue is1. serum.2. saliva.3. subgingival plaque.4. supragingival plaque.

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Good WorkThe correct answer is choice 3. It is widely accepted that the major cause of periodontal disease and tissue destruction is the bacteria found in subgingival plaque and calculus. The bacteria in subgingival plaque can become incorporated in the calcified plaque known as calculus and cause destruction of the periodontal ligament and surrounding bone. Choice 1 , serum, is incorrect. Serum refers to blood plasma minus fibrinogen-clotting protein. Serum would not normally contain any bacteria as it is generally sterile except during cases of a bacteremia where bacteria may enter the body and temporarily travel through the bloodstream. Choice 2 is incorrect. While some bacteria exist in saliva, they are usually derived from the bacteria present on teeth and mucosal surfaces andlor bacteria ingested with food. Large numbers of bacteria and saliva do not normally enter the periodontia. Choice 4 is incorrect. Supragingival plaque, plaque formed above the gumline, is generally of a different composition than subgingival and does not lead to subgingival calculus formation and periodontal destruction. It is often involved in caries formation however. So the correct answer to question is choice 3.

Front 323

The most likely diagnosis for a patient with dysphonia, dysphagia, weight loss and a history of heavy cigarette smoking is1. laryngitis2. tonsillitis.3. laryngeal polyps.4. carcinoma of the lungs.5. carcinoma of the larynx.

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Good WorkThe correct answer is choice 5. Dysphonia refers to difficulty in producing sounds and indicates involvement of the vocal cords or larynx. Dysphagia refers to difficulty in swallowing. The accompanying weight loss and history of cigarette smoking are a both suggestive of the presence of a cancer of the respiratory tract. However, the dysphonia suggests cancer of the larynx and not the lungs. Choices 1 and 2, laryngitis and tonsillitis are both inflammatory processes. However, they are not necessarily associated with weight loss and history of heavy cigarette smoking. While they might be part of a differential diagnosis, a carcinoma should be suspected first. Tonsillitis would also be likely to be accompanied by fever. Choice 3, laryngeal polyps, are inflammatory overgrowths due to chronic irritation, but would not be associated with dysphagia or weight loss, and do not progress to malignancy. So the correct answer to question is choice 5.

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The MOST important viral cause of gastroenteritis in children less than 2 years old isA. rotavirusB. echovirusC. rhinovirusD. coxsackievirusE. cytomegalovirus

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Good WorkThe correct answer is choice A. Rotavirus is the major viral cause of gastroenteritis in children less than 2 years old. The disease is seasonal and classically occurs in the fall and winter months. Choice B - Echovirus presents clinically as aseptic meningitis, fever, rash, enteritis, common colds and/or acute hemorrhagic conjunctivitis. Less common symptoms include paralysis, pleurodynia, encephalitis, myocarditis, and respirtory illness. Choice C - Rhinovirus is most commonly associated with the common cold. Clinical manifestations include upper respiaratory tract irritation, headache, nasal discharge, cough, malaise, chills, and myalgia. Choice D - Coxsackievirus Type A may cause herpangina, with headache, sore throat, dysphasia, stiff neck, fever, anorexia, and abdominal pain. Discrete vesicles are seen in the oropharynx. It is also the etiologic agent of hand-foot-and-mouth disease. Type B may cause myocarditis, pericarditis, and pleurodynia. Both types may cause meningitis in humans. Choice E - Cytomegalovirus elicits a mononucleosis illness including fatigue, malaise, tender lymphadenopathy, pharyngitis, fever, headache, and splenomegaly. The majority of these infections are subclinical (with no overt symptoms) but may lead to life-long latent infection. In immunosuppressed patients infection is more severe and marked by fever, adenopathy, leukopenia, hepatosplenomegaly, and myalgias. Therefore the correct answer to question is A.

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The MOST important characteristic of malignant neoplasms, which distinguishes them from benign neoplasms, is theirA. nonencapsulation.B. rapid growth rate.C. ability to metastasize.D. lack of differentiation.E. excessive mitotic activity.

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Good WorkThe correct answer is choice C. All of the factors listed are related to tumor growth. Benign tumors tend to be defined in shape and capsulated. By contrast, malignant growths are more formless without distinct boundaries. Both benign and malignant tumors may have a fast rate of growth, although benign tumors usually grow slower. Malignant growths, in general, show a lack of differentiation. The cells in the neoplasm do not form well-specialized tissues. Excessive mitotic activity is associated with neoplasms in general. The rapid growth of undifferentiated tissue requires cell mitosis. However, mitotic rate is much greater in the malignant growth as compared to that in the benign neoplasm. The major difference between benign and malignant tumors and the most important to the prognosis for the patient is the ability of the malignant tumor to spread (metastasize) to other parts of the body through blood or lymph channels. As a result, secondary tumors will grow, which makes the prognosis for the patient inevitably worse. So the correct answer to question is choice C.

Front 326

The most frequent complication following a single transfusion of blood that was inadequately cross matched is1. leukopenia.2. infectious hepatitis.3. altered clotting time.4. agglutination of the recipient's erythrocytes.5. agglutination of the donor's erythrocytes.

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Good WorkThe correct choice is choice 5, agglutination of the donor's erythrocytes. Fatal transfusion reactions most commonly occur when a clerical error is made and blood is given to the wrong patient. On rare occasions, the blood is inadequately cross-matched and the recipient possesses undetected antibodies directed against antigens on the donor's red blood cells which are capable of causing agglutination of donor cells. Agglutination activates complement and hemolysis results. The patient may then progress to acute renal failure which is often irreversible. Leukopenia, choice 1, does not occur in transfusion reactions. Infectious hepatitis, choice 2, is a very common complication of transfusion. Non-A/non-B hepatitis is transmitted through transfusion and 5-10% of transfused individuals will become infected. Transfusion hepatitis, however, cannot be prevented by cross-matching procedures. Improperly and properly cross-matched blood carry the same risk of hepatitis transmission. Altered clotting time, choice 3, is a late manifestation of some severe transfusion reactions. It results when the patient develops disseminated intravascular coagulopathy and is a pre-terminal event. An altered clotting time may also accompany transfusion hepatitis, but as mentioned, hepatitis does not result from improper cross-matching. Agglutination of recipient's erythrocytes, choice 4, does not occur to a significant extent when packed red blood cells are given. Packed red blood cells contain little or no donor antibody. Agglutination of recipient cells may occur, however, when inadequately cross-matched plasma is given and donor antibodies against recipient red blood cells are introduced. Once again, the correct choice to question is choice 5.

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The most common type of epithelial metaplasia involves1. regeneration of epithelium in an area of cutaneous ulceration.2. replacement of squamous cells by cuboidal cells.3. replacement of cuboidal cells by columnar cells.4. replacement of columnar cells by stratified squamous epithelium.

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Good WorkThe correct answer is choice 4. Metaplasia involves the abnormal replacement of one type of normal cell or tissue by a different type of normal cell or tissue. In this case, choice 1 is incorrect as it does not involve replacement of one normal tissue by a different one. However, choices 2, 3 and 4 all look possible. Choice 4 is correct because it occurs fairly commonly. Ciliated columnar epithelial cells in the trachea can become damaged by smoke or other chemicals and often, the extended chronic exposure to the irritant will cause the tracheal lining to become squamous rather than ciliated columnar. So the correct answer to question is choice 4.

Front 328

The most common primary bronchogenic carcinoma is the:A. small cell carcinomaB. large cell carcinomaC. squamous cell carcinomaD. adenocarcinomaE. oat cell carcinoma

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Good WorkThe correct answer is choice C. The squamous cell carcinoma composes approximately 35-50% of primary bronchogenic carcinomas. It is highly correlated with smoking, metastasizes later than other types, but grows larger in its primary area. Second and third in frequency (depending on report) are the small cell carcinoma (choice A) and adenocarcinoma (choice D). Note that the small cell is also known as oat cell (choice E) due to the small cell appearance with prominent nucleus and little cytoplasm. These are aggressive tumors and very malignant. They often secrete hormones and cause paraneoplastic syndromes. Large cell carcinomas (choice B) are the rarest (approximately 10%) but have a very poor prognosis.

Front 329

The most common malignant neoplasm of the stomach is:A. leiomyomaB. gastric polypsC. sarcomaD. carcinomaE. Krukenberg tumor

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Good WorkThe correct answer is choice D. Benign neoplasms of the stomach include leiomyoma (choice A), a benign muscle tumor, and gastric polyps (choice B), which are outgrowths of gastric mucosa. Adenomatous type polyps have high malignant potential, however. Carcinoma is the most common malignant tumor of the stomach. Histologically, they are composed of gastric and intestinal mucus-secreting cells. Prognosis for the condition is poor due to the late occurrence of symptoms. Carcinoma of the stomach spreads through the lymphatics. Sarcoma of the stomach (choice C) is rare. Carcinoma of the stomach can metastasize to the ovary and form the Krukenberg tumor (choice E).

Front 330

Which chemical substance is usually secreted by pheochromocytomas?A. CatecholamineB. AldosteroneC. CortisoneD. InsulinE. Renin

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Good WorkThe correct answer is choice A. A pheochromocytoma is a tumor which produces catecholamines (epinephrine and norepinephrine). This is due to the fact that the tumor is found in the adrenal medulla, which normally produces these compounds. None of the other hormones listed are from the adrenal medulla. Note that the oversecretion of catecholamines results in severe hypertension. So the correct answer to question is choice A.

Front 331

Which acidogenic bacteria often causes significant dental decay in deep established dental caries?A. BacteroidesB. Strep. mitisC. LactobacillusD. ActinomycesE. Strep. sanguis

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Good WorkThe correct answer is choice C. Lactobacillus is an aciduric bacteria which produces lactic acid as a metabolic waste product. It lowers the pH in the immediate environment to the extent that most other bacterial species cannot survive. It is considered to be a late colonizer of carious lesions which are initiated and also continued by aciduric Strep. mutans. In particular, Lactobacillus is found deep within the lesion. Bacteroides is an anaerobe found in the gingival sulcus and asssociated with chronic adult periodontitis (especially B. melaninogenicus). Strep. mitis, Strep salivanus and Strep. sanguis are all Viridans streptococci, and are common oral flora. Actinomyces are also common oral flora. They are gram-positive rods which can cause infections of oral tissue. A characteristic lesion will form in the mouth and drain to the face. Material which resembles "sulfur granules" (but is not!) is found in the exudate from these fistulas.

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When one cell type or tissue is replaced by another type that is not normally located at that place, this process is known as:A. carcinoma in situB. anaplasiaC. metaplasiaD. dysplasiaE. hyperplasia

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Good WorkThe correct answer is choice C. In metaplasia, changes in conditions or local environment cause the change of one tissue type to another. In smokers, a common metaplasia occurs in bronchi and trachea, where the normal pseudostratified ciliated columnar epithelium is replaced by nonciliated stratified squamous epithelium. This is sometimes viewed as a precursor to cancer development. Anaplasia (choice B) refers to loss of cell differentiation. Dysplasia (choice D) refers to abnormal cell proliferation. Hyperplasia (choice E) refers to growth of a large number of cells; however, the cells are generally normal. Carcinoma in situ (choice A) is an epithelial cancer that has not yet invaded connective tissue and resides completely above the basal lamina.

Front 333

Viral species can be partially identified through the use of any of the following characteristics EXCEPT:A. ability to pass through filter poresB. susceptibility to etherC. type of genome materialD. microscopic appearanceE. ability to grow on various media

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Good WorkThe correct answer is choice E. As obligate intracellular parasites, viruses must be grown in cell culture and cannot be grown on media. They can be partially identified by filtration (gives size estimate), appearance under electron microscope, whether they contain RNA or DNA (nucleic acid identification), and sensitivity to solvents and chemicals (especially ether). Naked viruses often are more resistant to ether, whereas enveloped viruses are more susceptible to ether damage.

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Vancomycin is an antiinfective agent indicated for the treatment of potentially life threatening infections caused by gram positive bacteria. Vancomycin would most likely be used to treat an infection caused byA. Candida albicansB. Enterococcus faeciumC. Escherichia coliD. Klebsiella spp.E. Pseudomonas aeruginosa

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Good WorkThe correct answer is B. Vancomycin is an antiinfective agent indicated for the treatment of potentially life threatening infections caused by gram positive bacteria, especially gram positive cocci. This agent is primarily used to treat infections caused by Enterococci (Enterococcus faecium) (choice B), streptococci, and staphylococci, including methiciilin resistant staphylococci. Candida albicans (choice A) is a fungus and is frequently the causative organism in vaginal yeast infections and oral thrush. Since Escherichia coli (choice C), klebsiella (choice D) and Pseudomonas aeruginosa (choice E) are gram-negative organisms, this agent would be ineffective in the treatment of infections caused by these bacteria.

Front 335

Use of vaccines for preventing clinical symptoms after introduction of the virus is most likely to be effective against1. rabies.2. influenza.3. poliomyelitis.4. herpes zoster.

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Good WorkThe correct answer is choice 1. Rabies is an acute viral infection of the central nervous system. Rabies virus remains latent in tissues for some time after the virus is introduced from a bite. Therefore, a vaccine can be administered and antibodies will form before the virus invades the CNS or central nervous system. In most cases, passively administered antibodies are also introduced. These antibodies, produced from, human or equine blood, provide additional time for the vaccine to stimulate active antibody production before the CNS is invaded. This type of post-infection vaccination is not possible against influenza, polio or herpes zoster because the viruses do not have the long latent period mentioned previously for rabies virus. So the correct answer to question is choice 1.

Front 336

Two important factors for initiation of caries by oral streptococci are1. production of protease and production of acid.2. production of dextranase and production of soluble dextran.3. production of collagenase and production of hyaluronidase.4. fermentation of mannitol and sorbitol and production of protease.5. synthesis of insoluble dextran and production of glucosyltransferase.

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Good WorkThe correct choice is 5, synthesis of insoluble dextran and production of glycosyl transferase. Of the Streptococci which colonize the oral mucosa, Strep. mutans has been most consistently correlated with the development of dental caries. This organism is an effective pathogen due to its unique capacity to bind to teeth. This is accomplished with the use of glycosyl transferase, an enzyme projecting from the outer membrane of the bacteria. Glycosyl transferase polymerizes the glucose moiety from sucrose to form dextran. Dextran is an insoluble adherent substance which promotes the accumulation of bacteria on the tooth enamel. This substance also prevents the diffusion of organic acids produced by the bacteria. As a consequence, protons accumulate in the dextran bacteria mass, also called plaque, and the pH of the environment decreases. The acid erodes the tooth enamel and caries result. Choice 1 is incorrect because proteases are not involved in this process. Proteases are enzymes which degrade proteins. Tooth enamel is primarily mineral with little protein content. Choice 2 is the wrong answer because, as mentioned, dextran is insoluble. Dextranase, an enzyme which degrades dextran, would impede the development of caries, not promote it, as dextran plays a fundamental role in the pathogenesis of caries. Collagenase and hyaluronidase, enzymes referred to choice 3, degrade collagen and hyaluronic acid, respectively. These substances are components of connective tissue, not tooth enamel. Consequently, these enzymes bear no relevance to this discussion. Choice 4 is incorrect for the same reason choice 1 is incorrect; namely, proteases play no role in the development of caries. Streptococci derive their energy from the fermentation of sugars to produce lactic acid and ATP. They may possess a capacity to ferment mannitol and sorbitol as stated in choice 4, but this capacity is important only in the identification of these organisms, not in understanding their pathogenicity. Once again, the correct answer for question is choice 5.

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The term "biofilm" as it applies in dentistry is most often used to describe:A. A safer type of x-ray filmB. A detector that protects tissue from x-ray damageC. The surface of dentin inside a cavity preparationD. The surface of dental waterlinesE. None of the above

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Good WorkThe correct answer is choice D. The problem of bacteria in dental waterlines is probably going to be the next intensive infection control issue faced by dentistry. The narrow bore of most dental waterlines encourages a thin film colony of bacterial slime (biofilm) to form on the inner circumference of the waterline. Water entering the dental unit, although chlorinated at the source, is clean, but not sterile. The microorganisms it contains can form extensive colonies inside the tubes. While no specific disease cases have been linked to these microorganisms, it is clear that they should be minimized. Several systems of filtration or chemical disinfection are now available. Other alternatives include bottled irrigation water and flushing the lines for several minutes several times each day.

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Which of the following describes the function of adjuvants?A. Enhance secretion of IgAB. Enhance antibody responseC. Stimulate complement synthesisD. Desensitize to a given antigenE. Activate mast cell degranulation

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Good WorkThe correct answer is choice B. Adjuvants are chemicals, usually proteins, which enhance immune response. For example, if you wish to induce delayed hypersensitivity in an experimental animal, a protein antigen is mixed with an adjuvant to obtain a greater response. The adjuvant is sometimes dead tubercle bacilli in oil, or another organism, such as Nocardia. Research is taking place to identify safe adjuvants for use in humans, for example, to increase immune response against tumors. So the correct answer to question is choice B.

Front 339

Which of the following conditions results in the development of a normocytic, normochromic anemia?A. Acute blood lossB. Folic acid deficiencyC. Iron deficiencyD. Sickle cell diseaseE. Thalassemia

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Good WorkAnemias are often classified according to the morphology of the red blood cell as well as the etiology of the anemia. With respect to the morphologic classification of red blood cells, "cytic" refers to the size of the red blood cell and chromic refers to the color. For example, acute blood loss (choice A) will typically result in a normocytic, normochromic anemia. In other words, the red blood cells are all "normal"; however, there are not enough of them to meet the needs of the body. Folic acid (choice B) and vitamin B12 deficiency will lead to the development of a macrocytic, normochromic anemia. In a microcytic, hypochromic anemia, the red blood cell is smaller than normal and is lacking color. This type of anemia typically results from an iron deficiency (choice C). As mentioned before anemias can also be classified by their etiology. The major causes of these types of anemias are increased blood cell loss and decreased or defective red blood cell production. For example, sickle cell disease (choice D) causes hemoglobinopathies with an inherited abnormal hemoglobin. Thalassemia (choice E) is caused by an impaired globin synthesis.

Front 340

Which of the following conditions predisposes to lung cancer by causing squamous metaplasia of bronchial epithelium?A. BronchiectasisB. Bronchial asthmaC. Chronic bronchitisD. Bronchial carcinoidE. Pulmonary emphysema

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Good WorkThe correct answer is choice C. In chronic bronchitis, especially among smokers, normal bronchial epithelium of the pseudostratified ciliated columnar type may be replaced by stratified squamous. In addition to the loss of protective function of the mucus and cilia, this change is also often precancerous. Bronchiectasis is not precancerous and refers to the abnormal dilatation of the bronchi following chronic infection. Bronchial asthma is not precancerous and refers to narrowing of the bronchi and excess mucus production causing difficulty in breathing. Bronchial carcinoids are benign lesions of neuroendocrine argentaffin cells of bronchial mucosa. Pulmonary emphysema is not precancerous and involves distention of air spaces with destruction of alveoli. So the correct answer to question is choice C.

Front 341

Which of the following conditions increase the risk of developing osteosarcoma?A. OsteomalaciaB. OsteoporosisC. OsteoblastomaD. Osteitis deformansE. Osteogenesis imperfecta

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Good WorkThe correct answer is choice D. Osteitis deformans, or Paget's disease of bone is a condition of unknown origin in which bone is replaced by disorganized soft matrix. Multiple areas of soft bone, changed size and shape of bone and bone pain result. Deformity and fracture are common. About 1% transform to malignant neoplasm(osteosarcoma). All four other choices are not associated with malignant transformation. Osteomalacia is a condition of soft bones subsequent to vitamin D deficiency. There is impaired mineralization of osteoid. Osteoporosis is weakening of bones due to loss of bone mass. It is especially common in older women, and may be related to estrogen deficiency, malnutrition or immobilization. Osteoblastoma is a usually benign tumor of bone that occurs at the diaphysis of long bones. It is related to osteoid osteoma. In cases where it is malignant, it does not develop into osteosarcoma. Osteogenesis imperfecta is an inherited condition of collagen synthesis. It involves thin, fragile bones, small discolored teeth and blue sclera. So the correct answer to question is choice D.

Front 342

Which of the following characterizes victims of fatal, acute carbon monoxide poisoning?A. Cherry red bloodB. Acute renal failureC. Massive liver necrosisD. A hypercoagulability stateE. Anemia and generalized white cell depletion

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Good WorkThe correct answer is choice A. Carbon monoxide binds strongly to hemoglobin, even more strongly than oxygen does. It also bonds in a very slowly reversible way, so that hemoglobin bound to carbon monoxide stays bound for long periods of time. This hemoglobin has a distinct cherry red color. Carbon monoxide poisoning results in oxygen starvation to all tissues, but starting with such oxygen-sensitive organs as the brain. Findings include CNS hyperemia, edema, focal hemorrhages and degeneration of basal ganglia. None of the other choices listed are characteristic of acute CO poisoning. So the correct answer to question is choice A.

Front 343

Which of the following cells is responsible for secreting antibodies during an infectious process?A. LymphocytesB. MegakaryocytesC. Plasma cellsD. Polymorphonuclear neutrophilsE. Prostaglandins

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Good WorkThe correct answer is C. Lymphocytes are the immature cells that become plasma cells (choice A). Lymphocytes, known as B cells, are responsible for humoral immunity. These activated B cells differentiate into plasma cells (choice C), which are tissue cells that secrete antibodies to attack alien cells. Megakaryocytes (choice B) are the immature cells that become platelets, which clump together and stick to vessel walls following a traumatic event. Neutrophils (polymorphonuclear neutrophils) (choice D) and macrophages are cells of the immune system that "ingest" foreign particles by flowing their cytoplasm around the foreign object. The object is then internalized in the phagosome, which is an internal envelope of cell membrane. Finally, the digestive enzymes of the lysosomes are released into the phagosome to destroyldigest the foreign object. Prostaglandins (choice E) are produced in most tissues in the body and are responsible for coordinating local cellular activities.

Front 344

Which of the following cells are increased in number in the bloodstream in allergy or parasitic infection?1. Basophils2. Eosinophils3. Plasma cells4. Atypical lymphocytes5. Nucleated erythrocytes

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Good WorkThe correct choice is choice 2, eosinophils. Eosinophils are elevated in the peripheral bloodstream in drug reactions and in five categories of diseases: neoplasm, allergy, atopy, collagen vascular disorders and parasitic infection. Their function is to limit the cascade of events initiated by the degranulation of mast cells and basophils. They also can secrete compounds which are toxic to cell membranes of parasites. Basophils, choice 1, are increased in polycythemia vera, myelofibrosis, and chronic myelogenous leukemia. Plasma cells, choice 3, are not found in the peripheral blood. Their numbers are increased in the bone marrow, however, in multiple myeloma. Atypical lymphocytes, choice 4, are present in high numbers in the peripheral blood in leukemias and in mononucleosis. Nucleated erythrocytes, choice 5. are present peripherally when erythropoiesis is accelerated. This occurs in acute hemolysis or hemorrhage. Once again, the correct choice to question is choice 2.

Front 345

Which of the following bacteria has the highest lipid content in the cell wall?1. Escherichia coli2. Lactobacillus casei3. Leptotrichia buccalis4. Staphylococcus aureus5. Mycobacterium tuberculosis

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Good WorkThe correct answer is choice 5. The Mycobacteria are rod-shaped, non-spore forming, aerobic bacteria. They are difficult to stain, but once stained, they resist decolorizing and so are known as the acid-fast bacilli. They include Mycobacterium tuberculosis, which causes tuberculosis. The cell walls of Mycobacteria are especially rich in lipids, including fatty acids and waxes. Choice 1 is incorrect. Escherichia coli is a member of the normal flora of the intestinal tract and is a gram-negative rod. Choice 2 is incorrect. Lactobacillus casei is a gram-positive rod, also a member of the normal intestinal flora. Choice 3 is incorrect. Leptotrichia buccalis is a spirochete. Choice 4 is incorrect. Staphylococcus aureus is a gram-positive coccus and a member of the skin flora. So the correct answer to question is choice 5.

Front 346

Which of the following are most characteristic of cervicofacial actinomycosis?1. Multiple ulcers2. Enlarged cervical lymph nodes3. Multiple cutaneous abscesses with sinuses4. Indurated nodules in the skin of the neck

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Good WorkThe correct answer is choice 3. Cervicofacial actinomycosis is caused primarily by Actinomyces israeli, an actinomycete. These are non spore forming, non acid fast facultative anaerobes. Actinomycosis often develops following dental caries and extractions. Multiple pyogenic abscesses develop with characteristic sinus tracts filled with yellow appearing material known clinically as "sulfur granules." Osteomyelitis can also be associated with Actinomycosis. So choice 3 is correct. Actinomycosis can spread to the thorax by extension or aspiration. Choice 1 is incorrect. Multiple abscesses, not ulcers, are common. Choice 2 is incorrect. While cervical lymph nodes may be swollen due to Actinomycosis, swollen lymph nodes would not be characteristic of the condition. Cervical lymph nodes may be swollen due to a large number of bacterial or viral conditions. Choice 4 is incorrect as indurated nodules in the neck are not common in Actinomycosis. So the correct answer to question is choice 3.

Front 347

Which of the following are MOST antigenic?A. LipidsB. HaptensC. ProteinsD. Nucleic acidsE. Carbohydrates

Back 347

Good WorkThe correct answer is choice C. Antigenic substances will produce an immune response. Proteins are, by far, the most antigenic substances. They include proteins, glycoproteins, lipoproteins and nucleoproteins. However, let's review the other choices. Lipids are not usually antigenic. Haptens are small molecules which contain antibody binding sites, but do not cause an immune response unless they are linked to a protein. In that case, two types of antibodies are formed. One binds to the protein, and the other to the hapten. Nucleic acids, like lipids, are not usually antigenic unless bound to a protein. Some large polysacharides(carbohydrates) can activate B cells, and so may be antigenic in some cases. However, proteins are the most antigenic of all molecule classes. So the correct answer to question is choice C.

Front 348

Which of the following are clinical signs/symptoms of hepatitis?A. Weight lossB. JaundiceC. HepatomegalyD. MyalgiaE. All of the above

Back 348

Good WorkThe correct answer is choice E. Hepatitis is a general term, meaning inflammation of the liver. It is often of viral origin (Hep A, B, C, D, etc.), but can have other origins such as chemical (CC14, etc.). Due to the general damaging effects to the liver, signs and symptoms are many and varied. Many can be logically predicted. They include hepatomegaly (enlarged liver), jaundice (yellow color due to back- up of bile pigments into the blood), fever, malaise, chills, nausea, myalgia (muscle pain), lymphadenopathy, darkened urine (due to increased bilirubin), weight loss, joint pain etc. Many symptoms are non-specific, and a careful history, combined with lab tests, is necessary for diagnosis.

Front 349

Which form of viral hepatitis does NOT have a carrier state?A. Hepatitis AB. Hepatitis BC. Hepatitis CD. All viral hepatitis types have carrier states

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Good WorkThe correct answer is choice A. Hepatitis A (short incubation, infectious hepatitis) does not have a carrier state. Infection by the virus induces a recovery followed by lifelong immunity. Hepatitis B (long incubation, serum hepatitis) has a carrier state and asymptomatic carriers can transmit the disease. The estimated incidence of transformation to the carrier state for hepatitis B is 5-10%. Hepatitis C (NANB) also has a carrier state, with the highest incidence of transformation to carrier estimated at 30-40%.

Front 350

Which of the following factors has the greatest impact on prognosis of a skin melanoma?NBDE Part I released questions - Microbiology-PathologyWhich of the following factors has the greatest impact on prognosis of a skin melanoma?1. Site of origin2. Depth of invasion3. Degree of pigmentation4. Existence of ulceration5. Size of surface area involved

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Good WorkThe correct answer is choice 2. Skin melanoma is a tumor of melanocytes. The most important factor in prognosis of this tumor is depth which is staged according to a Clark level 1-5, ranging from level 1, confined to the epidermis, to level 5, invading the subcutaneous fat. Site, degree of pigmentation, ulceration and surface area are all less important considerations. Melanoma is most common in the age group 40-60 and is usually treated by excision. The correct answer to question is choice 2.

Front 351

Which of the following distinguishes a viral infection from other microbial assaults?NBDE Part I released questions - Microbiology-PathologyWhich of the following distinguishes a viral infection from other microbial assaults?1. Necrosis2. Chronicity3. Interferon production4. Intracellular infection5. Need for an external vector

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Good WorkThe correct choice is choice 3, interferon production. Interferons are glycoproteins produced by cells when invaded by viruses. These glycoproteins are secreted into the medium by infected cells and they induce the synthesis of antiviral proteins in uninfected cells. The uninfected cells thereby become resistant to viral invasion and the infection caused by the virus becomes attenuated. Interferons also affect the immune system. They enhance the cytotoxicity of natural killer cells which attack virus-infected cells and they augment T-cell immunity. Interferons have also been administered therapeutically for viremias and for cancers, but have shown only limited success in treating these disorders. Necrosis, choice 1, is caused by viruses in a process called lysis. When viral particles replicate within a cell, they often cause cell death. The dead cells disintegrate and the viruses are able to spread to uninfected cells. Necrosis is not specific to virus infection, however. Many bacteria, especially the pyogenic bacteria, cause necrosis of infected tissues. Viral infections can be chronic as stated in choice 2, but so can many bacterial and fungal infections. Cryptococcal meningitis, a fungal meningitis which affects AIDS patients, is an example of a chronic fungal infection. Patients with cryptococcal meningitis may have daily headaches for months before the correct diagnosis is made. Intracellular infection, choice 4, is common among bacteria and parasites. Gonorrhea, for example, is caused by a gram-negative, intracellular diplococcus. Viruses, unlike many parasites, are not usually transmitted by vectors, and choice 5 is therefore incorrect. Viruses tend to be spread through the fecal-oral route and through aerosolization and inhalation. They are also spread by sexual contact as the AIDS epidemic clearly demonstrates. Once again, the correct choice to question is choice 3.

Front 352

Which of the following diseases is NOT associated with a species of Clostridium?NBDE Part I released questions - Microbiology-PathologyWhich of the following diseases is NOT associated with a species of Clostridium?A. Pseudomembranous colitisB. Traveler's diarrheaC. Antibiotic-associated colitis (AAC)D. BotulismE. Tetanus

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Good WorkThe correct answer is choice B. Traveler's diarrhea is usually associated with enterotoxigenic forms of Escherichia coli, which produce a peptide exotoxin. Pseudomembranous colitis (choice A) and antibiotic-associated colitis (AAC) (choice B) are caused by Clostridium dificile. AAC is a more modern term and refers to a Clostridium infection of the gut, set up by the killing of the normal gut flora by antibiotic use. The antibiotic most commonly associated with this condition is clindamycin. The most common treatment is vancomycin. Botulism (choice D) is caused by C. botulinum, often found in soil and animal feces. Damage occurs through a protein exotoxin. C. tetani causes tetanus (choice E). These organisms are also found in soil and animal feces. Damage is also caused by a protein neurotoxic exotoxin.

Front 353

Which of the following diseases is characterized by painful vesicles that occur on the skin or a mucosal surface along the distribution of a sensory nerve?1. Smallpox2. Psoriasis3. Cat-scratch fever4. Recurrent varicella4. Infectious mononucleosis

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Good WorkThe correct answer is choice 4. Recurrent varicella refers to recurrent infection by herpes virus associated with both varicella, or chicken pox, and zoster. Latent virus survive in ganglia of sensory nerves and cause mucosal outbreaks along the distribution of the nerve, often the ophthalmic division of the trigeminal nerve. Choice 1, smallpox or variola, a viral disease, will cause primarily skin lesions rather than mucosal and they are not associated with a sensory nerve distribution. Likewise, psoriasis, choice 2, usually involves skin but not mucosal membranes. The etiology of psoriasis is unknown. Choice 3, cat scratch fever, has an unknown etiology, possibly viral or bacterial, and causes fever and regional lymphadenitis, but not mucosal vesicles along a nerve distribution. Choice 5, infectious mononucleosis, is caused by Epstein-Barr virus and causes fever, enlarged lymph nodes and spleen. It is also not associated with mucosal vesicles along a nerve distribution. So the correct answer to question is choice 4.

Front 354

Which of the following diseases is associated with the "Dane Particle"?A. Hepatitis AB. Hepatitis BC. Hepatitis CD. Hepatitis DE. Hepatitis E

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Good WorkThe correct answer is choice B. A Dane particle is the name for the entire Hepatitis B virion (viral particle). It is one of three entities that will test positive as Hepatitis B surface antigens. The other two are pieces of viral coats known as spheres or filaments. Although they are not complete viral particles, they do contain the surface antigen (HBsAg). Other hepatitis B antigens include the core antigen (HBcAg) and an "e-antigen" (HBeAg). Presence of the "e-antigen" is associated with increased viral replication and infectivity of the patient.

Front 355

Which of the following forms of oral ulcerations involves oral, ocular, and genital lesions?1. Behçet's2. Herpetiform3. Recurrent aphthous4. None of these

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1. Behçet'sThe correct answer is choice 1. Behcet's disease or syndrome, is a form of vasculitis or disease of the blood vessels caused by immunologic or inflammatory etiology. In particular, it affects venules and causes ulcers of the oral cavity, eyes, genitals and sometimes the skin. Choice 2, herpetiform ulcerations are caused by forms of the herpes virus and are usually found either in the oral cavity especially when caused by herpes simplex 1 or in the genital area often caused by herpes simplex 2. There may be a conjunctivitis or inflammation of the outer covering of the eye but generally no ocular ulcerations. So choice 2 is close but incorrect. Choice 3 is incorrect. Recurrent aphthous lesions have an unknown etiology and often occur in the oral cavity. They are painful, spherical ulcers with a possible autoimmune or psychosomatic connection. They generally do not occur on either the genitals or in the eye. So the correct answer to question 66 is choice 1.

Front 356

Which of the following fungal species is NOT a dermatophyte?A. TrichophytonB. EpidermophytonC. CoccidioidesD. Microsporum

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C. CoccidioidesThe correct answer is choice C. Coccidioides is a free-living soil organism that can occasionally cause disease, especially in the immunocompromised. Other soil fungi include Aspergillus, Blastomyces, and Histoplasma. They usually cause systemic infections. The dermatophytes generally grow on skin surfaces, causing athlete's foot, ringworm, jock itch, etc. Ringworm is due to infection by Trichophyton (choice A) or Microsporum (choice D), whereas athlete's foot is usually caused by Trichophyton or Epidermophyton (choice E). The infection by these organisms is usually limited to superficial keratinized tissues.

Front 357

Which of the following genera is MOST likely involved in bacillary dysentery?A. VibrioB. ShigellaC. EntamoebaD. SalmonellaE. Escherichieae

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B. ShigellaThe correct answer is choice B. Shigella is the most likely involved in bacillary dysentery characterized by abdominal cramps and diarrhea. The feces contain blood, polymorphonuclear leukocytes, and mucus. These symptoms are important in differentiating dysentery from diarrhea which refers to watery feces, most commonly associated with increased secretion of fluid across the mucosal surfaces of the small intestine in response to a toxin or viral infection. Choice A - Vibrio typically presents with watery ("rice water") diarrhea (20 liters/day) with the loss of sodium, chloride, potassium, and bicarbonate. Other important clinical manifestations include nausea, vomiting, abdominal cramps, metabolic acidosis and hypovolemic shock. Choice C - Entamoeba is a protozoa and thus cannot specifically cause bacillary dystenery. Clinically, the disease may be mild with diarrhea, abdominal cramps nausea, vomiting, and flatulence. Note because this also causes diarrhea, it is a good trick distractor choice. Remember though the questions asks which is the most likely involved in bacillary dystenery and clearly Shigella is the most likely. Choice D - Salmonella is also a good trick distractor choice. Salmonella infections cause inflammatory diarrhea with fever and variable septicemia. In contrast to Shigella, a large inoculum (> 1 million cells) is needed to survive gastric acid and cause disease. Thus it is less likely a cause than Shigella. Choice E - Escherichieae is the most common cause of "traveler's diarrhea". There are more than 100 serotypes of Escherichieae that cause this non-inflammatry, secretory diarrhea that is similar to Vibrio, but less severe. Therefore the correct answer to question is B.

Front 358

Which of the following genera most frequently develops resistance to penicillin?1. Neisseria2. Treponema3. Actinomyces4. Streptococcus5. Staphylococcus

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5. StaphylococcusThe correct answer is choice 5. Choice 1, Neisseria, include Neisseria meningitis and Neisseria gonorrhea. Although both strains are susceptible to penicillin, some strains of N. gonorrhea, which causes gonorrhea are becoming resistant to penicillin. Choice 2. treponema, are spirochete, including Treponema pallidum which causes syphilis. Penicillin is still the drug of choice for treatment. Choice 3, Actinomyces includes Actinomyces israeli which causes actinomycosis. Penicillin is still the drug of choice for treatment. Choice 4, Streptococcus includes a wide variety of organisms including those involved in tooth decay, endocardids and pneumonia. Most Streptococci are still sensitive to penicillin. Choice 5, Staphylococci, include a large variety of organisms and can cause diseases ranging from skin infections to osteomyelitis, pneumonia and toxic shock syndrome. Many strains are resistant to penicillin and penicillinase resistant penicillins such as dicloxacillin are the drugs of choice. So the correct answer to question is choice 5.

Front 359

Which of the following histopathologic findings during necropsy suggests that the person died of, or at least had, rheumatic fever?1. Russell bodies2. Periarteritis nodosa3. Aschoff bodies in the heart muscle4. Monckeberg's sclerosis of the aorta

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3. Aschoff bodies in the heart muscleThe correct choice is choice 3, Aschoff bodies in the heart muscle. Rheumatic fever occurs when an individual produces antibodies to group A streptococci following Strep. pharyngitis. These antibodies cross-react with antigens present in a variety of tissues, including the myocardium. In the heart muscle, this immunologic damages causes a sequelae of changes. First, an exudate forms which causes separation of muscle cells. This is followed by the formation of Aschoff bodies which are collections of histiocytes surrounding a central focus of fibrinoid material. Finally, fibroblasts proliferate and a scar is formed. Russell bodies, choice 1, are eosinophilic inclusions seen in plasma cells. They are dense collections of immunoglobulins located in the endoplasmic reticulum. Periarteritis nodosa, choice 2, is not merely a finding, but a disease process. This disorder is characterized by necrosis and thrombosis of small and medium sized arteries throughout the body. Monckeberg's sclerosis, choice 4, is a disease process in which the media of large arteries becomes calcified circumferentially. This differs from atherosclerosis in which calcium is deposited in the intima. The aorta may be involved in Monckeberg's sclerosis as indicated in choice 4, but the disease more commonly affects the large arteries of the extremities. These patients are asymptomatic unless the vessels have concomitant atherosclerotic disease. Once again, the correct choice to question is choice 3.

Front 360

Which of the following is a benign lesion, most commonly found on the buccal mucosa and the dorsal surface of the tongue, and has a surface, appearance of numerous small closely packed nodular structures filled with fluid and may resemble a blister?A. HemangiomaB. LymphangiomaC. MelanomaD. NeviE. Pleomorphic adenoma

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B. LymphangiomaThe correct answer is B. A lymphangioma (choice B) is a benign lesion that is most commonly found on the buccal mucosa and the dorsal surface of the tongue. The surface appearance is one of numerous small closely packed nodular structures filled with fluid and may resemble a blister. Oral hemangiomas (choice A) are benign lesions that occur most frequently on the buccal and labial mucosa, vermilion of the lip and the tongue. They typically present as a red, smooth, protruding lesion at the tip of the tongue. Malignant melanomas can occur in any area of the oral cavity; however, they are most frequently found on the buccal gingiva and palatal tissues. Initially the lesions are slightly raised, purplish, dark brown patches several millimeters in diameter. Due to their constant rapid growth pattern, the tumor mass tends to enlarge in all directions. A prominent, ill-defined, firmly anchored lesion eventually results. The characteristic feature of this metastatic lesion is its purplish-black color. This central lesion is surrounded by an area of erythema. Nevi (choice D) are also benign lesions that may occur in any area of the oral cavity; they typically present as discrete, localized, brown-black pigmented lesions. Pleomorphic adenomas (choice E) are commonly found in the salivary glands, palate, lip and buccal glands; this type of tumor causes a firm, slow growing mass. Surgical excision of these lesions is often indicated; however, aggressive chemotherapy and/or radiation therapy is rarely needed.

Front 361

Which of the following is a characteristic of benign, as opposed to malignant, neoplasms?A. Encapsulated lesionB. Many mitosesC. Rapid growthD. Poorly differentiatedE. Frequent metastases

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A. Encapsulated lesionThe correct answer is choice A. Let's review the characteristics of neoplasm growth. In each case, the benign neoplasm characteristic will be mentioned first, and the corresponding malignant characteristic will be in parentheses. Slow growth (fast or erratic growth) (choice C), encapsulated (no encapsulation, invasive), differentiated, like tissue of origin (undifferentiated, nonspecialized) (choice D), few mitoses (many mitoses) (choice B), normal nuclear/cytoplasm ratio (high nuclear/cytoplasm ratio), expands, compresses tissue (invades tissue), and nonmetastatic (often metastatic) (choice E).

Front 362

Which of the following is a congenital condition that alters the texture of the oral and/or vaginal mucosa causing painless white lesions?A. Black hairy tongueB. Fordyce's diseaseC. Lichen planusD. Nicotinic stomatitisE. White spongy nevus

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E. White spongy nevusThe correct answer is E. White sponge nevus (choice E) is a congenital condition that alters the texture of the oral, vaginal, and/or anal mucosa. It causes painless lesions that are typically "pearly" white in appearance. Hairy tongue (choice A) is a disorder that results in the elongation of filiform papillae of the tongue leading to the characteristic brown-black color of the dorsum of the tongue. Fordyce's disease (choice B) causes either buccal and/or labial mucosal lesions. This condition causes an aggregation of numerous small yellowish spots beneath the mucosal surface. Lichen planus (choice C) affects both the skin and oral mucus membranes. In addition to the characteristic violaceous lesions which are usually etched with fine grayish-white lines (Wickham's striae), one may see white scaly areas over a light pink base similar to psoriasis. Furthermore, lichen planus usually causes lesions to appear on the buccal mucosa, tongue, gingiva and/or lips. Nicotinic stomatitis (choice D) is typically found on the hard palate of pipe smokers and is characterized by several white elevations with a central red area.

Front 363

Which of the following is a demyelinating disease of the central nervous system?1. Multiple sclerosis2. Alzheimer's disease3. Parkinson's disease4. Creutzfeldt-Jakob disease

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1. Multiple sclerosisThe correct answer is choice 1. Let's briefly review the diseases or conditions listed. Choice 1, multiple sclerosis, or MS is a demyelinating disease of the central nervous system. It is characterized by a changing disease course of exacerbations and remissions with hyperreflexia. weakness and spasticity. In addition, dysfunction of the cerebellum may occur. The etiology is possibly autoimmune with influence by a viral infection. Alzheimer's disease, choice 2, is incorrect. Alzheimer's is a form of dementia with unknown etiology. Atrophy of the cerebral cortex occurs with loss of neurons and tangled areas known as neurofibrillary tangles. Demyelination is not involved. Parkinson's disease, choice 3, involves degeneration of neurons in the nucleus basalis, and dopamine depletion. It is often treated with L-dopa, a dopamine precursor. However, demyelination is not involved. Choice 4, Creutzfeldt - Jakob's disease, is a disease of the cortex and basal ganglia caused hy slow acting virus-like agents. Personality changes, incoordination, dementia and death eventually occur. However, demyelination is not involved. So the correct answer to question is choice 1.

Front 364

Which of the following is a DNA virus?A. Hepatitis AB. Hepatitis BC. Hepatitis CD. Hepatitis DE. None of the above

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B. Hepatitis BThe correct answer is choice B. Hepatitis B is the only hepatitis virus that is a double stranded DNA virus. It is a member of the Hepadnavirus family, and is associated with sexual and bloodborne transmission. It is known as long incubation "serum hepatitis". Hepatitis A is an RNA enterovirus. Thus it is a single strand virus. You should also know it as a short incubation hepatitis transmitted by the fecal/oral route. Hepatitis C has been identified as a single strand RNA virus. It used to be more commonly transmitted by transfusions, but a test for the virus now has reduced that type of spread. Hepatitis D is caused by the Delta particle, a single stranded RNA virus. Only persons infected with Hepatitis B can be infected with Hepatitis D. Hepatitis E is another RNA enterovirus, although less is known about it than Hepatitis A.

Front 365

Which of the following is a fungus that is known to produce small ulcerative lesion in the mouth, primarily on the tongue and gingiva?A. Bacteroides fragilisB. Candida albicansC. Clostridium perfringensD. Histoplasma capsulatumE. Streptococcus mutans

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D. Histoplasma capsulatumThe correct answer is D. Histoplasma capsulatum (choice D) is a fungus that is associated with the development of small ulcerative lesions in the mouth, particularly on the tongue, gingiva or palate. Furthermore, hoarseness and dyspahgia may occur, secondary to the lesions in the larynx. Fever and malaise are also commonly seen. Bacteroides fragilis (choice A) is an anaerobic organism commonly associated with the development of adult peridontitis and acute necrotizing ulcerative gingivitis. Acute necrotizing ulcerative gingivitis is associated with inflammation of the gingiva with necrosis, tissue loss, pain, bleeding and halitosis. Candida (choice B), a fungus, is the most common cause of "oral thrush", which is typically associated with the appearance of white patches in the mouth that can be easily wiped off to reveal a red, bleeding, sore surface. Clostridium perfringens (choice C) is the bacteria most commonly associated with the development of clostridial myonecrosis (gas-gangrene) and food poisoning. Streptococcus mutans (choice E) is a gram positive aerobic bacteria that is commonly associated with the development of dental caries, a destructive disorder of the hard tissues of the teeth.

Front 366

Which of the following is a Group A betahemolytic Streptococcus?A. S. mitisB. S. pyogenesC. S. sanguisD. S. salivariusE. S.mutans

Back 366

B. S. pyogenesThe correct answer is choice B. Srreptococcuis pyogenes is a pathogenic Strep of the Group A beta hemolytic group. It is involved in a wide range of diseases, including pharyngitis, scarlet fever, rheumatic fever and glomerulonephritis. All of the other Streptococci listed are Viridans Streptococci, which are non-hemolytic. They are normal oral flora, and are usually non-pathogenic. They can cause subacute endocarditis in susceptible individuals, however. This is the basis of antibiotic prophylaxis for dental procedures. In otherwise healthy individuals, the only other damage caused by these organisms is dental caries (especially S. mutans).

Front 367

Which of the following is a significant effect of pheochromocytoma?1. Myxedema2. Acromegaly3. Glycosuria4. Hypertension

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4. HypertensionThe correct choice is choice 4, hypertension. Pheochromocytoma is a tumor of chromaffin cells. Most of these tumors are located in the abdomen and 80% are found in the adrenal medulla. Another common site is a the aortic bifurcation. These neoplasms secrete catecholamines, especially norepinephrine, which causes paroxysmal hypertension. The hypertension is relieved when the tumor is resected. Myxedema, choice 1, is a term for the clinical syndrome resulting from hypothyroidism. This syndrome is characterized by generalized lethargy and slowing of mental and motor functions, coarse skin, hoarse voice, peripheral and periorbital edema, and in extreme cases, coma. Acromegaly, choice 2, results from hypersecretion of growth hormone. It is characterized by enlargement of the jaw, hands and feet, and coarsening of the facial features. Glycosuria, choice 3, literally means sugar in the urine. It results whenever glucose filtration exceeds glucose resorption. It commonly occurs in diabetes mellitus, but may also be found in renal tubular disease. So the correct choice to question is choice 4.

Front 368

Which of the following is an example of naturally-acquired passive immunity in humans?1. Tetanus immunization2. Injection of gamma globulin3. Transfusion of immune blood4. Placental transfer of antibody5. Antibody produced during recovery from measles

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4. Placental transfer of antibodyThe correct choice is choice 4, placental transfer of antibody. Passive immunity occurs when a recipient receives antigen-specific immunoglobulins from a donor. Placental transfer of antibody is an example of passive immunity which occurs naturally and is fundamental to life. Infants prior to six months of age are incapable of generating adequate antibody to fight infections. During this period of immune maturation, they are dependent on maternal antibodies which are acquired prenatally across the placenta and postnatally in breast milk. The only immunoglobulins which can cross the placenta are those of the IgG class, but this is adequate to maintain health. Tetanus immunization, choice 1, is an example of active immunity. The individual is injected with tetanus toxoid, a molecule which is antigenically similar to tetanus toxin, but lacks its biologic effects. An immune response is induced and the individual synthesizes immunoglobulins specific for tetanus toxoid and toxin. Injection of gammaglobulin, choice 2, is an example of m passive immunity, but it does not occur naturally. Gammaglobulin is administered by a healthcare practitioner to an individual who has recently been exposed to an infectious agent such as hepatitis B. The gammaglobulin neutralizes the virus before infection can occur. Transfusion of immune blood, choice 3, is similar to choice 2. It is passive immunity, but is not a natural process. Immune blood is rich in various antibodies and it is given to individuals who cannot synthesize immunoglobulins. Antibody produced during recovery from measles, choice 5, is a classic example of active immunity. The virus induces an immune response in the host. The process is a natural one, but no antibody donor is involved as in placental transfer of IgG. Once again, the correct choice to question is choice 4.

Front 369

Which of the following is an RNA virus?A. Herpes simplexB. Varicella zoster virusC. Hepatitis AD. CytomegalovirusE. Epstein-Barr virus

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C. Hepatitis AThe correct answer is choice C. This is not just a memory question but a grouping question. The herpes viruses are all DNA viruses and include Herpes simplex I and II (choice A), cytomegalovirus (CMV) (choice D), Epstein-Barr virus (EBV) (choice E), and varicella zoster virus (VZV) (choice B). Hepatitis A is an RNA virus, as is Hepatitis C and D. Only Hepatitis B is a DNA virus among the hepatitis viruses.

Front 370

Which of the following is characteristic of a prokaryotic cell?1. Mitochondrion2. Nuclear membrane3. Single chromosome4. Endoplasmic reticulum

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3. Single chromosomeThe correct choice is choice 3, single chromosome. Two fundamental cell types exist. Prokaryotic cells are very simple cells. The bacteria and the blue algae are essentially modified prokaryotic cells. These cells lack specialized organelles such as a nucleus with its nuclear membrane (choice 2), mitochondria (choice 1), endoplasmic reticulum (choice 4), Golgi bodies, peroxisomes and lysosomes. They lack a cytoskeleton and they are incapable of the cytoskeleton-dependent processes of endocytosis and exocytosis. These cells are quite small, measuring only one to ten micrometers in length and they rarely aggregate to form multicellular units. Many prokaryotes lack enzymes of the Krebs' cycle and are therefore dependent on glycolysis for their ATP production. DNA is found in the cytoplasm and it exists, as stated in choice 3, as a single chromosome. This chromosome is organized in a large circular strand rn which does not condense when the organisms divide by binary fission. Eukaryotic cells, by contrast, localize their DNA in the nucleus. There. the genetic material is organized into discreet bundles which undergo condensation when the cell divides by mitosis. Eukaryotic cells have a host of organelles lacking in the prokaryote. The eukaryote utilizes the Krebs' cycle and can thus generate more ATP per molecule of glucose metabolized. These cells can be quite large. Some measure 100 micrometers in length. They a possess a complex cytoskeleton and are capable of endo- and exocytosis, and most eukaryotic cells are organized in multicellular systems wherein each cell is specialized for a different function. All fungi, plants and animals are composed of eukaryotic cells. Once again, the correct choice to question is choice 3.

Front 371

Which of the following is characterized by a collapse of alveoli?1. Empyema2. Pneumonia3. Emphysema4. Atelectasis5. Bronchiectasis

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4. AtelectasisAtelectasis refers to collapse of alveoli and is often found in cases of asthma of the allergic type. Choice 1 is incorrect. In empyema, the pleura are filled with purulent exudate; no alveolar collapse occurs. Choice 2 is incorrect. In bacterial pneumonias, alveoli are filled with purulent exudate. In viral or mycoplasmal pneumonia, alveoli are often covered by hyaline membrane. Choice 3 is incorrect. In emphysema, alveolar septa are destroyed, sometimes leading to confluent distended air spaces. Choice 5 is incorrect. In bronchiectasis, bronchi and bronchioles dilate abnormally. So the correct answer to question is choice 4.

Front 372

Which of the following is characterized by a cumulative antimicrobial effect?1. Iodine2. Alcohol3. Cationic detergent4. Acid glutaraldehyde5. Chlorhexidine gluconate

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5. Chlorhexidine gluconateThe correct choice is answer #5, chlorhexidine gluconate. Chlorhexidine is an antiseptic which kills gram-positive bacteria and other organisms by disrupting their plasma membranes. When chlorhexidine is used repeatedly on the skin, the chemical accumulates to produce an enhanced antimicrobial effect. By contrast, the agents listed in choices 1 through 4 do not show this property. Iodine, choice 1, kills microorganisms by an unknown mechanism. It is effective against live bacteria and spores, and it is the most widely used antiseptic in hospitals. Alcohol, choice 2, works as an antiseptic by precipitating protein. It is not effective against spores, however. Cationic detergents, choice 3, include silver and mercury compounds. Silver ions are effective agents for precipitating proteins and interfering with bacterial metabolism. Mercury ions also precipitate proteins, but they have an added effect of self-hydro-enzyme inhibition. Acid glutaraldehyde, choice 4, also kills microorganisms by precipitating proteins. It is effective against spores only when applied for several hours. Once again, the correct choice to question is choice 5.

Front 373

Which of the following is CORRECT for obligate anaerobic microorganisms in the oral cavity?A. They do not exist in this area.B. Only gram-positive organisms are found.C. They are normal flora and opportunistic.D. They are seldom isolated in the laboratory.E. They can be completely controlled by using antibiotics.

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C. They are normal flora and opportunistic.The correct answer is choice C. Many gingival sulcus and periodontal pathogens are anaerobic. They are part of the normal flora and become pathogenic under certain host conditions, including lowered resistance and inadequate plaque and calculus control. They can be either gram positive or gram negative. For example, Actinobacillus is gram negative, while Eubacterium is gram positive. Some of these anaerobes can be isolated in the laboratory, although spirochetes are difficult or impossible. Bacteria can be controlled to some extent through antibiotic use (penicillin for odontogenic infections, streptomycin for some periodontal infections, etc.). However, complete control is clearly impossible. The mouth is full of microorganisms, and the mouth cannot be made sterile through antibiotic use. So the correct answer to question is choice C.

Front 374

Which of the following is diagnosed by karyotyping?1. Phenylketonuria2. Neurofibromatosis3. Tay-Sachs disease4. Turner's syndrome5. Sickle cell anemia

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4. Turner's syndromeThe correct answer is choice 4.Karyotyping involves the counting and typing of chromosomes; in particular, disorders in number of chromosomes such as Down's syndrome, or number and type of sex chromosomes such as Turner's or Klinefelter's syndrome, can be detected by karyotyping. Turner's syndrome refers to a condition of 45 total chromosomes with one X and no Y chromosomes, also known as XO. Choice 1, phenylketonuria, is a disorder of phenylalanine metabolism. This is detected by a bacterial inhibition assay. Choice 2. neurofibromatosis, is a tumor of Schwann cells. It is hereditary and is associated with pigmented cafe au lait skin lesions, neural tumors and pigmented tumors of the iris. Choice 3, Tay-Sachs, is a disorder of sphingolipids and is detected by enzyme assay. Choice 5, sickle cell anemia, is a hereditary protein formation disorder leading to defective hemoglobin and red blood cells. It is detected through microscopic exam of blood smears. So the only choice which is detected by karyotyping is choice 4, Turner's syndrome, and the correct answer to question is choice 4.

Front 375

Which of the following is elevated in the serum of patients with prostate cancer?1. Acid phosphatase2. Alpha-fetoprotein3. Alkaline phosphatase4. Carcinoembryonic antigen

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1. Acid phosphataseThe correct choice is choice 1, acid phosphatase. Various serum enzymes have been helpful in following patients with cancer. In general, these enzymes cannot be utilized to screen patients for the presence of cancer because elevations of serum levels of these enzymes can be due to a variety of causes. However, once a primary tumor has been discovered, measurement of these enzymes correlates with the progression of the disease. Consider the following example: A 67-year-old black male has a hard nodule measuring 1 cm on his prostate discovered on routine exam. His serum acid phosphatase at that time was twice normal. Following prostatectomy, the acid phosphatase level was normal. He was followed with acid phosphatase measurements every six months. Two years post-op, his acid phosphatase was six times normal. The patient also complained of back pain. A bone scan revealed diffuse bony metastases. This scenario is quite typical of patients with prostatic cancer. Alpha-fetoprotein, choice 2, is generally elevated in patients with hepatocellular carcinoma or yolk sac tumors. Alkaline phosphatase, choice 3, is the least specific of the enzymes given in this question. It is an enzyme found primarily in liver and bone and is often elevated in both benign and malignant diseases involving these tissues. Of note, patients with prostatic cancer may have elevated alkaline phosphatase levels, but this results from bone or liver metastases. It is not secreted by the tumor directly. Carcinoembryonic antigen, choice 4, is elevated primarily in patients with adenocarcinomas of the colon or lung and in various benign conditions. Once again, the correct choice to question is choice 1.

Front 376

Which of the following is MOST closely related to Mycobacterium tuberculosis?A. M. bovisB. M. kansasiiC. M. aviumD. M. intracellulare

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A. M. bovisThe correct answer is choice A. All of the Mycobacteria listed are related to M. tuberculosis; however. M. bovis is most closely related. It causes bovine tuberculosis and can infect people who drink unpasteurized milk. The other species listed are known as atypical mycobacteria. They are soil-based organisms, but they take on special significance in immunocomprnmised patients who have difficulty defending against these organisms. Atypical mycobacterial infections are common in AIDS patients and are AIDS-defining.

Front 377

Which of the following is most commonly associated with development of gastrointestinal cancer?1. Diverticulosis2. Villous adenoma3. Pedunculated adenoma4. Meckel's diverticulum5. Duodenal peptic ulcer

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2. Villous adenomaThe correct choice is choice 2, villus adenoma. A villus adenoma most commonly occurs in the rectum or sigmoid colon. Villus adenomas are usually not pedunculated, but have a broad short base. Histologically, these lesions show cellular atypia with mitoses. Carcinoma in situ or invasive carcinoma is found in roughly 40% of all lesions. Therefore, when the diagnosis of villus adenoma is made, colonic resection must be performed. Diverticulosis, choice 1, is a common disorder of the colon characterized by multiple herniations of the colonic mucosa. These herniations arise at points of muscular weakness under conditions of increased intraluminal pressure. Diverticula often bleed or become infected, but they do not undergo malignant degeneration. Pedunculated adenoma, choice 3, is also called tubular adenoma. This lesion has a slender stalk and a broad head. Histologically, the cells show atypia, but mitotic figures are rare. When tubular adenomas are small, the risk that they will contain a malignant focus is less than 1%. As the lesions enlarge, however, the risk of cancer increases. Meckel's diverticulum, choice 4, is a remnant of the omphalomesenteric duct. It can usually be found in proximity to the ileocecal valve. These diverticula may bleed or perforate, but they are not associated with cancer. Duodenal peptic ulcer, choice 5, arises in individuals who have increased gastric acid secretion. Duodenal ulcers may bleed, perforate or obstruct the gastrointestinal tract, but they never undergo malignant change. Gastric ulcers, by contrast, are malignant in about 1% of cases. Once again, the correct choice to question is choice 2.

Front 378

Which of the following is MOST likely to cause a sudden arrest of heart function?A. Mitral stenosisB. Angina pectorisC. Constrictive pericarditisD. Cardiac tamponadeE. Subacute bacterial endocarditis

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D. Cardiac tamponadeThe correct answer is choice D. Cardiac tamponade refers to a condition in which fluid fills the pericardial space, produces pressure on the ventricles and prevents filling of the ventricles during diastole. This is an acute life threatening condition. Mitral stenosis involves limited motion of the mitral valve and causes chronic heart dysfunction. Angina pectoris is heart pain caused by poor blood flow in the coronary arteries. It will not usually lead to sudden cardiac arrest. Constrictive pericarditis involves the growth of fibrous tissue in the pericardium, causing decreased ventricular filling, but the condition is not acute. Subacute bacterial endocarditis involves infection of heart valves by bacteria. usually streptococci. Results may include valve damage, myocardial abscess, and septic emboli. However, it does not involve sudden cardiac arrest. So the correct answer to question is choice D.

Front 379

Which of the following is NOT a common soil fungus?A. CandidaB. HistoplasmaC. CoccidioidesD. Blastomyces

Back 379

A. CandidaThe correct answer is choice A. As stated before, free-living soil fungi may be taken into the body, especially the lungs, and cause systemic disease. Histoplasma (choice B), Coccidioides (choice C), and Blastomyces (choice D) all fall into this category of fungal organism. Candida, on the other hand, is a member of the normal flora of mouth and skin and becomes an opportunistic pathogen. Oral candidiasis is common, both in the immunocompromised and in patients receiving long-term antibiotics. Oral candidiasis is common in HIV+ individuals, and pharyngeal or esophageal candidiasis is AIDS-defining.

Front 380

Which of the following is NOT linked to fulminant hepatitis?A. Hepatitis AB. Hepatitis BC. Hepatitis CD. IsoniazidE. Carbon tetrachloride

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A. Hepatitis AThe correct answer is choice A. Most forms of hepatitis can lead to fulminant hepatitis (massive liver necrosis). In fulminant hepatitis, there is progressive loss of liver function and progressive shrinking of liver size due to hepatocyte death. Mortality is high. Both hepatitis B and C (choices B and C) can cause this state. Hepatitis A is always self-limiting with complete recovery and no chronic carrier stage. Less well known is the ability of chemicals to cause fulminant hepatitis. INH (isoniazid) (choice D), used in treating tuberculosis, can have this side effect. A group of related organic solvents (carbon tetrachloride [choice E], chloroform) are also dangerous in this way, and occupational exposure must be strictly monitored.

Front 381

Which of the following is NOT true concerning benign prostatic hypertrophy (BPH)?A. It commonly leads to carcinoma of the prostateB. Incidence increases with ageC. Tissue may be glandular or fibrousD. It often causes urinary obstructionE. It is not considered a neoplasm

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A. It commonly leads to carcinoma of the prostateThe correct answer is choice A. BPH (benign prostatic hypertrophy) is a non-neoplastic condition (choice E) in which the prostate gland enlarges and compresses surrounding tissue. This hypertrophy is composed of normal prostate cells, either glandular or fibromuscular (choice C). Signs and symptoms often include difficulty in urination (choice D), and incidence increases with age (choice B), beginning at around age 45. Ninety-five percent of men greater than 70 years of age have some form of this condition. There may be a hormonal etiology, although it is not yet clear. It is not believed to predispose to cancer of the prostate.

Front 382

Which of the following is NOT true concerning Paget disease?A. It is also known as osteitis deformansB. It may be discovered due to change in hat sizeC. Affected areas may be warm to the touchD. It is associated with an extremely low alkaline phosphataseE. It often results in deafness

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D. It is associated with an extremely low alkaline phosphataseThe correct answer is choice D. Paget disease is also known as osteitis deformans (choice A) or Paget disease of bone. It is usually polyostotic (affecting many bones), but effects on the skull may be most noticeable including increasing skull size (choice B) and loss of hearing (choice E) due to impingement of CN VIII. There is increased vascularity of bone and accompanying warmth of the skin over these areas (choice C). Bone processes may be osteolytic or osteoblastic, as bone is dissolved, replaced by fibrous tissue, remineralized, etc. Radiographic appearance may vary due to these changes. The consistent lab finding is extremely elevated alkaline phosphatase.

Front 383

Which of the following is the most common initial sign or symptom in patients with malignant lymphoma?1. Pallor2. Weight loss3. Lymphadenopathy4. Chronic infection5. Unexplained fever

Back 383

3. LymphadenopathyThe correct answer is choice 3.Lymphomas are lymphatic neoplasms characterized by lymphadenopathy and hepatosplenomegaly. Lymphomas are detected first in the lymph nodes, often the cervical chain. The other choices 2 and 5, weight loss and unexpected fever, are possible symptoms associated with lymphomas, but are not usually noticed first as they follow the lymphadenopathy. Choices 1 and 4, pallor and chronic infection, are not common symptoms of patients with lymphomas. So the correct answer to question is choice 3.

Front 384

Which of the following is the most common type of lung cancer?1. Adenocarcinoma2. Bronchiolar carcinoma3. Alveolar cell carcinoma4. Squamous cell carcinoma5. Anaplastic (oat cell) carcinoma

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4. Squamous cell carcinomaThe correct choice is choice 4, squamous cell carcinoma. Lung cancer is the most common cancer is men and may have surpassed breast cancer as the most common cancer in women. It is a devastating disease with a 5-year mortality rate of 90%. Roughly one-half of all lung cancers are squamous cell carcinomas. The next most common cancer of the lung is adenocarcinoma, choice 1, followed by oat cell carcinoma, choice 5. Large cell carcinoma, which is not listed in this question, is the fourth most cancer. Bronchiolar and alveolar cell carcinomas, choices 2 and 3 respectively, are subclassifications of adenocarcinomas. Alveolar cell carcinoma is rare. It represents approximate 3% of all malignant lung tumors. Once again, the correct choice to question is choice 4.

Front 385

Which of the following is the single MOST numerous group of microorganisms in the oral cavity?A. EnterococciB. StaphylococciC. Anaerobic streptococciD. Facultative streptococciE. Beta-hemolytic streptococci

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D. Facultative streptococciThe correct answer is choice D. This is an especially common NDB point. By far, most bacteria in the mouth are facultative streptococci. These organisms will survive in either aerobic or anaerobic conditions. Chief among these organisms are the non-betahemolytic Streptococci, such as S. mutans, S.salivarius and S. mitor. So the correct answer to question is choice D.

Front 386

Which of the following is true concerning carcinoma of the cervix?A. It is usually an adenocarcinomaB. Carcinoma in situ is rarely curableC. It is associated with specific virusesD. It is most common in the sixth to seventh decadesE. It is the most common malignant tumor in women

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C. It is associated with specific virusesThe correct answer is choice C. Cervical cancer is the sixth most common cause of cancer death in women (choice E). It is most common in the fourth to fifth decades (choice D), and it is believed that certain factors related to the disease can be passed from male to female, in particular, infection with either HSV II or HPV (human papilloma virus). Cervical cancer is typically a squamous cell carcinoma, not an adenocarcinoma (choice A). When confined to the outer epithelial tissue, without invasion of the connective tissue (carcinoma in situ), it is highly curable (choice B). Late disease has a much lower cure rate. Detection is, on average, much earlier in the last decade due to widespread use of the Papanicolaou test (Pap smear) as a yearly screening tool.

Front 387

Which of the following is typically elevated in the serum of patients with prostate cancer?1. Acid phosphatase2. Alpha-fetoprotein3. Alkaline phosphatase4. Carcinoembryonic antigen

Back 387

1. Acid phosphataseThe correct answer is choice 1. Prostatic acid phosphatase is known as a chemical tumor marker. When elevated, it indicates a prostate tumor which has extended outside the capsule of the prostate. Choice 2 is incorrect. Alphafetoprotein is another chemical tumor marker. Its presence indicates the presence of a hepatoma, an embryonal cell tumor of the testis, or a malignant teratoma. Choice 4 is incorrect. Carcinoembryonic antigen is another tumor marker which indicates the presence of any tumor derived from gut epithelium. It may also be elevated in smokers without tumors. Choice 3 is incorrect. Elevated alkaline phosphatase can be found in patients with Paget's disease of bone. So the correct answer to question is choice 1.

Front 388

Which of the following laboratory results is diagnostic of acute pancreatitis?1. Decreased albumin2. Elevated serum lipase3. Decreased serum amylase4. Elevated alkaline phosphatase

Back 388

2. Elevated serum lipaseThe correct answer is choice 2. Acute pancreatitis involves diffuse necrosis of the pancreas caused by release of activated pancreatic enzymes. Laboratory results reveal elevated amylase and lipase enzymes in the blood, and sometimes a hypocalcemia. Labs for chronic pancreatitis also reveal elevated amylase and alkaline phosphatase, but not lipase. So elevated lipase is more diagnostic of acute pancreatitis. So choice 2 is correct. Choice 3 is incorrect also because it says decreased serum amylase. Choice 4, elevated alkaline phosphatase, is characteristic of chronic pancreatitis, not acute, as well as other conditions, including Paget's disease of bone. So the correct answer to question is choice 2.

Front 389

Which of the following medications is effective in treating oral candidiasis?A. GriseofulvinB. Protease inhibitorC. TetracyclineD. MetronidazoleE. Nystatin

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E. NystatinThe correct answer is choice E. Oral candidiasis can be treated topically or systemically. The most common topical treatment is nystatin (rinse or troches), amphotericin B or clotrimazole. Systemic treatments include fluconazole and ketoconazole. Typically, early cases are treated with topical medications first. Griseofulvin is a systemic antifungal used for treating tinia, ringworm and athlete's foot. Tetracycline is an anti-bacterial used often in treating gingival infections. It should not be given to young children or pregnant women. It is bacteriostatic. Metronidazole (flagyl) is an agent effective against both anaerobic bacteria and many protozoans.

Front 390

Which of the following microorganisms is most likely to be cultured from chronic, bilateral ulcerations at the corners of the mouth?1. Candida2. Brucella3. Treponema4. Aspergillus5. Histoplasma6. Trichophyton

Back 390

1. CandidaThe correct answer is choice 1. Candida albicans is a fungal organism, part of the normal oral flora. It can cause problems under certain conditions including chronic ulcerations at the comers of the mouth. In edentulous patients, the loss of vertical dimension may cause drooping at the comers of the mouth and Candida infection may cause ulcerations at these points. Candida is also found infecting the tongue and buccal mucosa in immunocompromised patients such as AIDS patients. Choice 2 is incorrect. Brucella is a gram negative bacillus which can cause infections in man but not specifically at the corners of the mouth. Choice 3 is incorrect. Treponema are spirochetes, the most familiar of which is Treponema pallidum which causes syphilis. Choice 4 is incorrect. Aspergillus is a fungus which may invade the hand or foot of a farmer or rural worker usually from the soil. Choice 5 is incorrect. Histoplasma is a fungus which causes histoplasmosis, a fungal infection of in the lungs. It can be spread by bird excrement. Choice 6 is incorrect. Trichophyton is a fungus often involved in fingemail and toenail infections known as tinea unguium. So the correct answer to question is choice 1.

Front 391

Which of the following most accurately describes the antibacterial mechanism of penicillin?1. Inhibits DNA synthesis2. Inhibits the terminal step in peptidoglycan synthesis3. Inhibits protein synthesis in growing bacterial cells4. Disrupts the integrity of the cell membrane

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2. Inhibits the terminal step in peptidoglycan synthesisThe correct choice is choice 2, inhibits the terminal step in peptidoglycan synthesis. Both gram-positive and gram-negative bacteria have cell walls composed of peptidoglycans which encase their plasma membrane. Peptidoglycans are composed of polymers 4 of N-acetylglucosamine, N-acetylneuraminic acid and amino acids. These polymers are cross-linked to form a stable barrier in the terminal step of peptidoglycan synthesis. Penicillin interferes with this cross-linking step and thereby prevents the formation of a durable cell coat. Affected organisms become highly susceptible to rupture and fragmentation as a result. Other antibiotics which interfere with cell well synthesis include bacitracin, the cephalosporins and vancomycin. Some antibiotics exert their effect by disrupting cell membranes of pathogenic organisms as mentioned in choice 4. Antibiotics in this class include the antifungal agents, amphotericin-B and nystatin. These agents form channels in the fungal wall and disrupt ion gradients required for normal metabolism. Other antibiotics act as mentioned in choice 3, through protein synthesis inhibition. Antibiotics in this class include the aminoglycosides, chloramphenicol. erythromycin and tetracycline. Finally, drugs such as rifampin, sulfonamides and trimethoprim are effective antimicrobial agents through the inhibition of bacterial DNA synthesis which is mentioned in choice 1. Once again, the correct choice for question is choice 2.

Front 392

Which of the following neoplasms appears the MOST often in children?B. ChondrosarcomaC. AdenocarcinomaD. Multiple myelomaE. Basal cell carcinoma

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A. NeuroblastomaThe correct answer is choice A. Neuroblastoma is the most common extracranial solid tumor in children. It is often found in the adrenal medulla, causes elevated catecholamines and metastasizes readily. Chondrosarcoma is a malignant tumor of chondroblasts, found mostly in adults 30-60, male more often than female. The most common adenocarcinoma is found in glandular elements of the respiratory tract, especially in male adult smokers between 40-70 years old. Multiple myeloma is a neoplasm of plasma cells resulting in excessive abnormal immunoglobulins, including Bence-Jones proteins. It is most common in adults 50-60 years old. Basal cell carcinomas are malignant skin neoplasms most common in middle aged and older adults. So the correct answer to question is choice A.

Front 393

Which of the following organisms causes pneumonia exclusively in immunocompromised individuals?A. DiplococcusB. Pneumocystis cariniiC. Mycoplasma pneumoniaeD. Legionella pneumophilaE. Influenza virus

Back 393

B. Pneumocystis cariniiThe correct answer is choice B. Pneumocystis carinii pneumonia (PCP)is found exclusively in immunocompromised patients. It is common in AIDS patients, but other immunocompromised individuals may have the disease as well. It is one of many forms of pneumonia, including bacterial, chemical, and viral. Ali of the other organisms listed in the question can cause pneumonia; however, only PCP is exclusively found in individuals with damaged immune systems. Note that Legionnaires disease, caused by L. pneumophila, is more common in the elderly and immunocompromised, but it is not exclusive to them. Note also that PCP is currently classified as a fungus and had been formerly classified as a protozoan. PCP pneumonia is usually treated with sulfamethoxazole-trimethoprim.

Front 394

Which of the following organisms is the most common cause of scalded-skin syndrome?A. Escherichia coliB. Haemophilus influenzaeC. Pseudomonas aeruginosaD. Staphylococcus aureusE. Streptococcus pneumoniae

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D. Staphylococcus aureusThe correct answer is D. Scalded-skin syndrome (SSS) is a condition characterized by a redness and tenderness of the central face, neck, trunk, and intertriginous zones. This initial presentation is followed by the appearance of flaccid bullae and a slough or exfoliation of the superficial epidermis. The majority of the cases of SSS are caused by Staphylococcus aureus. Escherichia coli (choice A) is a gram negative organism commonly seen in urinary tract infections. Haemophilus influenzae (choice B) is gram-negative organism commonly seen in individuals with pneumonia, meningitis, respiratory infections, sinusitis and otitis infections. Pseudomonas aeruginosa (choice C) is a gram-negative organism associated with serious respiratory infections. These bacteria are most often seen in individuals receiving respiratory support. Streptococcus pneumoniae (choice E), as the name suggests, is the causative organism of pneumococcal pneumonia.

Front 395

Which of the following organisms, described as being an encapsulated yeast, is the most common cause of fungal meningitis?A. AspergillusB. CandidaC. CoccidioidesD. CryptococcusE. Pneumocystis

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D. CryptococcusThe correct answer is D. Cryptococcosus is the most common cause of fungal meningitis. This type of meningitis is caused by the organism Cryptococcus neoformans, which is classified as an encapsulated budding yeast. This infection is acquired by inhalation and is most commonly seen in HIV-infected individuals. The organism Aspergillus fumigates (choice A) is associated with the development of Aspergillosis, which is an allergic bronchopulmonary disease. Candida albicans (choice B) primarily affects the gastrointestinal mucosa and is also known to cause candidal endocarditis. Coccidioides immitis (choice C) is a mold that grows in the soil of areas with arid climates. This organism typically causes respiratory tract infections, which can lead to arthralgia and periarticular swelling when this infection spreads to the bones. Pneumocystis carinii (choice E) is a fungus which causes bilateral diffuse interstitial pneumonia. This type of pneumonia is most often seen in HIV-infected individuals.

Front 396

Which of the following organs is the most uncommon site for infarcts?1. Brain2. Heart3. Liver4. Kidney5. Adrenals

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3. LiverThe correct answer is choice 3. Infarctions are regions of tissue necrosis resulting from acute decrease in blood supply. They occur primarily when arterial flow is disrupted. In this question, we will find the most uncommon site for infarcts by selecting the liver as the organ best supplied with blood. The blood supply to the liver is so extensive and overlapping that decreased flow in one artery or arteriole does not necessarily compromise the supply to the area as an overlapping supply exists from a nearby artery or arteriole. In addition, the liver has what is known as a dual blood supply, with each area receiving blood not only from the hepatic artery, but also from the hepatic portal vein. Choice 1, the brain, is a common site for infarcts. These infarcts are commonly known as strokes. Choice 2, the heart, is incorrect. Myocardial infarction, commonly known as a heart attack, is also a common condition. Choices 4 and 5, while not common places for infarcts, do have infarcts occasionally and do not have a dual blood supply. So the correct answer to question is choice 3.

Front 397

Which of the following particles does NOT contain HbsAg?A. Dane particleB. SpheresC. Tubules (filaments)D. Delta particle

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D. Delta particleThe correct answer is choice D. The Hepatitis B surface antigen( HbsAg) is an antigenic component found on a variety of particles of Hepatitis B. The actual hepatitis B virus (HBV) is a DNA virus and the particle is known as the Dane particle (choice A). It contains both DNA and a protein coat. Excess production of the protein coat results in the presence of spheres (choice B) and tubules (filaments) (choice C) of protein coat, which also contain the surface antigen. The Dane particle also contains the two other Hepatitis B antigens, known as the core antigen and the e-antigen. Delta antigen is a component of Hepatitis D or delta hepatitis. It can be transmitted only concurrently with hepatitis B but is a distinct disease entity with an RNA genome.

Front 398

Which of the following pneumoconioses is most often associated with bronchogenic carcinoma and mesothelioma in man?1. Silicosis2. Asbestosis3. Anthracosis4. Berylliosis

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2. AsbestosisThe correct choice is choice 2. asbestosis. Asbestos exposure has been linked to the development of mesothelioma and bronchogenic carcinoma. Mesothelioma is often a rapidly fatal tumor arising from the pleura or peritoneum. It is a very rare disease among the general population, but as many as 10% of heavily exposed individuals will develop mesothelioma. This cancer frequently shows a very long latency period. Often it does not occur for up to 50 years following asbestos exposure. The incidence of bronchogenic carcinoma is slightly increased among those exposed to asbestos. However, among those exposed who also smoke heavily, the incidence of bronchogenic carcinoma is increased up to ninety-fold as compared to controls. Silicosis, choice 1, is associated with both acute and chronic lung disease. In the acute form, an exudative pneumonitis occurs and death ensues within one year. In the chronic form, the patient's pulmonary function gradually deteriorates over many years. During these years, the lung is gradually replaced by fibrous tissue. Pulmonary tuberculosis complicates chronic silicosis as does rheumatoid arthritis. Anthracosis, choice 3, is a common lung finding among smokers and city dwellers. It refers to the accumulation of carbon in macrophages in the lung. Anthracosis by itself is of no clinical significance, but may be present in severe diseases including coal worker's pneumoconiosis. Berylliosis, choice 4, is a granulomatous disease of the lung resulting from heavy beryllium exposure. Exposure to beryllium has been associated with the development of bronchogenic carcinoma, but it has not been shown to play an etiologic role in the development of mesothelioma. Once again, the correct choice to question is choice 2.

Front 399

Which of the following represent(s) the MOST common source of pulmonary embolism?A. Esophageal varicesB. EndarteritisC. LymphangitisD. Buerger's diseaseE. Thrombophlebitis

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E. ThrombophlebitisThe correct answer is choice E. Pulmonary emboli are formed in the systemic venous system, travel through the right atrium, right ventricle, pulmonary artery, and then lodge in the lung. They are clots (thrombi) formed within veins, especially deep leg veins. Esophageal varices usually cause severe bleeding and are discussed in other questions. Endarteritis is inflammation of the lining of arteries, and lymphangitis is inflammation of the lining of lymph vessels. Neither causes pulmonary emboli. Buergers disease involves immune complexes causing damage to arteries and other vessels. It often causes thrombosis in legs. So the correct answer to question is choice E.

Front 400

Which of the following represents the chief complication of mumps in the adult male?A. OrchitisB. ProstatitisC. GlomerulonephritisD. Chronic nonspecific sialadenitis

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A. OrchitisThe correct answer is choice A. Orchitis is the swelling of the testes commonly found in male mumps patients. It often develops about 1 week after the parotid gland swelling. It is more common in older male patients (over l0), and less common in those less than 10. Prostatitis and glomerulonephritis are not generally associated with mumps. Sialadenitis (inflammation of the salivary gland) is associated with mumps, especially that of the parotid gland. However, it would be acute, not chronic, and is caused by the mumps virus, a paramyxovirus, and therefore is not nonspecific. So the correct answer to question is choice A.

Front 401

Which of the following represents the MOST frequent cause of a clinically palpable breast mass in an adult woman?A. SarcomaB. FibroadenomaC. AdenocarcinomaD. Fibrocystic diseaseE. lntraductal papilloma

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D. Fibrocystic diseaseThe correct answer is choice D. Fibrocystic disease is the most common breast disorder(more common than all tumors). It includes both fibrosis of areas of the breast and formation of serous fluid-filled cysts. Fibroadenoma is the most common tumor, and is benign, and usually single. Most malignant tumors of the breast are varieties of carcinomas, and not sarcomas. Intraductal papilloma is generally a solitary lesion within a duct or cyst. When single, it is usually benign. So the correct answer to question is choice D.

Front 402

Which of the following represents the MOST potent carcinogen?A. EstrogenB. BenzpyreneC. Folic acidD. Cholic acid

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B. BenzpyreneThe correct answer is choice B. Of the compounds listed, benzpyrene is by far the most potent carcinogen. Common proven chemical carcinogens include benzpyrene, benzene, aniline dyes, and asbestos. So the correct answer to question is choice B.

Front 403

Which of the following represents the MOST reliable postmortem indicator of left ventricular cardiac failure?A. AscitesB. Venous congestionC. Enlargement of the spleenD. Peripheral edema of the anklesE. Chronic passive congestion of the lungs

Back 403

E. Chronic passive congestion of the lungsThe correct answer is choice E. In left ventricular failure, the lungs become congested with tissue fluid. If you review the path of blood in the circulatory system, you will note that blood in the left ventricle comes from the left atrium. This blood in the atrium has just arrived in the pulmonary vein from the lungs. Ineffective pumping by the left ventricle therefore causes higher than normal pressure in the pulmonary vein and lungs, and congestion results. Other signs of left sided failure include hypoperfusion of the kidney and brain. Edema of the ankles, general systemic venous congestion, and ascites are generally signs of right sided failure, with an analogous backup of fluid into the systemic venous system, rather than the pulmonary. Ascites refers to edematous swelling of the abdomen. So the correct answer to question is choice E.

Front 404

Which of the following serum values is likely to be elevated in a patient with hyperparathyroidism?1. Calcium2. Chloride3. Potassium4. Phosphorus5. Acid phosphatase

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1. CalciumThe correct answer is choice 1.In hyperparathyroidism, especially the primary type, serum calcium is elevated. Choice 2, chloride, and choice 3, potassium, are unaffected. Choice 4, phosphorus, will be elevated in cases of hypoparathyroidism. Choice 5, acid phosphatase, is elevated in cases of prostatic carcinoma as discussed earlier. Alkaline phosphatase levels are elevated in Paget's disease of bone, although this is not a choice here. Anyway, the correct answer to question is choice 1.

Front 405

Which of the following species of streptococci is usually NOT found in human dental plaque?1. S. mutans2. S. sanguis3. S. pyogenes4. S. salivarius5. S. mitior S. (mitis)

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3. S. pyogenesThe correct choice is choice 3, S. pyogenes. Dental plaque is complex mixture of bacteria and dextran which adheres to teeth and causes dental caries. Many microorganisms may be cultured from dental plaque, the most common of which are Streptococcal species. Step. mutans, mitor and sanguis are present in high amounts, but some Strep. salivarius is deposited from saliva. In addition to these organisms, the following organisms are among those found in dental plaque: Staph. epidermitis, Neisseria, Actinomycin and Haemophilus. Strep. pyogenes is a pathogen of the pharynx where it causes Streptococcal pharyngitis. If not adequately treated, Streptococcal pharyngitis may induce glomerular nephritis or rheumatic fever. Strep. pyogenes also causes cellulitis, lymphangitis, impetigo, and post-partum infections of the uterus. Once again, the correct choice for question is choice 3.

Front 406

Which of the following viral-associated enzymes is unique to RNA tumor viruses?1. Neuramidase2. Capping enzyme3. Reverse transcriptase4. DNA-dependent RNA polymerase

Back 406

3. Reverse transcriptaseThe correct choice is answer #3. The fundamental axiom of modern biology states that protein synthesis proceeds from DNA to RNA to protein. The RNA viruses consist of merely a protein coat surrounding an RNA nucleic acid core. These viruses are able to replicate and synthesize protein only by first generating DNA. This is accomplished with the use of reverse transcriptase which synthesizes DNA from an RNA template. Once DNA is formed, the DNA acts as a template for RNA synthesis. Some of this RNA will form the core of the new virus particles. However, much of this RNA is messenger RNA utilized for the production of viral proteins including reverse transcriptase. Neuraminidase is an enzyme present in the outer membrane of para-myxoviruses and orthomyxoviruses which are RNA viruses, but is also produced by the bacteria Vibrio cholerae. Consequently, choice 1 is incorrect. This enzyme cleaves N-acetylneuraminic acid, also called NANA, from glycoproteins on the surface of red blood cells. NANA is essential for hemoagglutination. Thus, neuraminidase inhibits this process. Capping enzymes, choice 2, are present in all cells. They are not present in viruses. These proteins attach to the ends of cytoskeletal proteins and determine the rate at which these ends elongate or depolymerize. They play a vital role in determining cell shape. DNA-dependent RNA-polymerase is present in all animal cells. Choice 4 is therefore incorrect. This enzyme or group of enzymes is responsible for transcription, the process whereby RNA is formed from a DNA template. So the correct choice to question is answer 3.

Front 407

Which of the following viruses causes two distinct diseases in different age groups?1. Influenza2. Measles3. Smallpox4. Varicella5. Newcastle disease

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4. VaricellaThe correct choice is choice 4, Varicella. The Varicella zoster virus, a herpes virus, causes chicken pox in young children. Following infection, the virus enters a dormant phase in the dorsal ganglia. Reactivation of the virus occurs under conditions of fir decreased immunocompetence. Elderly individuals have a less vigorous immune system and reactivation commonly occurs in this population. Reactivation rarely causes disseminated disease. It commonly presents as vesicular lesions confined within a single dermatome in a condition known as shingles. The lesions are quite painful and they are fully infectious. Influenza, choice 1, destroys the respiratory mucosa of infected individuals. Elderly individuals may succumb more readily to complications of this disease, but the disease that they acquire is identical to that of their younger counterparts. Measles, choice 2, can manifest itself in a variety of ways. It most cc>mmonly causes a diffuse maculopapolar rash with severe constitutional symptoms. Less often, it causes pneumonia and encephalitis. Rarely, it causes subacute sclerosirlg panencephalitis (SSPE) which is a degenerative neurologic disease characterized by myoclonic jerks and motor deterioration. Pneumonia, encephalitis and SSPE are considered complications of measles infection. They can affect any individual infected with the measles virus and are not age-specific. Smallpox, choice 4, causes a diffuse vesicular skin rash similar to chicken pox. This virus has been eradicated worldwide due to successful vaccination programs. It no longer causes disease. Newcastle disease, choice 5, is a respiratory tract disease of chickens. The Newcastle disease virus, however, can cause disease in humans exposed. This disease is common among poultry workers and among researchers who work with the Newcastle virus. When humans are infected, they usually do not manifest respiratory symptoms as do chickens. Rather, they acquire a mild conjunctivitis. Once again, the correct choice to question is choice 4.

Front 408

Which of the following viruses is strongly associated with Burkitt's lymphoma and nasopharyngeal carcinoma?1. Adenovirus2. Cytomegalovirus3. Epstein-Barr virus4. Herpes simplex virus type I5. Herpes simplex virus type II

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3. Epstein-Barr virusThe correct answer is choice 3. Epstein Barr virus is the causative agent of infectious mononucleosis. It is in the herpes family that includes Herpes-simplex 1, choice 4, which causes herpes labialis and herpetic gingivostomatitis. Also in the family is herpes-simplex type 2, causative agent of genital herpes and neonatal herpes. Also in the same family is choice 2, CMV , or cytomegalovirus, causative agent of cytomegalic inclusion disease, a generalized infection of infants. Adenoviruses , choice 1, are not in the herpes family and cause a variety of respiratory, eye and gastrointestinal infections. Our answer, Epstein Barr virus, besides causing infection, is believed to be associated with the B-cell lymphomas, Burkitt's lymphoma and nasopharyngeal carcinoma, all neoplasms. The virus is not implicated in actually causing the neoplasm but is associated in some way with its development. So the correct answer to question is choice 3.

Front 409

Which organism is LEAST likely to be involved in lesions of chronic adult periodontitis?A. SpirochetesB. Bacteroides melaninogenicusC. CapnocytophagaD. Streptococcus mitisE. Fusobacteria

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D. Streptococcus mitisThe correct answer is choice D. Periodontal disease pathogens are usually anaerobic or capnophilic. The term capnophilic means "carbon dioxide-loving". In the anaerobic environment deep in the sulcus, the following genera are often said to contribute to the tissue destruction of periodontal disease: Bacteroides, Porphyromonas gingivalis, Borelia. Spirochetes, Capnocytophaga, Fusobacteria and Eichenella. Streptococci (mutans, mitis, sanguis, salivarius) are all gram positive facultative anaerobes that do not require anaerobic conditions to survive. They are Viridans streptococci, generally nonpathogenic, and not linked to periodontal disease, although S. mutans is clearly linked to caries.

Front 410

Which pair of bacterial genera produce spores?A. Clostridium and StaphylococciB. Bacillus and StreptococciC. Staphylococci and StreptococciD. Clostridium and BacillusE. Bacillus and Staphylococci

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D. Clostridium and BacillusThe correct answer is choice D. The two genera of spore forming bacteria are Clostridium and Bacillus. Clostridium is most known for causing gas gangrene, (C. perfringens), botulism, (C. botuiinum) and tetanus (C. tetani). Bacillus is known for anthrax (Bacillus anthracis) and food poisoning (B. cereus). Bacillus stearothermophilus is used for the autoclave spore test (biological monitor), due to the extreme conditions needed to kill its spores.

Front 411

A deficiency of choline in the diet may cause abnormalities in metabolism of1. lipids.2. proteins.3. minerals.4. carbohydrates.5. nucleoproteins.

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LIPIDSThe correct answer is choice 1. Choline is a structural component of phosphatidylcholine or lecithin, a phosphoglyceride. Phosphoglycerides are major components of cell membranes. The raw material for the synthesis of phosphatidylcholine is dietary choline. In the absence of choline, phosphatidylcholine cannot be produced and a major phospholipid component of wall membranes will be unavailable. So the correct answer to question is choice 1. Choline is not directly involved in the metabolism of the other choices: proteins, minerals, carbohydrates or nucleoproteins.

Front 412

Which of the following characterize the links between monomeric units of nucleic acids?1. Ionic bonds2. Glycosidic bonds3. Phosphodiester bonds4. Phosphotriester bonds

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PHOSPHODIESTER BONDSThe correct answer is choice 3. Monomeric units of DNA consist of a phosphate group, deoxyribose, sugar, and nitrogen base of adenine, guanine, cytosine or thymine. These monomeric units are linked together to form the DNA strand by phosphodiester bonds. In these bonds, the 3-prime carbon of one deoxyribose links with one oxygen of the phosphate group, while a 5-prime carbon of another deoxyribose links with another oxygen of the phosphate group. This is known as a phosphodiester bond, indicating two bonds to a phosphate group. So the correct answer to question is choice 3.

Front 413

In anaerobic glycolysis, glucose is broken down into pyruvic acid, which is then primarily converted toA. Acetyl-CoAB. Citric acidC. GlycogenD. Lactic AcidE. Creatinine phosphate

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LACTIC ACIDThe correct answer is D. The anaerobic process of glycolysis enables the cell to create ATP when the mitochondria are unable to meet the "current" energy demands in the absence of oxygen. When the local area is oxygen deficient, glucose is still converted into pyruvic acid, which is subsequently converted to lactic acid. Lactic acid is an organic acid that in the body dissociates into a lactate ion and a hydrogen ion. This process is a temporary solution to maintain the energy demands of the body; however, when the muscle is continually subjected to this anaerobic state, it will cease to contract secondary to the low pH. In the presence of oxygen (aerobic glycolysis) glucose is broken down into pyruvic acid, which is then primarily converted to Acetyl-CoA (choice A), which then enters the TCA cycle. The formation of citric acid (choice B) is the first step in the TCA cycle. Glycogen (choice C) is the storage form of glucose. In skeletal muscle, some of the ATP generated is transferred and stored in another high-energy compound, creatinine phosphate (choice E). The energy stored in this compound is used to "recharge" ADP to ATP during muscle contractions.

Front 414

In males, growth and development of secondary sex organs are under direct control of1. FSH and LH.2. aldosterone.3. progesterone.4. testosterone

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TESTOSTERONEThe correct choice is #4, testosterone. Testosterone is the primary sex steroid produced by the Leydig cells of the testes. Its effects are as follows: stimulates sex drive, maintains secondary sexual characteristics, stimulates growth and secretory activities of the accessory sex glands, maintains spermatogenesis. It is also responsible for embryogenesis of male ducts, systems and external genitalia and subsequent maturation at the time of puberty. Descent of the testes into the scrotum from the abdominal cavity at birth is under control of testosterone. It also promotes the growth of many bodily tissues through anabolic effects. The action of testosterone on androgen-sensitive tissues appears to be mediated by conversion of testosterone to dihydrotestosterone by the target cell. Dihydrotestosterone is the active hormone in the prostate, epididymis and on the tissues to promote growth. The action is mediated by induction of RNA and protein synthesis via androgen receptors, similar to the effects of other steroids on other steroid receptors. Testosterone can also be convened to estradiol in the testes and peripherally. Again, the correct choice is #4, testosterone

Front 415

In oxidative phosphorylation, the energy for the synthesis of ATP is provided by theA. breaking of covalent bonds in glucose moleculesB. creation of carbon dioxide and a metabolic waste productC. formation of GTP from GPDD. movement of hydrogen ions through channels in the respiratory enzymesE. splitting of water molecules into hydrogen and oxygen atoms

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movement of hydrogen ions through channels in the respiratory enzymesThe correct answer is D. Oxidative phosphorylation is the process that produces greater than 90% of the ATP used by the cells in our body. The major steps involved in this process occur within the "electron transport system (ETS)" or "respiratory chain" of the mitochondria. The steps at the end of the electron transport system where ATP is generated are as follows: Along the ETS, the respirafory enzymes continually pump hydrogen ions from the matrix of the mitochondria to the intermembrane space, which creates a large concentration gradient. At the end of the ETS, hydrogen ions pass through channels in the respiratory enzymes along the concentration gradient. As the hydrogen ions pass through these enzymes, the energy created is used to convert ADP to ATP. The breaking of covalent bonds in glucose molecules (choice A), creation of carbon dioxide and a metabolic waste product in the TCA cycle (choice B) and splitting of water molecules into hydrogen and oxygen atoms (choice E) all require energy or do not create energy. The formation of GTP from GPD (choice C) is a process that creates ATP in the TCA cycle (Kreb's cycle).

Front 416

In response to excess water in the body, one would expect to see which of the following physiological changes?A. Decreased glomerular filtration rateB. Decreased permeability of the distal convoluted tubules and collecting ductC. Increased antidiuretic hormone levelsD. Increased permeability of the ascending loop of HenleE. Increased urine osmolality

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Decreased permeability of the distal convoluted tubules and collecting ductThe correct answer is B. When the blood volume increases due to an accumulation of water in the body, the kidneys are responsible for removing the excess fluid. Although both the distal convoluted tubule and collecting tubules are primarily involved in the reabsorption of sodium ions, they can impact the osmolality of urine by increasing or decreasing the reabsorption of water. When there is excess fluid in the body, these two portions of the nephron will decrease their permeability to water; hence, the elimination of fluid in the urine will increase. Deareasing the glomerular filtration rate (choice A) will decrease the amount of water excreted by the kidneys. Antidiuretic hormone (choice C) primarily functions to decrease the elimination of water, through greater reabsorption through the more permeable walls of the collecting tubules. Since the ascending loop of Henle is primarily involved with the reabsorption of ions, increasing its permeability will not increase the elimination of water (choice D). As a general rule, as the urine osmolality increases (urine is more salty), the amount of water in the urine decreases. Therefore, an increased urine osmolality is associated with a decreased excretion of fluid.

Front 417

In response to respiratory alkalosis, which of the following physiological effects will most likely occur?A. The body will retain carbon dioxideB. The kidneys will conserve bicarbonateC. The kidneys will increase the secretion of hydrogen ionsD. The respiratory rate will increaseE. The tidal volume will increase

Back 417

The body will retain carbon dioxideThe correct answer is A. Respiratory alkalosis typically develops when the plasma PC02 levels drop below normal levels. Therefore, when this condition occurs, the body will work to retain carbon dioxide to increase the PC02 levels and correct the alkalosis. If the kidneys were to conserve bicarbonate (choice B) or increase the secretion of hydrogen ions (choice C), the severity of the respiratory alkalosis would increase. Since the primary cause of respiratory alkalosis is hyperventilation and loss of C02, increasing the respiratory rate (choice D) would only worsen the situation. Increasing the tidal volume (choice E) would not affect an individuals respiratory alkalosis.

Front 418

In the catabolism of an amino acid, all of the following are true statements EXCEPTA. Amino acid catabolism requires the coenzyme derivative of vitamin B6 (pyridoxine).B. Deamination results in the generation of ammonia.C. The first step in the catabolism of an amino acid is the removal of the central carbon.D. The liver is the primary site of deaminationE. Transamination attaches the amino group of an amino acid to a keto acid.

Back 418

The first step in the catabolism of an amino acid is the removal of the central carbonThe correct answer is C. The first step in the catabolism of an amino acid is the removal of the amino group, not the central carbon. This process of amino acid catabolism requires the coenzyme derivative of vitamin B6 (pyridoxine) (choice A). The amino group can be removed either by deamination or transamination. Deamination results in the generation of ammonia (choice B), which is then quickly detoxified into urea, which is subsequently excreted in the urine. The liver is the primary site of deamination reactions (choice D). Transamination is a process that attaches the amino group of an amino acid to a keto acid (choice E).

Front 419

In the coagulation phase, which of the following is involved in the common pathway?A. Christmas factorB. FibrinogenC. Hageman factorD. ProaccelerinE. Tissue factor

Back 419

FibrinogenThe correct answer is B. The process of homeostasis aids in the prevention of blood loss through the wall of damaged vessels and establishes a framework for tissue repairs. The common pathway begins when the thromboplastin from both the intrinsic and extrinsic pathways appears in the plasma. After a series of reactions, prompted by these compounds, thrombin completes the coagulation process by converting fibrinogen to fibrin. Christmas factor (choice A), or factor IX, is involved in the intrinsic pathway. Hageman factor (choice C), or factor XII, is involved in the intrinsic pathway and inactivates plasmin. Proaccelerin (choice D), or factor V, and tissue factor (choice E), or factor Ill, are involved with both the extrinsic and intrinsic pathways.

Front 420

In the glycolytic pathway, the substance formed after the enzyme phosphoglucose isomerase exerts its action isA. Fructose-6-phosphateB. Fructose-1,6-biphosphateC. Glucose-6-phosphateD. Glyceraldehyde-3-phosphateE. Pyruvate

Back 420

Fructose-6-phosphateThe correct answer is A. Glycolysis, in summary, is a series of reactions that converts glucose into pyruvate with the concomitant production of ATP. Glycolysis begins when glucose reacts with hexokinase to form the compound glucose- 6-phosphate (choice C). When this compound interacts with the enzyme phosphoglucose isomerase, the fructose-6-phosphate (choice A) is formed. Following the formation of this compound, the enzyme phosphofructokinase will interact with the fructose-6- phosphate to form fructose I ,biphosphate (choice B). When fructose-l,6-biphosphate interacts with aldolase, glyceraldehyde 3-phosphate (choice D) is formed. After a number of enzymatic reactions, the compound phosphoenolpyruvate is formed. When it interacts with pyruvate kinase, pyruvate (choice E) is formed. In the presence of oxygen the pyruvate is converted to acetyl-CoA.

Front 421

In the process known as cotransport all of the following are true EXCEPTA. A carrier protein is requiredB. ATP is NOT requiredC. Molecules can be moved against a concentration gradientD. Only one molecule or ion can be moved through the cell membrane at one timeE. The saturation phenomenon may be observed

Back 421

Only one molecule or ion can be moved through the cell membrane at one timeThe correct answer is D. In secondary active transport or cotransport, the carrier protein (choice A) does not require energy or ATP (choice B). In this process, a secondary active transport protein is able to move one or more ions along a concentration gradient. As one material enters a cell, another is removed, hence the term "co-transport" (thus Choice D is not true and is our answer). However, unlike facilitated diffusion, the carrier proteins in this process are able to move molecules against a concentration gradient (choice C). Since there are a limited number of carrier proteins, when large quantities of the ions or molecules present to the carrier proteins, these proteins may become saturated (choice E).

Front 422

In which of the following conditions might the systolic blood pressure be abnormally high?A. Cardiac shockB. Heart failureC. Anaphylactic shockD. Decreased arterial complianceE. Ventricular fibrillation

Back 422

Decreased arterial complianceThe correct answer is Choice D. Systole is the period of contraction following diastole, a period of relaxation. Systolic and diastolic pressures are often measured by the ausculatory method. In a young adult, the systolic pressure is about 120 mm Hg and about 80 mm Hg for diastolic pressure. Systolic blood pressure may be abnormally high when the arteries become hardened with arteriosclerosis and have decreased compliance (Choice D). Conditions in Choices A, B, C and E will not cause an abnormally high systolic pressure. In these circumstances, the systolic pressure may be lower than normal because the contractility of the heart is compromised.

Front 423

In which of the following parts of the circulatory system is blood pressure the lowest?1. Aorta2. Veins3. Arterioles4. Capillaries5. Large arteries

Back 423

VeinsThe correct choice is #2 veins. Pressure in the circulation is the force applied by the blood against the unit of area of the wall of a blood vessel. It is by convention measured in millimeters of mercury. Blood pressure of 120 mmHg, for example, means that blood exerts the force sufficient to support a vertical column of mercury 120 mm in height. The systolic pressure is the peak of the entire cardiac cycle, occurring early in ventricular systole. The diastolic pressure is the lowest pressure of the entire cardiac cycle, occurring in ventricular diastole. The pulse pressure is the difference between the systolic and diastolic pressure. The venous portion of the circulation returns blood to the heart. They serve as capacitance vessels and at rest store up to 75% of systemic blood volume. Compared to the arterial part of the circulation the venous portion is characterized by much lower pressures and much higher compliances. The normal pressure ranges are as follows: The right atrium has a pressure between 2-5 mmHg. The right ventricle has a pressure between 15-20 mmHg. Pulmonary artery 15-25 mmHg. Left atrium 5- 12 mmHg. Left ventricle 100- 140 mmHg. Aorta 100-140 mmHg. So again, the correct choice to question is #2, veins.

Front 424

In which of the following situations is an osmotic diuresis observed?1. During diabetes mellitus2. During water deprivation3. Following ingestion of starch4. Following injection of Pitressin

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During diabetes mellitusThe correct choice is #1, during diabetes mellitus. Before we answer this question it is important you understand the mechanism of insulin action. Insulin increases the maximum velocity of carrier-mediated glucose transport increased energy-dependent transport of amino acid, increased movement of potassium, leads to hyperpolarization of cells. In adipose tissue it increases the affinity of carriers for glucose. In the liver it may increase amino acid transport, but it is important that you understand that it has no effect on glucose transport in the liver. Insulin causes a decrease in the cyclic AMP levels, which affects enzymes that catalyze reactions involving gluconeogenesis and glycogen breakdown. Insulin increases ribosomal RNA activity, therefore increasing protein synthesis. Glucose is the most important signal promoting insulin secretion by the beta cells of the pancreas. Arginine also stimulates the secretion of insulin. Diabetes mellitus type I, or absent insulinopenia, is a state of inadequate glucose utilization. Inadequate levels of insulin lead to an inability to remove excess glucose from the blood. There is a severe lack of ability to store foodstuffs as glycogen, fat and protein. The response is like starvation, so that there is an increase in gluconeogenesis and, therefore, an increase in the concentration of glucose. Loss of glucose in the urine osmotically brings with it the loss of water. With it comes dehydration. So the correct choice is #l.

Front 425

Ketone bodies are produced as a result ofA. GluconeogenesisB. Glycogen breakdownC. Lipid and amino acid breakdownD. Protein breakdownE. Triglyceride breakdown

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Lipid and amino acid breakdownThe correct answer is C. Ketone bodies are produced as a result of lipid and amino acid breakdown. When these substances break down, acetyl-CoA is generated. As acetyl-CoA levels increase, ketone bodies begin to form. When excessive amounts of ketone bodies are formed, the pathological state known as ketosis can occur. Gluconeogenesis (choice A) and glycogenolysis (glycogen breakdown) occur when glucose is needed for the production of ATP for various cells in the body. Glycogen breakdown (choice B) results in the production of glucose; lactic acid is also produced in this process. When protein is broken down (choice D), amino acids are formed. Triglyceride breakdown (choice E) results in the production of lipids.

Front 426

Lipids are most characteristic of which of the following cellular components?1. Cytoplasm2. Ribosomes3. Membranes4. Chromosomes

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MembranesThe correct choice is #3, the membranes. The cell membrane is selectively permeable and has many transmembrane proteins whose functions are still being investigated. Some transmembrane proteins may function as channels for transport of materials into and out of the phospho-lipid bilayer. All of the other choices listed here are subcellular structures and not composed primarily of lipid. The cytoplasm contains these subcellular structures and is confined by the membrane. So again, the correct choice is #3.

Front 427

Low Density Lipoprotein (LDL) particles get into cells byA. simple diffusion.B. cell-cell fusion.C. active transport.D. facilitated diffusion.E. receptor-mediated endocytosis.

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receptor-mediated endocytosis.The correct answer is Choice E. Low density lipoproteins (LDL) are large spherical particles made up of a core of esterified cholesterol surrounded by a lipid bilayer containing protein. It is the primary source of cholesterol for cells outside of the liver and intestine. LDL are transported into cells by receptor-mediated endocytosis (Choice E). When cholesterol is needed, a cell synthesizes receptor proteins for LDL and inserts them into its plasma membrane. LDL binds to these receptors and is taken up by the cell during endocytosis. When too much free cholesterol is accumulated, the cell shuts off LDL receptor synthesis and thus stops the flow of cholesterol into the cell. Choices A through D do not describe the pathway in which LDL is transported into a cell.

Front 428

MOST fluid reabsorption by the kidney occurs in which of the following?A. Distal tubuleB. Proximal tubuleC. Collecting ductD. Ascending loop of HenleE. Descending loop of Henle

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Proximal tubuleThe correct answer is choice B. The nephron is the functional unit of the kidney. It consists of two main parts. The glomerulus portion through which large amounts of fluid are filtered from the blood, and the tubule portion in which the filtered fluid from the glomerulus is converted into urine. Fluid absorption by the kidney occurs in the tubule portion of the nephron. This section is further divided into segments each with a special function. The proximal tubule (Choice B) has the highest capacity for fluid reabsorption. In fact, most of the fluid reabsorbed by the kidney occurs here. The distal tubule (Choice A) is mainly responsible for reabsorption of ions. It is virtually impermeable to water and urea. The collecting duct (Choice C) is the terminal segment of the nephron tubule system. It reabsorbs less than 10% of filtered water. The ascending loop of Henle (Choice D) is also virtually impermeable to water. It is chiefly concerned with reabsorption of solute. The descending loop of Henle (Choice E) is highly permeable to water and moderately permeable to most solutes. It, however, only reabsorbs about 20% of the filtered water, far less than the proximal tubules.

Front 429

Most heat is lost from the body by which of the following processes?A. ConductionB. ConvectionC. EvaporationD. Insensible perspirationE. Radiation

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RadiationThe correct answer is E. Heat exchange with the environment involves four basic processes: Radiation, conduction, convection, and evaporation. Warm objects, such as the sun or our bodies, will lose heat energy as infrared radiation. Our bodies lose heat energy in the same manner as the sun, except in much smaller amounts. Greater than half the heat lost from our body can be attributed to the process of radiation. Conduction (choice A) is the process where energy is directly transferred through physical contact with another substance. Convection (choice B) is the result of "conductive" heat loss to the air that overlies the body. As the body conducts heat to the air next to the skin, the air warms and rises and is replaced by cool air. Approximately 10-15% of the body's heat is lost through this process. Evaporation (choice C) is a process that changes liquid to a vapor. Insensible perspiration (choice D) is a form of evaporation where heat is lost at a constant rate throughout the day. This form of perspiration accounts for approximately 20% of the body's heat loss.

Front 430

Most muscles in the body can be classified asA. Circular musclesB. Convergent musclesC. Parallel musclesD. Pennate musclesE. Smooth muscles

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Parallel musclesThe correct answer is C. Skeletal muscle is the most common type of muscle found within the human body. Muscle fibers within a skeletal muscle form bundles called fascicles. The muscle fibers within a fascicle organization can be classified as being parallel muscles, circular muscles, convergent muscles and pennate muscles. Since most skeletal muscles are composed of parallel muscles, the majority of the muscles in the body can be classified as being parallel muscles. In a parallel muscle the fascicles are parallel to the long axis of the muscle. In a circular muscle (choice A) or sphincter, the muscle fibers are concentrically arranged around an opening or recess. Circular muscles guard the entrances and exits of internal passageways, such as the digestive and urinary tracts. In a convergent muscle (choice B), the muscle fibers are based over a broad area; however, all the fibers come together at a common attachment site. For example, they may pull on a tendon, a tendinous sheet or a slender band of collagen fibers. In a pennate muscle (choice D), the fascicles form a common angle with the tendon. Smooth muscles (choice E) are not considered to be skeletal muscles; these muscles, for example, line the digestive tract.

Front 431

Neutral fats contain mixtures of one or more fatty acids esterified with1. sterol.2. glycerol.3. lecithin.4. sphingosine.5. alcohols of high molecular weight.

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glycerolThe correct answer is choice 2. Neutral fats are formed when a molecule of glycerol combines with three fatty acids through a dehydration synthesis. Choice 1, sterols, including cholesterol and lanosterol, are steroids and are not chemically closely related to neutral fats. Choice 3, lecithin, is another name for phosphatidylcholine, a phosphoglyceride found in cell membranes. Choice 4, sphingosine, is a molecule which, together with a fatty acid and a polar head group, makes up a sphingolipid which is another lipidtype molecule. Choice 5 is incorrect. The glycerol, which combines with fatty acids, is an alcohol with three OH groups, but it is a low molecular weight substance. So the correct answer to question is choice 2.

Front 432

Neutralization of acids by saliva results mainly from which of the following salivary contents?1. Mucin2. Ammonia3. Carbonate4. Bicarbonate5. Amino Acids

Back 432

BicarbonateThe correct choice is #4, bicarbonate. Saliva is secreted from three pairs of salivary glands: the parotid, submaxillary and sublingual. The average adult secretes 1-2 liters of saliva a day. Saliva is alkaline, which means it has a pH of >7, due to its high concentration of HC03. This helps prevent dental caries by neutralizing any acid produced by bacteria in the oral cavity. Saliva also has elevated concentrations of potassium, amylase, lysozyme, IgA and lactoferrin. The stimulation of parasympathetics and the release of acetylcholine increases the volume of saliva and the concentration of the bicarbonate ion. Stimuli for salivation includes conditioned reflexes, the taste of acid and other tastes, smell, nausea and mechanical stimulation of the oral cavity. So again, the correct choice is #4, bicarbonate.

Front 433

One would expect to see edema in all of the following situations EXCEPTA. The blood hydrostatic pressure in the capillaries increasesB. The heart becomes an insufficient pumpC. The kidneys are unable to produce urineD. The lymphatic vessels become blockedE. The plasma protein concentration in the blood increases

Back 433

The plasma protein concentration in the blood increasesThe correct answer is E. Edema is defined as an abnormal accumulation of interstitial fluid. The underlying problem associated with all types of edema is the disturbance of the normal balance between hydrostatic and osmotic forces at the capillary level. Plasma proteins affect osmotic forces at the capillary level in the following manner: When plasma protein levels increase, fluid is drawn from the interstitial tissue into the capillaries. Conversely, when plasma protein levels decrease, fluid will flow from the capillaries into the interstitial tissue. As the blood hydrostatic pressure in the capillaries increases (choice A) fluids will be forced out of the capillaries. Note: all of the other answer choices either directly or indirectly cause the hydrostatic pressure in the capillaries (or lymphatic vessels) to increase. When the heart becomes an insufficient pump (choice B), as commonly seen in congestive heart failure, blood will begin to "pool" in the capillary system leading to an increased hydrostatic pressure. If the kidneys are unable to produce urine (choice C) the blood volume will increase, leading to an increased hydrostatic pressure. When the lymphatic vessels become blocked (choice D), fluid will move out of the lymph vessels into the interstitial tissue.

Front 434

Over a period of time, a man uses 4 liters of oxygen and produces 3 liters of CO2. What is his RQ for that period?1. 0.752. 1.003. 1.334. 7.00

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0.75The correct choice is #1,0.75. The R.Q. or respiratory quotient is defined as the volume of carbon dioxide produced/volume of oxygen consumed. This is a fairly straightforward problem, since it is not even necessary to convert the units of volume into the same units, since both oxygen and carbon dioxide are in liters. So in this case we have a man producing 3 liters of carbon dioxide and consuming 4 liters of oxygen. Our R.Q. is equal to C02 produced/02 consumed, or 3 liters/4 liters. Liters canceling out, we are left with 314 or 0.75 for the correct choice of #1.

Front 435

Ovulation is triggered by a marked increase in which of the following?A. EstrogenB. EstradiolC. ProgesteroneD. Luteinizing hormoneE. Follicle-stimulating hormone

Back 435

Luteinizing hormoneThe correct answer is Choice D. Ovulation is the first step in the female reproductive cycle when a single ovum is released from an ovarian follicle. It is triggered by a marked increase of luteinizing hormone (Choice D) secreted by the anterior pituitary gland. The luteinizing hormone in turn causes a cascade of effects until the follicle ruptures with the discharge of the ovum. Estrogen, choice A, is incorrect as it has a strong feedback effect in the anterior pituitary gland to maintain low secretory rates of both FSH and LH. Estrogen is in fact used in oral contraceptives to suppress ovulation. Estradiol, Choice B, is one of the three estrogens presents in the human female. It is also an incorrect choice as explained above. Progesterone, Choice C, is also incorrect as it promotes secretory changes of the uterine endometrium in preparation for implantation during the latter part of the reproductive cycle. Follicle stimulating hormone, Choice E, causes growth of the follicles before ovulation, but will not trigger ovulation.

Front 436

Oxygen tension is GREATEST in which of the following blood vessels?A. AortaB. Pulmonary veinC. Pulmonary arteryD. Coronary arteryE. Coronary vein

Back 436

Pulmonary veinThe correct answer is Choice B. Oxygen tension is highest in the pulmonary vein (Choice B). Pulmonary veins contains blood that is richly oxygenated by the lungs on its way to the left atrium of the heart. The vein is unusual as veins are normally oxygen poor. The aorta (Choice A) receives oxygenated blood from the left ventricle and distributes it to various parts of the body. Though the oxygen tension in the aorta is high, it is not as oxygen rich as the pulmonary vein. Pulmonary artery (Choice C) receives oxygen poor blood from the right ventricle on its way to the lungs. Coronary artery and vein (Choices D and E) provide local circulation to the heart muscle itself. They also do not have the greatest oxygen concentrations in the body.

Front 437

Pantothenic acid is an integral part of1. NAD.2. cobalamin.3. folic acid.4. coenzyme A.5. pyridoxine phosphate.

Back 437

coenzyme A.The correct answer is choice 4. Co-enzyme A, involved in fatty acid oxidations, fatty acid syntheses, pyruvate oxidation and other reactions, contains a pantothenic acid group as well as an adenine, a ribose phosphate, and a beta-mercaptoethylamine. Choice 1 , NAD, is involved as a co-enzyme in many oxidation reduction reactions, and is known as nicotinamide-adenine dinucleotide. It contains nicotinamide, adenines, phosphate groups and pyridine. Choice 2, cobalamin, is incorrect. Cobalamin, combined with a cyanide group, forms Vitamin B 12. Cobalamin contains a corrin ring system, a cobalt atom, and a ribonucleotide. Choice 3, folic acid, is incorrect. It contains pteridine, para-aminobenzoic acid and glutamic acid. Folic acid is involved in purine and pyrimidine synthesis and transfers one-carbon groups. Choice 3 is incorrect. Pyridoxine phosphate is a pyridoxine co-enzyme closely related to vitamin B6 especially involved in transamination. It contains a pyridoxine ring and phosphate group. So only choice 4, co-enzyme A, contains a pantothenic acid group, and the correct answer to question is choice 4.

Front 438

Phenylalanine is the precursor essential amino acid of which of the following?A. AsparagineB. CysteineC. GlutamineD. ProlineE. Tyrosine

Back 438

TyrosineThe correct answer is E. The human body is able to synthesize roughly half of the amino acids necessary to build protein. The amino acids that must be supplied in the diet are termed essential, whereas the amino acids that the body is able to synthesize are termed non-essential. The essential amino acids are as follows: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine. The non-essential amino acids are Alanine, Arginine, Asparagine, Aspartate, Cysteine, Glutamate, Glutamine, Glycine, Proline, Serine, and Tyrosine. As noted before, phenylalanine is an essential amino acid in mammals. This amino acid undergoes hydroxylation to one of the non-essential amino acids, tyrosine. This reaction is catalyzed by the enzyme phenylalanine hydroxylase. It is noteworthy that tyrosine is an essential amino acid in individuals lacking this enzyme. Asparagine (choice A) is a member of the "oxaloacetate family"; its immediate precursor is aspartate. The immediate precursor of cysteine (choice B) is serine. Serine is also the precursor of the non-essential amino acid glycine. Glutamine (choice C) proline (choice D) and arginine are produced from glutamate. The synthesis of glutamate occurs by the reductive amination of alpha-ketoglutarate.

Front 439

Platelets play an important role in hemostasis. Which of the following describes this role?1. They convert fibrinogen to fibrin.2. They agglutinate and plug small, ruptured vessels.3. They supply fibrin stabilizing factor.4. They supply proconvertin for thromboplastin activation.

Back 439

They agglutinate and plug small, ruptured vesselsThe correct answer is choice 2, they agglutinate and plug small ruptured vessels. Within seconds after vascular injury platelets, small anuclear circulating blood cell fragments adhere to the site of damage and pile up on one another to provide a mechanical plug that effectively stops bleeding from minor injuries. Clot formation. however, involves a network of fibers of the blood known as fibrin. Choice 1 is incorrect. Prothrombin converts fibrinogen to fibrin. Choice 3 is incorrect. Plasmin released by damaged cells activates fibrinolysis. Choice 4 is incorrect. Fibrin stabilizing factor is part of the fibrinolytic system. Choice 5 is incorrect. Proconvertin Factor VII is a factor in the extrinsic pathway. So the correct answer to question is choice 2.

Front 440

Preganglionic autonomic nerve fibers are exclusively1. somatic.2. adrenergic.3. sympatetic.4. cholinergic.5. parasympathetic.

Back 440

cholinergicThe correct answer is choice 4, cholinergic. Acetylcholine is the transmitter for a) all autonomic preganglionic neurons either sympathetic or parasympathetic b) parasympathetic postganglionic neurons and c) motor neurons of the spinal cord at the neuromuscular junction. Postganglionic sympathetic neurons use norepinephrine as the neurotransmitter. Choice 1, somatic, is incorrect. Somatic refers to the body or peripheral. However, preganglionic autonomic nerve fibers arise in the central nervous system. Choice 2, adrenergic, is incorrect. Only postganglionic sympathetic fibers are adrenergic. Choice 3, sympathetic, is incorrect, as there are both sympathetic and parasympathetic preganglionic fibers. Choice 5, parasympathetic, is incorrect for the same reason as choice 3. There are both sympathetic and parasympathetic preganglionic fibers. so the correct answer to question is choice 4.

Front 441

Prostaglandins are made within cells1. on an RNA template.2. on rough endoplasmic reticulum.3. from methionine.4. from progesterone.5. from polyunsaturated fatty acids.

Back 441

from polyunsaturated fatty acids.The correct choice is #5, from polyunsaturated fatty acids. Prostaglandin synthesis occurs in cell membranes, utilizing polyunsaturated fatty acids. A prostaglandin is a 20-carbon fatty acid which has contained in its structure a 5-carbon ring. The prostaglandins are hormone fine tuners. They are, therefore, not hormones. Some prostaglandins are PGEI, which functions in breakdown of fat; PGE2, which induces delivery, playing a key role in parturition. PGF2-alpha is another prostaglandin. This functions by decreasing the secretion of progesterone. Prostaglandin synthetase is a key enzyme in prostaglandin synthesis. Another name for this enzyme is cyclooxygenase, since it is involved in the formation of the five-membered ring of this 20-carbon compound. The reason I mention cyclooxygenase is that it is important to know that aspirin inhibits the formation of prostaglandins by inhibiting the cyclooxygenase. Prostaglandins exacerbate the inflammation reaction. So again, the correct choice is #5, from polyunsaturated fatty acids.

Front 442

Protein kinase regulate the activities of key enzymes through which of the following?A. OxidationB. HydrolysisC. AcetylationD. PhosphorylationE. Dephosphorylation

Back 442

PhosphorylationThe correct answer is Choice D. Protein kinase when activated by cyclic AMP modulates key enzymes in different cells by phosphorylation (Choice D). In this way, cyclic AMP can influence many cellular processes. For example, protein kinase phosphorylate glycogen synthetase rendering it inactive and phosphorylate phosphorylase kinase rendering it active. So cyclic AMP is a indirectly responsible for stimulation of glycogen breakdown and inhibition of glycogen synthesis. Choices A, B, C and E do not describe the process in which protein kinase exerts its influence

Front 443

Purine bases taken in the human diet in the form of DNA or RNA are mostly1. excreted as urea.2. excreted in the form of uric acid.3. reused and converted to ATP needed as a source of energy.4. broken down to give NH3, and either malonic acid or methylmalonic acid.

Back 443

excreted in the form of uric acid.The correct answer is choice 2. The purine bases are adenine and guanine. When digested, their final breakdown product is uric acid. Nucleic acids are acted on by various nucleases which will split the nucleic acid into either guanine nucleotides or adenine nucleotides. Further degradation leads to guanosine or adenosine, and then eventually xanthine and finally to uric acid. So the correct answer to question is choice 2.

Front 444

Riboflavin is a vitamin that is a constituent of which of the following?A. coenzyme for amino acid metabolismB. coenzyme FADC. coenzyme NADD. decarboxylation reactionsE. prothrombin

Back 444

coenzyme FADThe correct answer is B. Riboflavin is a vitamin that is a constituent of the coenzymes FAD and FMN; deficiencies of this vitamin result in epithelial and mucosal deterioration. Pyridoxine acts as a coenzyme in amino acid and nucleic acid metabolism (choice A). Deficiencies of pyridoxine result in retarded growth, anemia, and various GI disorders. Niacin (nicotinic acid) is a vitamin constituent of the coenzyme NAD (choice C). Deficiencies of niacin result in the development of CNS, GI, epithelial and mucosal deterioration; this condition is known as pellagra. Thiamine is a vitamin that acts as a coenzyme in decarboxylation reactions (choice D). Thiamine deficiency can lead to muscle weakness as well as CNS and cardiovascular problems. Vitamin K or phytonadione is essential for the synthesis of prothrombin (choice E) and other clotting factors in the liver. Specifically the vitamin K dependent clotting factors are Factor II, VII, IX and X. A deficiency of vitamin K results in a variety of bleeding disorders.

Front 445

Secretin functions in digestion of proteins by increasing1. flow of bile.2. secretion of pepsin.3. flow of pancreatic juice.4. secretion of carboxypeptidase.

Back 445

flow of pancreatic juiceThe correct answer is choice 3. Secretin is secreted by the duodenum as food from the stomach enters the duodenum. When secretin reaches the pancreas, it causes the pancreas to secrete pancreatic juice into the duodenum. Pancreatic juice contains enzymes and also raises the pH of the acidic contents leaving the stomach. Choice 1, flow of bile, would be controlled by cholecystokinin, also from the intestine. Choice 2, secretion of pepsin, is controlled by gastrin from the stomach. Secretion of carboxypeptidase is accomplished by the walls of the small intestine. Carboxypeptidase, choice 4, is a protease and its secretion is not controlled by secretin. So the correct answer to question is choice 3.

Front 446

Severe thiamin deficiency will result in the development ofA. beriberiB. pellagraC. pernicious anemiaD. retarded growthE. scurvy

Back 446

beriberiThe correct answer is A. Beriberi is a condition that occurs with thiamin deficiency; this condition is associated with the development of muscle weakness, and CNS and cardiovascular problems, including heart disease. Niacin is a water soluble vitamin. When severe niacin deficiency occurs, there is a good chance that patients will develop CNS, GI, epithelial and mucosal deterioration, otherwise known as pellagra (choice B). Pernicious anemia (choice C) is a type of anemia that occurs with cyanocobalamin deficiency. Retarded growth can occur with deficiencies of pantothenic acid, pyridoxine, and folic acid. Scurvy (choice E) is associated with the development of epithelial and mucosal deterioration; this condition is seen in patients that are vitamin C deficient.

Front 447

Sounds heard during systole in the antecubital space are produced by1. closure of AV valves.2. closure of the aortic valve.3. turbulent blood flow through the artery.4. laminar blood flow through the occluded artery.

Back 447

turbulent blood flow through the artery.The correct answer is choice 3. Let's review the heart sounds briefly. The first sound or lub occurs when the mitral and tricuspid valves, the A-V valves, close just before systole or ventricular pumping. This rules out choice 1 because A-V closure occurs before systole. Closing of the aortic and pulmonic arterial valves constitute the second sound or dub. This occurs just after systole and so it is also incorrect. Sometimes a low third sound can be heard after diastole during ventricular filling. Choice 3 is correct. During systole, blood flows out of the ventricles into the aorta and pulmonary artery. If this flow is turbulent, a sound can be heard. If it is laminar or smooth flow, it is quiet and therefore choice 4 is incorrect. So the correct answer to question is choice 3.

Front 448

Strong stimulation of spindles in the masseter muscle causes1. relaxation of the masseter muscle.2. contraction of the masseter muscle.3. contraction of the digastric muscle.4. no change in mandibular position

Back 448

contraction of the masseter muscle.The correct answer is choice 2. Spindles are muscle stretch receptors. They set up a reflex arc which tends to keep muscles at a physiologic length. If the spindle fibers of the masseter are stimulated by stretching, a reflex contraction will be set up to return the masseter to normal length. Choice 1 is incorrect and opposite. Likewise, choice 4 is incorrect as we do expect a reflex contraction. Choice 3 is incorrect. The masseter is primarily a closing muscle while the digastric is primarily an opening muscle. The reflex contraction caused in the masseter, which is a closing muscle, might induce relaxation or stretching of the opposing digastric, but would not cause the digastric to contract. So the correct answer to question is choice 2.

Front 449

Sympathetic stimulation of the intestinal tract results in all of the following EXCEPTA. Increased intestinal secretionsB. HypomotilityC. Decreased gastric enzyme productionD. Inhibition of smooth muscle contractionsE. Vasoconstriction of blood vessels

Back 449

Increased intestinal secretionsThe correct answer is A. The sympathetic nervous system, when stimulated, leads to the following: Hypomotility, decreased gastric enzyme production, inhibition of smooth muscle contractions, vasoconstriction of blood vessels, and decreased intestinal secretions, not increased intestinal secretions. Remember the sympathetic nervous system prepares the body for "Fight or Flight" by increasing the activity of the organs essential for the response; the intestinal tract is not needed in the "Fight or Flight" response. Conversely, parasympathetic stimulation results in increased motility, blood supply to the gut through vasodilatation of blood vessels and increased gut secretions.

Front 450

Tension on the vocal cords is regulated by which of the following?A. Extrinsic laryngeal musclesB. Extrinsic ligamentsC. Intrinsic laryngeal musclesD. Intrinsic ligamentsE. Vocal folds

Back 450

Intrinsic laryngeal musclesThe correct answer is C. The larynx is composed of two sets of muscles, the intrinsic laryngeal muscles and the extrinsic laryngeal muscles. The intrinsic laryngeal muscles have two primary functions: regulation of the tension in the vocal folds and opening and closing the glottis. The extrinsic laryngeal muscles (choice A) are responsible for positioning and stabilizing the larynx. During swallowing, both sets of extrinsic and intrinsic laryngeal muscles cooperate to prevent food from entering the glottis. The extrinsic ligaments (choice B) attach the thyroid cartilage to the hyoid bone and the cricoid cartilage to the trachea. The intrinsic ligaments (choice D) bind all nine laryngeal cartilages together. The vocal folds (choice E) protect the entrance to the glottis.

Front 451

The air remaining in alveoli at the end of a forced maximal expiration is the1. tidal volume.2. vital capacity.3. residual volume.4. expiratory reserve volume.5. inspiratory reserve volume.

Back 451

residual volumeThe correct choice is #3, residual volume. Let's briefly review the different lung volumes. The tidal volume is the amount of air inspired and expired with every normal breath, which is approximately 500 ml. The inspiratory reserve volume is the extra volume of air that would be inspired over and above the normal tidal volume. The expiratory reserve volume is the extra volume of air that could still be expired beyond the normal tidal volume. The residual volume is the volume of air remaining in the lungs after maximal expiration. Let's discuss lung capacities. The total lung capacity is the maximum volume to which the lungs can be expanded with the greatest possible inspiratory effect. The vital capacity is the maximal expiration following a maximal inspiration, which is the tidal volume plus inspiratory reserve volume plus expiratory reserve volume. The functional residual capacity is the amount of air remaining in the lungs after normal expiration, and the inspiratory capacity is the total amount of air that can be inhaled after a normal expiration. So again, the correct choice to question is #3, residual volume.

Front 452

The cerebral nuclei of the extrapyramidal system are specifically responsible forA. Control of skeletal muscle toneB. Coordination of limb movementsC. Integration of sensory feedbackD. Processing of equilibrium informationE. Processing of visual information

Back 452

Coordination of limb movementsThe correct answer is B. The axons of the pyramidal cells of the motor cortex descend to synapse on lower motor neurons in the brain stem and the spinal cord. Since there are no intervening synapses, the pyramidal system is able to provide rapid commands to the skeletal muscles and various other organs. There are several other centers that can issue somatic motor commands as a result of processing performed at the unconscious, involuntary level. These centers and their associated tracts comprise the extrapyramidal system. The cerebral nuclei primarily control coordination and preparation of limb movements. The red nucleus, located in the mesencephalon, is the component of the extrapyramidal system primarily responsible for controlling skeletal muscle tone (choice A). The cerebellar nuclei, located in the cerebellum, primarily control the "general" coordination of body movements as well as integrating sensory feedback (choice C). The vestibular nuclei, located in the pons and medulla oblongata, process equilibrium sensations (choice D). The superior colliculi, located in the mesencephalon, process visual information (choice E).

Front 453

The destruction of a clot is a normal physiological process that begins with theA. Activation of calcium to produce tissue plasminB. Activation of prothrombin, which initiates the production of thrombinC. Activation of the proenzyme fibrinogen, which initiates the production of fibrinD. Activation of the proenzyme plasminogen, which initiates the production of plasminE. Production of tissue thromboplastin

Back 453

Activation of the proenzyme plasminogen, which initiates the production of plasminThe correct answer is D. Following a traumatic injury, a blood "clot" will form to prevent excessive blood loss and promote healing. As this repair process proceeds, the clot will gradually dissolve. The dissolution of a clot, known as fibrinolysis, begins with the activation of the proenzyme plasminogen, which initiates the production of plasmin. Plasmin is a substance that will begin to "digest" the fibrin strands and erode the foundation of the clot. Activation of plasminogen can occur with tissue plasminogen activator. When introduced into systemic circulation, at therapeutic concentrations, this agent will bind to fibrin in a thrombus and convert the entrapped plasminogen to plasmin, which initiates local fibrinolysis, through the degradation of fibrin matrix of the thrombus. Activation of calcium to produce tissue plasmin (choice A) occurs after the proenzyme plasminogen is activated. Both choices B and C are involved in the common clotting pathway; the activation of prothrombin initiates the production of thrombin. Thrombin activates the proenzyme fibrinogen, which in turn initiates the production of fibrin. The production of tissue thromboplastin (choice E) or Factor III is involved in the extrinsic clotting pathway.

Front 454

The distribution of carbonate within dental enamel follows the same surface to dentinoenamel junction patterns as which of the following?1. Lead2. Calcium3. Fluoride4. Strontium5. None of the above

Back 454

None of the aboveThe correct choice is #5, none of the above. To understand this question you must understand about the development of the enamel prisms. The enamel prism is laid down via the ameloblasts, specifically via the Tomes' processes on the ameloblasts. When the enamel matrix is formed hydroxyapatite crystallites are deposited in the enamel matrix along the long axis oriented perpendicular to the Tomes' process. Maturation of the enamel matrix involves calcification of the enamel matrix, so distribution of calcium, not carbonate, follows the pattern of the enamel matrix which was laid down via the ameloblasts. The enamel prisms are curved nearest to the dento-enamel junction, and therefore calcification will follow this pattern. So again, the correct choice is #5, none of the above.

Front 455

The dominant factor controlling absorption of iron from the gastrointestinal tract is1. excretion of iron in the urine.2. excretion of iron in the stools.3. saturation of mucosal cells with iron.4. concentration of the ferrous iron in bone marrow, spleen and liver.

Back 455

saturation of mucosal cells with iron.The correct choice is #3, saturation of the mucosal cells with iron. Most iron absorption occurs at the proximal small intestine. Iron first binds to a receptor on the brush border membrane and then gets transported into the cell. The iron may then be transported to the blood, complexing with transferrin, while some binds to apoferritin in the cell to form ferritin. With time some of the iron in ferritin is converted to free iron and transported to the blood. However, much is lost upon sloughing of the cells. Other major electrolytes absorbed from the small intestine are sodium, potassium and chloride. Sodium is absorbed via passive diffusion, cotransport, or secondary active transport and cotransport with chloride ion. Again, the correct choice is #3, the mucosal cells must be saturated with iron.

Front 456

The fluid-mosaic model for membrane structure proposes thatA. the outer and inner faces of the membrane are identical.B. peripheral proteins are situated only on the outer face of the plasma membrane.C. integral proteins are associated with the hydrophobic phase of the bilayer.D. both polar and nonpolar ends of membrane phospholipids are within the hydrophobic phase of the bilayer.

Back 456

integral proteins are associated with the hydrophobic phase of the bilayer.The correct answer is Choice C. The fluid-mosaic model for embryological membranes was proposed in 1972. This model suggests that membranes are made up of a bilayer of phospholipid molecules with their hydrophobic tails pointing toward the center of the structure where they interact with the hydrophobic tails of the opposing phospholipid layer. Integral proteins are found scattered in the hydrophobic phase of the bilayer (Choice C). These proteins may extend through the entire thickness of the membrane and they may also move freely within the plane of the phospholipid bilayer. Choice A is incorrect as the outer and inner faces of the membrane are not identical. The inner face as made up of the hydrophobic portion of the phospholipid molecules while the outer face is made up of the hydrophilic portion. Choice B is incorrect since membrane proteins may extend through to the outer face of the membrane but are not situated only on the outer surface. Choice D is also incorrect since the model contends that only the non-polar end of the phospholipid molecule stays within the hydrophobic phase of the bilayer.

Front 457

The gallbladder is caused to contract by the hormone1. gastrin.2. secretin.3. pancreozymin.4. enterogastrone.5. cholecystokinin.

Back 457

cholecystokininThe correct choice is #5, cholecystokinin. The primary role of the gallbladder is bile storage for release during meals when the gallbladder is relaxed. The sphincter of Oddi has low resistance. Approximately 50% of bile is stored, while the remainder enters the duodenum. Contraction begins approximately a half an hour after meals. Contraction is stimulated by acetylcholine (that's the vagocephalic phase of digestion). Hormones which stimulate contraction include cholecystokinin, or CCK, secretin and gastrin. Contraction, however, is seldom complete, being from 51 % to 99% emptying. The gallbladder wall absorbs water and also it absorbs electrolytes. It concentrates cholesterol and absorbs sodium by the electrogenic pump. It also allows for the passive movement of chloride and the passive movement of water. The secretory product, bile, contains water, phospholipid, cholesterol, bile acids and bilirubin.

Front 458

The hormone responsible for decreasing gluconeogenesis in the liver is synthesized in which of the following?A. Adrenal cortexB. Adrenal medullaC. Alpha cells in the pancreasD. Anterior lobe of the pituitaryE. Beta cells in the pancreas

Back 458

Beta cells in the pancreasThe correct answer is E. In humans, insulin is the hormone that promotes fuel storage by decreasing gluconeogenesis in the liver, promoting glycogen deposition in the liver, and decreasing blood glucose levels. Insulin is synthesized in the beta cells in the islets of Langerhans in the pancreas. The release of insulin from the beta cells is stimulated by an increase in the concentration of glucose in the blood. The action of insulin is antagonized by the hormones produced by the other answer choices. The adrenal cortex (choice A) is responsible for the production of cortisol. Both epinephrine and norepinephrine are produced in the adrenal medulla (choice B). Glucagon is synthesized in the alpha cells in the pancreas (choice C). The anterior lobe of the pituitary (choice D) is responsible for the production of growth hormone.

Front 459

The lack of which of the following substances during tooth formation most likely induces enamel hypoplasia?1. Vitamins A and D2. Vitamins C and D3. Vitamins C and K4. Phosphorus and iron5. Calcium and fluoride

Back 459

Vitamins A and DThe correct answer is choice 1, vitamins A and D. Vitamin A is known to be required for the production and maintenance af healthy epithelial tissue and enamel is an epithelial tissue. Vitamin D is produced in the skin by ultraviolet irradiation of 7 dehydrocholesterol. Vitamin D induces synthesis of a protein required for calcium transport and since calcium transport is involved in enamel formation, Vitamin D would be required. In the formation of enamel, many organic and inorganic substances, for example calcium and phosphate, are required. However, even if there are abundant substrate materials, if there is not an adequate amount of vitamin A and D, the formation of enamel will not be adequate. So the correct answer to question is choice 1.

Front 460

The largest amount of body water can be found in which of the following?A. UrineB. Blood plasmaC. lntracellular fluidD. Interstitial fluidE. Stomach and intestines

Back 460

lntracellular fluidThe correct answer is Choice C. The human body is made up of 50 to 60% of water by total body weight. Most of this water is found in intracellular fluid (Choice C) which constitutes approximately 33% of total body weight. The amount of water in urine (Choice A) is variable. It depends on a number of factors, including the amount of fluid intake, and the amount that is reabsorbed. It does not account, however, for the largest amount of body water. Choice B body plasma contains only 4.5% of water by total body weight. Choice D interstitial fluid accounts for approximately 27% of water by weight. It is the source of the second largest quantity of water found in the body. Choice E stomach and intestines also contain a substantial amount of fluid but do not have the largest quantity.

Front 461

The main control over body temperature, located in a portion of the central nervous system, is the1. pons.2. cerebellum.3. hypothalamus.4. medulla oblongata

Back 461

hypothalamusThe correct choice is #3, hypothalamus. The hypothalamus has a multitude of functions. It centrally maintains the homeostasis of the body by integrating autonomic, somatic and endocrine systems. Temperature regulation involves both posterior hypothalamus and anterior hypothalamus. The posterior hypothalamus responds to cold by producing shivering, vasoconstriction of skin vessels, piloerection and discharge of catecholamines. The anterior hypothalamus responds to excessive heat through sweating, panting and vasodilatation of skin vessels. The receptors monitoring body temperature seem to be located primarily in the anterior or preoptic area of the hypothalamus. Other functions of the hypothalamus include the release of corticotropin, thyrotropin, gonadotropin, somatastatin, prolactin and growth hormone releasing factors. These releasing factors in turn regulate the release of the above hormones from the anterior lobe of the pituitary. So again, the correct choice is #3, hypothalamus.

Front 462

The major center in the brain for autonomic nervous system regulation is the1. hypothalamus.2. pituitary.3. cerebral cortex.4. vestibular nuclei.5. floor of the fourth ventricle.

Back 462

hypothalamusThe correct choice is #1, hypothalamus. The autonomic nervous system is defined as the efferent or motor neurons to the viscera, cardiac and smooth muscle and glands. It functions to adjust the amplitude of visceral activity and coordinate activities of different viscera. The central nervous system centers are the hypothalamus and brainstem, especially the reticular formation. They contain the controlling neurons, cell bodies which are the sites of autonomic regulation.

Front 463

The major driving force for formation of a lipid micelle is1. protein-lipid interaction.2. hydrophobic interaction between hydrocarbon tails.3. hydrogen bonding between water molecules of the micellar core.4. electrostatic interaction between the micellar core and polar heads.

Back 463

hydrophobic interaction between hydrocarbon tails.The correct answer is choice 2. Micelles are formed by bile salts or bile acids that are involved in lipid absorption. Bile salts have polar heads and non-polar tails. Polar heads remain outside in contact with the polar water molecules, while the non-polar tails remain on the interior and attach to fatty acid and phospholipid molecules. Thus, the entire micelle is made miscible with water. The driving forces for the formation of micelles are actually two. The first is the interaction of the nonpolar bile salt tail with hydrophobic fatty acids and phospholipids and removal of these hydrophobic groups from the water. The second is the interaction of the polar heads with water. Choice 2 refers to one of these driving forces. Choice 1 is incorrect as proteins are not involved in micelle formation. Choice 3 is incorrect because the micelle core is lipid and hydrophobic, not water. Choice 4 is incorrect as the micelle core is hydrophobic and does not interact with polar heads. So the correct answer to question is choice 2.

Front 464

The major function of serum LDL is to transport which of the following?A. Bile salts from the intestineB. Triglycerides from the intestineC. Free fatty acids from adipose tissueD. cholesterol and phospholipids from peripheral tissuesE. Cholesterol, cholesterol esters, and phospholipids from the liver

Back 464

Cholesterol, cholesterol esters, and phospholipids from the liverThe correct answer is Choice E. Lipoproteins are compounds containing both lipids and proteins. Serum LDL or low density lipoproteins are intermediate-density lipoproteins with a high concentration of cholesterol, moderately high concentration of phospholipids, and minimal amount of triglycerides. Their primary function is to transport their lipid components, cholesterol, cholesterol esters, and phospholipids from the liver to the peripheral tissues (Choice E). Choice A through D are all incorrect since serum LDL does not perform functions described in those choices.

Front 465

The majority of the hydroxyapatite produced in bone occurs when calcium phosphate interacts withA. calcium carbonateB. calcium hydroxideC. fluorideD. magnesiumE. sodium

Back 465

calcium hydroxideThe correct answer is B. Calcium phosphate, Ca3(P04)2. which accounts for approximately two-thirds of the weight of bone. interacts with the calcium hydroxide, Ca(OH)2, to form crystals of hydroxyapatite, Ca10(P04)6(OH)2. As these crystals form, they will incorporate other calcium salts, such as calcium carbonate (choice A), fluoride (choice B), magnesium (choice D) and sodium (choice E).

Front 466

The maximal number of impulses that a nerve fiber can carry is determined by which of the following?1. The intensity of the stimulus2. The diameter of the nerve fiber3. The duration of the absolute refractory period4. The duration of the relative refractory period

Back 466

The duration of the absolute refractory periodThe correct answer is choice 3, the duration of the absolute refractory period. The absolute refractory period is a period during which a second stimulus no matter how strong cannot initiate another impulse and it therefore determines the maximum number of impulses that a nerve fiber can cany. Choice 1, the intensity of the stimulus is incorrect. Stimulus is a current such that the membrane is depolarized to the firing level. Any stimulus at or above the threshold intensity would result in the same action potential with constant amplitude. This is known as the all or none response. Choice 2 is incorrect, the diameter of the nerve fiber. The greater the diameter of a given nerve fiber, the greater its speed of conduction. Choice 4, the duration of the relative refractory period is incorrect. The relative refractory period which immediately follows the absolute refractory period is the phase at which sodium inactivation is ending. At this point, a stronger than normal stimulus can initiate another action potential. So the correct answer to question is choice 3.

Front 467

The nitrogenous product that is excreted in high amounts after prolonged acidosis is1. urea.2. ammonia.3. glutamine.4. creatinine.5. aspartic acid.

Back 467

ammoniaThe correct answer is choice 2. In prolonged acidosis, higher than usual amounts of ammonia are excreted. As ammonia is excreted, hydrogen ions are excreted as well in the combined NH4+ form. This helps to reduce the level of hydrogen ions in the body. Choice 1 is incorrect. Urea is normally the primary nitrogenous waste, but after prolonged acidosis, ammonia excretion is greater than urea excretion. Choice 3 is incorrect. Glutamine is changed to glutamate in tubular cells, forming NH4+ or ammonium ions. However, glutamine itself is not excreted. Creatinine is excreted to a small degree in normal urine and to a greater degree in children and in pregnant women, but is never the chief nitrogenous waste product. So choice 4 is incorrect. Choice 5 is incorrect. Aspartic acid and amino acid is not a major nitrogenous waste. So the correct answer to question is choice 2.

Front 468

The normal delay in sexual development until puberty is attributed to1. lack of effect of sex hormones on somatic tissue.2. failure of the gonads to respond to gonadotrophins.3. inability of the hypophysis to synthesize gonadotrophins.4. lack of hypothalamic stimulation of gonadotrophin release.5. inability of the hypophysis to respond to hypothalamic releasing hormones.

Back 468

lack of hypothalamic stimulation of gonadotrophin releaseThe correct choice is #4, lack of hypothalamic stimulation of gonadotropin release. In explaining this question let's use the female as an example. The hypothalamic pituitary cycle initiates the menstrual cycle of the female. Luteinizing hormone and follicular stimulating hormone initiate development of the ovary. Gonadotropic releasing hormone regulates the release of LH and FSH. Without hypothalamic stimulation of the gonadotropin release the female will remain prepubescent. In males the production of androgenic steroid hormones by Leydig cells and spermatogenesis is regulated by the anterior pituitary secretions, luteinizing hormone and follicle stimulating hormone. The anterior pituitary also is regulated by the hypothalamic secretion of gonadotropic releasing hormone. In prepubertal boys gonadotropin occurs at low levels. By age 10 there are surges in gonadotropin in the sleep and this initiates puberty. Again, the correct choice is #4.

Front 469

The oxygen atoms in a molecule of oxygen are held together byA. a single covalent bondB. a double covalent bondC. a triple covalent bondD. a polar covalent bondE. an ionic bond

Back 469

a double covalent bondThe correct answer is B. Oxygen, with an atomic number of 8, has two electrons in its first energy level and six in its second energy shell. Two oxygen atoms in a molecule of oxygen are stable and held together by a double covalent bond; with the configuration 0=0 or 02. A single covalent bond (choice A) can be found between two hydrogen atoms; with the configuration H-H or H2. A triple covalent bond (choice C) is rarely found; it would be represented with the configuration HCEN. A polar covalent bond (choice D) exists when two elements share electrons and one of the elements has a much stronger affinity for the electrons than the other. For example, in molecules of water, an oxygen atom forms covalent bonds with hydrogen atoms. The oxygen has a much stronger attraction for the shared electrons than the hydrogen atoms. An ionic bond (choice E) is formed by the electrical attraction between atoms that have gained or lost electrons and thus carry an electrical charge. Salts are formed by ionic bonds.

Front 470

The partial pressure of oxygen in arterial blood is lower than that in alveoli. The condition suggested is1. hyperventilation.2. slow blood flow.3. high blood pressure.4. inadequate ventilation.5. thickening of the alveolar membrane.

Back 470

thickening of the alveolar membrane.The correct choice is #5, thickening of the alveolar membrane. The assumption that alveolar partial pressure, or PA02 equals end capillary partial pressure is not strictly true. That is, equilibrium in the alveoli is not complete. The result is an alveolar atrial oxygen gradient. If there is a diffusion disturbance such as thickened alveolar capillary barriers or when we have pulmonary blood flow which is faster, or a low oxygen mixture is inspired, the alveolar arterial oxygen gradient is exaggerated. Equilibrium is approached less and less, and p02 falls. So again, the correct choice is #5, thickening of the alveolar membrane.

Front 471

The postganglionic neurons of the sympathetic nervous system release which of the following neurotransmitters?A. AcetylcholineB. DopamineC. EpinephrineD. NorepinephrineE. Serotonin

Back 471

NorepinephrineThe correct answer is D. The sympathetic and parasympathetic nerve fibers all secrete one of two synaptic neurotransmitters: acetylcholine and/or norepinephrine. The nerve fibers that secrete acetylcholine are termed cholinergic and those that secrete norepinephrine are adrenergic nerve fibers. All the preganglionic neurons in both the parasympathetic and sympathetic nervous systems are cholinergic and release the neurotransmitter acetylcholine. The postganglionic neurons of the sympathetic nervous system release norepinephrine. The postganglionic neurons of the parasympathetic nervous system are also cholinergic; hence, release acetylcholine (choice A). Both dopamine (choice B) and serotonin (choice E) are neurotransmitters primarily located in the brain. Epinephrine (choice C) is a catecholamine that is a potent sympathomimetic stimulator of the alpha and beta receptors throughout the body.

Front 472

The PR interval in an electrocardiogram is an index of the1. length of auricular filling.2. period of isometric relaxation.3. length of auricular contraction.4. conduction time between atria and ventricles.5. period of maximal ejection of ventricular systole.

Back 472

conduction time between atria and ventriclesThe correct answer is choice 4. Let's review the P, Q, R, S, T aspects of the electrocardiogram. The upward P wave is produced by atrial depolarization, the QRS complex by ventricular depolarization, and the ST segment and T wave by ventricular repolarization. So in this case the PR interval is the time from the beginning of depolarization of the atria to the beginning of depolarization of the ventricles. Therefore, it represents the time for the depolarization wave to move from the atria to the ventricles. So choice 4 is our correct answer to question.

Front 473

The preganglionic neurons of both the parasympathetic and sympathetic nervous systems release which of the following?A. AcetylcholineB. DopamineC. EpinephrineD. NorepinephrineE. Serotonin

Back 473

AcetylcholineThe correct answer is A. The sympathetic and parasympathetic nerve fibers all secrete one of two synaptic neurotransmitters: acetylcholine and/or norepinephrine. The nerve fibers that secrete acetylcholine are termed cholinergic; those that secrete norepinephrine are adrenergic nerve fibers. All the preganglionic neurons in both the parasympathetic and sympathetic nervous systems are cholinergic. The postganglionic neurons of the parasympathetic nervous system are also cholinergic; hence, they release acetylcholine. The postganglionic neurons of the sympathetic nervous system mostly release norepinephrine (choice D). Both dopamine (choice B) and serotonin (choice E) are neurotransmitters primarily located in the brain. Epinephrine (choice C) is a catecholamine; it is a potent sympathomimetic stimulator of the alpha and beta receptors throughout the body.

Front 474

The presence of glucose in the urine proves that the patient has1. diabetes mellitus.2. negative nitrogen balance.3. exceeded his renal threshold for glucose.4. excessive damage to a glomerulus of the kidney.

Back 474

exceeded his renal threshold for glucoseThe correct choice is #3, exceeded his renal threshold for glucose. Most solutes appearing in the glomerular filtrate are reabsorbed. The maximum rate of reabsorption for a given solute is defined as its maximum tubular resorptive capacity, or Tm Glucose has a given value for Tm. Normally, all filtered glucose is resorbed. Thus, normally it does not show up in the urine. The filtration load of glucose is directly proportional to the plasma glucose concentration. When T, or maximum tubular resorptive capacity is exceeded glucose is excreted. At this point the tubules are absorbing to their maximum, and any extra glucose spills into the urine. The presence of glucose in the urine does not prove the patient has diabetes mellitus, since other states may induce glucose in the urine. Negative nitrogen balance indicates starvation and may show ketonuria, and the appearance of glucose in the urine does not damage the glomerulus, so again, the correct choice is #3, exceeded his renal threshold for glucose.

Front 475

The primary determinant of the resting membrane potential in a neuron isA. intracellular negatively charged chloride ionsB. extracellular negatively charged chloride ionsC. membrane permeability to calciumD. membrane permeability to potassiumE. membrane permeability to sodium

Back 475

membrane permeability to potassiumThe correct answer is D. With respect to the resting membrane in a neuron, the primary determinant of this value is related to the electrochemical gradient of the neuron. This gradient is described as the sum of the chemical and electrical forces across the cell membrane. This resting membrane potential for a given neuron is primarily a reflection of the membrane permeability to the potassium ions. In.other words, the primary determinant of the resting membrane potential in a neuron is membrane permeability to potassium. Although the electrochemical gradient for sodium ions is very large, sodium permeability is small; therefore, sodium ions have a small effect on the normal resting membrane potential (choice E). Sodium ions are primarily attracted by excess negative charges inside of the cell, such as intracellular negatively charged chlorine ions (choice A) and intracellular negatively charged chloride ions (choice B). Hence, these two factors will have a minimal effect on the resting membrane potential. Calcium (choice C) has no effect on the resting membrane potential.

Front 476

The primary link between the nervous and endocrine system is theA. CerebellumB. CerebrumC. HypothalamusD. MesencephalonE. Pons

Back 476

HypothalamusThe correct answer is C. The walls of the diencephalon are composed of the left and right thalamus. A narrow stalk, the infundibulum, connects the floor of the diencephalon, or hypothalamus, to the pituitary gland, which is a component of the endocrine system. The hypothalamus contains various centers involved with emotions, autonomic function and hormone production. The hypothalamus is the primary link between the nervous and endocrine system. The cerebellum (choice A) adjusts voluntary and involuntary motor activities as well as comparing incoming sensory information with anticipated sensations. Conscious thought processes, sensations, intellectual functions, memory storage and retrieval and complex motor actions originate in the cerebrum (choice B). The mesencephalon (choice D) is the center responsible for processing visual and auditory information. The pons (choice E) connects the cerebellum to the brain stem. It also contains nuclei involved with somatic and visceral motor control.

Front 477

The process of chewing food is associated with which of the following movements?A. AbductionB. ElevationC. FlexionD. OppositionE. Protraction

Back 477

ElevationBy definition, elevation occurs when a structure moves in a superior direction. Conversely, depression occurs when a structure moves in a inferior direction. For example, one depresses the mandible when the mouth opens and elevates the mandible upon closing the mouth. In other words, the process of chewing is a repetitive cycle of depressing and elevating the mandible. Abduction (choice A) is the movement away from the longitudinal axis of the body. For example, swinging the right arm to the side. Flexion (choice C) is described as a movement in the anteriorlposterior plane that decreases the angle between the articulating extremities. For example, flexion of the biceps. Opposition (choice D) is the placement of the thumb opposite to the fingers that allows the hand to grasp and hold various objects. Protraction (choice E) is described as the movement of a given part of the body anteriorly in a horizontal plane; the grasping of ones upper lip with their lower teeth is a protracting movement.

Front 478

The process of deamination produces which of the following?A. Acetyl-CoAB. AmmoniaC. Keto acidsD. UreaE. Uric acid

Back 478

AmmoniaThe correct answer is B. Amino acids can be catabolized in one of two processes: Deamination or transamination. Deamination is a process that is performed in the preparation of an amino acid for breakdown in the TCA cycle. In deamination, an amino group is removed and ammonia is generated. Since the ammonia produced is a toxic substance, the liver immediately metabolizes the ammonia molecule to urea (choice D), which is a relatively non-toxic, water-soluble compound that is excreted in the urine. Acetyl-CoA (choice B) is produced by the breakdown of pyruvic acid; an acetyl-group is added to these by-products to produce acetyl-CoA. In the process of transamination, the amino group of a given amino acid is transformed to a keto acid (choice C). A keto acid resembles an amino acid except that the second carbon is bound to an oxygen rather than an amino group. Uric acid (choice E) is another non-toxic waste product that is produced when either DNA or RNA is catabolized during the "breakdown" of a cell.

Front 479

The second heart sound is related to1. excitation of atria.2. opening of AV valves.3. closure of AV valves.4. opening of aortic valves.5. closure of aortic valves.

Back 479

closure of aortic valvesThe correct choice is #5, closure of the aortic valves. Let's discuss the heart sounds. S1, or the first heart sound, is synchronous with mitral and tricuspid valve closure. Its intensity is a clinically useful sign. S1 intensity varies inversely with the PR interval on the ECG. The shorter the P-R interval the louder S1. In mitral stenosis the absence of a loud S1 is an important sign suggesting a rigid, heavily-calcified and immobile mitral valve. The second heart sound is called S2. It is synchronous with aortic and pulmonary valve closure. Its intensity also is a clinically useful sign. The third heart sound, S3, or ventricular gallop, occurs in early diastole. It represents vibrations of the left ventricular structures and blood mass as the rapid inflow of blood is limited to the left ventricular diastolic expansion. S3 is a normal sound in children and young adults. In adults, however, over the age of 30 or 35 years, it represents significant global ventricular dysfunction and is frequently associated with ventricular dilatation. It can also be present in severe anemia, thyrotoxicosis and mitral regurgitation. The fourth heart sound is S4. This is atrial gallop. It occurs after atrial contraction and before S1. Again, the correct choice is #5, closure of the aortic valves.

Front 480

The second step in glycolysis involves the formation ofA. Dihdyroxyacetone phosphateB. Fructose-l,6-bisphosphateC. Glucose-6-phsophateD. Phosphoenolpyruvic acidE. Pyruvic aci

Back 480

Fructose-l,6-bisphosphateThe correct answer is B. In summary, glycolysis breaks down a six carbon glucose molecule into two three carbon molecules of Pyruvic acid. This process involves a series of enzymatic steps. The second step in glycolysis involves the formation of Fructose-l,6-bisphosphate. The entire glycolysis pathway is as follows: Glucose Glucose-6-phsophate -> Fructose-1.6-bisphosphate -> Dihdyroxyacetone phosphate -> Glyceraldehyde 3- phosphate -> 1,3 Biphosphoglyceric acid -> 3- Phosphoglyceric acid -> Phosphoenolpyruvic acid -> Pyruvic acid.

Front 481

The sensory organs concerned with maintenance of skeletal muscle tonus are1. muscle spindles.2. gamma efferents.3. pacinian corpuscles.4. golgi tendon organs

Back 481

muscle spindlesThe correct choice is # 1 , muscle spindles. Within muscles there are specialized receptors, the muscle spindles and Golgi tendon organs. The muscle spindles function when the muscles are stretched. A good example of this is tapping on the patellar tendon. This stretching causes a volley of impulses in the primary endings which synapse directly on the alpha motor neurons, innervating the extrafusal fibers of the muscle in which the spindle is imbedded. Thus, we elicit a contraction of the quadriceps muscles when we tap on the patellar tendon, and obtain the familiar knee jerk reflex. So again, the correct choice to question is #1, muscle spindles.

Front 482

The smooth endoplasmic reticulum is primarily responsible for which of the following?A. Control of metabolismB. Distribution of materials by diffusionC. Lipid and carbohydrate synthesisD. Neutralization of toxic compoundsE. Secretory protein synthesis

Back 482

Lipid and carbohydrate synthesisThe correct answer is C. With respect to basic cell physiology, the synthesis of both lipids and carbohydrates occurs in the smooth endoplasmic reticulum. Control of metabolism (choice A) is the responsibility of the nucleus of the cell. In addition, the nucleus is also responsible for storage and processing genetic information and controlling protein synthesis. The cytosol of the cell is responsible for the distribution of materials by diffusion (choice B). Peroxisomes are intracellular compounds that contain degradative enzymes and are primarily responsible for the neutralization of toxic compounds. The synthesis of secretory proteins (choice E) occurs in the rough endoplasmic reticulum. Note, protein synthesis, in general, is the responsibility of the ribosomes.

Front 483

The spinal cord is the only structure in the central nervous system necessary for which of the following body functions?1. Respiration2. Simple reflex3. Temperature regulation4. Coordinated muscle mavement

Back 483

Simple reflexThe correct answer is choice 2. Simple reflex arcs involve a receptor and afferent neurons which take impulses to the spinal cord, possibly an intervening connecting neuron within the spinal cord, and an efferent neuron to the effector muscle or gland. Thus, in a reflex, the only CNS or central nervous system section involved is the spinal cord. In other words, the brain is not involved in the reflex arc. The brain is involved in choice 1, respiration, as the respiratory control center is located in the medulla. The brain is also involved in choice 3, as the hypothalamus primarily controls the temperature regulation. Coordinated muscle movement, choice 4, is controlled by the cerebellum of the brain. So the correct answer to question is choice 2.

Front 484

The tone of the masseter muscle is maintained by the1. flexor reflex.2. stretch reflex.3. crossed-extensor reflex.4. continuous production of metabolic products.

Back 484

stretch reflexThe correct choice is #2, stretch reflex. The stretch reflex, or myotactic or tendon jerk reflex, is a fast reflex. It involves the stretch of the annulospiral endings to initiate the muscle contraction. The best example of this is the knee jerk reflex. In the masseter, however, this reflex involves muscle tone, which involves a continuous stretch reflex. This tone helps prepare the muscle for movement. Without the stretch reflex the muscle would not be optimally effective. It would be flaccid and inoperable. The annulospiral endings are muscle spindle, primary endings, and 1A fibers come from them. They have a diameter of 12-20 microns and a conduction velocity of 75-125 m/sec. So again, the correct choice to question is #2, stretch reflex.

Front 485

The two most important skeletal elements generally used to determine sex and age areA. Bone thickness and vertebrae curvatureB. Bone weight and bone markingsC. Condition of teeth and muscular massD. Presence and percentage of muscular and fatty tissueE. Teeth and healed fractures

Back 485

Bone weight and bone markingsThe correct answer is B. A study of a human skeleton can reveal important information about an individual. For example, the two most important skeletal elements generally used to determine sex and age are bone weight and bone markings. With respect to the sex of an individual, one can examine the skull. The skull of a male, as compared to a female, will have the following characteristics: The general appearance will be rougher and heavier, the forehead tends to slope, the sinuses are larger, the cranium is around 10% larger, the mandible is larger and robust and the teeth are typically larger. The actual weight of all male bones is often larger to support a bigger mass. Fuhthermore, bone markings are more prominent on all male bones. As years pass, there is a reduction in the size and roughness of bone markings. Furthermore, the weight of a given bone will also decrease. Therefore, one can see that the two most important skeletal elements generally used to determine sex and age are bone weight and bone markings. Regarding choice A, the thickness of "similar" bones in males and females can be closely related and vertebrae curvature increases with age only. The condition of teeth and muscular mass (choice C) are good indicators of a persons general health and exercise habits. The presence and percentage of muscular and fatty tissue (choice C) will depend on an individuals exercise habits, not primarily their sex or age. Looking at a person's teeth and healed fractures (choice E) will show information about an individuals medical history.

Front 486

The type of articulation found between the temporal bone and the mandible can best be described as a (an)A. Ellipsoidal diarthrosisB. Gliding diarthrosisC. Hinge diarthrosisD. Pivot diarthrosisE. Synarthrosis (gomphosis)

Back 486

Hinge diarthrosisThe correct answer is C. The type of articulation found between the temporal bone and the mandible, otherwise known as the temporomandibular joint, can best be described as a hinge diarthrosis since it allows for elevation and depression of the jaw. An ellipsoidal diarthrosis (choice A) is a type of articulation that has an oval articular face that rests within a depression on the opposing surface, which allows angular movement in two planes, along or across the length of the oval. An example of an ellipsoidal diarthrosis would be the articulation found between the occipital bone and the atlas. A gliding diarthrosis (choice B) is a type of articulation that has flattened or slightly curved faces that slide across one another. Examples of this type of diarthrosis would be the articulations between the thoracic vertebrae and ribs. An example of a pivot diarthrosis (choice D) would be the articulation between the axis and the atlas, since a pivot diarthrosis allows for rotation. An example of a synarthrosis (gomphosis) (choice E) would be the articulation found between the maxilla and the upper teeth as well as the mandible and the lower teeth. Movement does not occur with this type of articulation.

Front 487

Thyroid secretion is stimulated by1. hypoxia.2. propylthiouracil.3. exogenous thyroid hormone.4. high serum iodide concentration.5. prolonged exposure to a cold environment.6. prolonged exposure to a warm environment.

Back 487

prolonged exposure to a cold environment.The correct choice is #5, prolonged exposure to a cold environment. There are two forms of thyroid hormone, T3, triiodothyronine and T4, thyroxin. The thyroid hormones travel in the blood, largely bound to plasma proteins in equilibrium with free hormones. Most of the T3 and T4 is bound to thyroxine binding globulin. T3 is more active, but present at much lower plasma levels than T4. Under thyroid stimulating hormone stimulation the apical membrane of the thyroid follicles undergo marked development of the microvilli projecting into the colloid. The epithelial cell microvilli engulf peripheral colloid from the periphery of the follicles. Phagocytic vacuoles containing colloids fuse with lysosomes, and lysosomal proteases break down the thyroglobulin into small peptides, which include T3 and T4. Thyroid hormones are essential to survival in the cold. Normal animals quickly adapt to increase their oxygen consumption, catecholamines and increase muscular activity. These are the direct agents of the adaptation, and T3 and T4 are permissive to the actions of catecholamines. So again, the correct choice to question is 5, prolonged exposure to a cold environment.

Front 488

Tropic hormone releasing factors produced in the hypothalamus are transported into the anterior pituitary through1. nerve impulses.2. the ultrashort feedback mechanism.3. the peripheral circulatory system.4. the microcirculatory portal system.5. long nerve fibers or duas that also transport neurophysins.

Back 488

the microcirculatory portal system.The correct answer is choice 4. Tropic hormone releasing factors are chemicals made in the hypothalamus which act on the anterior pituitary to cause release of tropic hormones. For example, thyroid stimulating hormone releasing factor will be secreted by the hypothalamus, travel in a portal circulation, enter the anterior pituitary and cause that gland to secrete thyroid-stimulating hormone or TSH which will then stimulate the thyroid to release thyroxin. So our correct answer is choice 4. In a portal circulation, one bed of capillaries is connected to another bed of capillaries by a vein. The other main portal system in the body is the hepatic portal systenl in which a capillary bed in the intestine is connected to another capillary bed in the liver by the hepatic portal vein. In the other choices, we should note that neurophysins in choice 5 are sections of precursor molecules of oxytocin and vasopressin which are posterior pituitary hormones produced in the hypothalamus. They are not related to releasing factors. The neurophysins are removed and the active hormone remains. So the correct answer to question is choice 4.

Front 489

Twiddling your thumbs during a dental physiology lecture demonstrates the action that occurs atA. Ball-and-socket jointsB. Ellipsoidal jointsC. Gliding jointsD. Hinge jointsE. Saddle joints

Back 489

Saddle jointsThe correct answer is E. Saddle joints have articular faces that resemble "saddles". Each face is concave at one axis and convex on the other axis. This arrangement permits angular motion, including circumduction; however, rotation is prevented. The carpometacarpal joint at the base of the thumb is a prime example of a saddle joint; twiddling your thumbs during a dental physiology lecture demonstrates the action that can occur at this joint. Ball-and-socket joints (choice A) have a round head at one end that rests within a cup-shaped depression in another. All combinations of movements can be performed at this joint. Prime examples of ball-and- socket joints would be at the hip and shoulder. Ellipsoidal joints (choice B) have an oval articular face that rests within a depression on the opposing surface, which allows angular movement in two planes, along or across the length of the oval. These joints connect the fingers and toes with the metacarpals and metatarsals, respectively. Gliding joints (choice C) have flattened or slightly curved faces that slide across one another. Although rotation is theoretically possible, ligaments usually prevent or restrict such movements. These joints are at the ends of the clavicles, for example. Hinge joints (choice D) permit angular movement in a single plane, much in the same way as opening and closing a door on a hinge. Prime examples of hinge joints include the elbow and knee.

Front 490

Two atoms are considered isotopic if1. their nuclei contain the same number of neutrons.2. their atomic numbers are the same, but their mass numbers differ.3. their mass numbers are the same, but their atomic numbers differ.4. one is a beta emitter, and the other an alpha emitter.

Back 490

their atomic numbers are the same, but their mass numbers differ.The correct answer is #2, their atomic numbers are the same but their mass numbers are different. This is a simple definition type question from general chemistry. The atomic number, as you may recall, is the number of protons in the nucleus of an atom. Isotopes have the same number of protons bur a different number of neutrons. The number of protons plus neutrons of an atom is referred to as the mass number of the atom. If two atoms are isotopes they therefore have different mass numbers. since mass number equals number of protons plus the number of neutrons. If the number of protons is the same and the number of neutrons is different the number of protons plus the number of neutrons will be different, or the mass number will be different. So the correct choice is #2, their atomic numbers are the same but their mass numbers are different.

Front 491

Vascular resistance is directly related to all of the following EXCEPTA. The amount of friction in the blood vesselsB. The diameter of the blood vesselC. The length of the blood vesselD. The viscosity of the bloodE. The volume of blood in the body

Back 491

The volume of blood in the bodyThe correct answer is E. Resistance is defined as any force that opposes movement. The most important component in vascular resistance is the friction caused between the blood and the vessel walls, which is related to the viscosity of the blood as well as the length and diameter of the blood vessel itself. Although the volume of blood in the blood may impact vascular resistance, it does not directly oppose blood flow. As a general rule, vascular resistance and friction (choice A) will increase when the following occur; the diameter of the vessel decreases (choice B) and/or the length of the vessel increases (choice C). Furthermore, as the viscosity of the blood increases (choice D), the resistance will increase as well; remember, syrup flows slower than water.

Front 492

Vascular smooth muscle relaxes in response toA. hyperoxia.B. adenosine.C. vasopressin.D. angiotensin.D. norepinephrine

Back 492

adenosineThe correct answer is Choice B. Of the following substances, only adenosine (Choice B) has a vasodilator effect on blood vessel smooth muscles. It is released from the tissue in response to oxygen deficiency causing increased blood flow and oxygen concentration. Choice A hyperoxia, or an increased oxygen content in body tissues, will cause a local vasoconstriction in the blood vessels and not vasodilation. Choice C vasopressin, or antidiuretic hormone, is mainly responsible for the retention of water in the body. In large concentrations, it will cause constriction of the blood vessels and elevate blood pressure. Choice D angiotensin is a powerful vasoconstrictor. Its primary role is to increase the total peripheral resistance in regulation of arterial pressure. Choice E norepinephrine is released by the sympathetic nerve endings during stress or exercise. Norepinephrine stimulates the veins and arterioles by constriction of these vessels.

Front 493

Visual purple, rhodopsin, is usually formed in the1. lens.2. liver.3. retina.4. adrenals.5. vitreous humor.

Back 493

retinaThe correct choice is #3, the retina. Rhodopsin is a light-sensitive pigment found in the retina. Rhodopsin is formed by the combination of opsin, a protein, with vitamin A aldehyde. Vitamin A aldehyde is also referred to as retinal. Retinal is formed by the oxidation of vitamin A, or retinol. Retinol is preformed vitamin A found in liver, whole milk, eggs and fish oils. Humans intake pro-vitamin A from plants and preformed vitamin A from animals. Beta carotene is the principal dietary source of pro-vitamin A. It is found in yellow and orange vegetables. One molecule of beta carotene is cleaved in the intestinal mucosa into two molecules of retinol, or vitamin A. Again, the correct choice is #3, retina.

Front 494

Vitamin A functions to1. prevent pellagra.2. promote absorption of calcium.3. promote differentiation of epithelial cells.4. maintain the integrity of connective tissues.

Back 494

promote differentiation of epithelial cellsThe correct answer is choice 3. Vitamin A is a constituent of visual pigments and maintains epithelial tissues by promoting differentiation. Deficiency of vitamin A is signalled by night blindness and dry skin. Choice 1 is incorrect. Pellagra is caused by niacin deficiency. Choice 2 is incorrect. Vitamin D increases intestinal absorption of calcium and phosphorous. Choice 4 is incorrect. Vitamin C is associated with maintaining normal intercellular materials such as collagen in bone, cartilage and dentin. So our correct answer to question is choice 3.

Front 495

What type of muscle contraction occurs when both ends of the muscle are fixed and no change in length occurs during the contraction, but the tension increases?A. Concentric contractionB. Dynamic contractionC. Eccentric contractionD. Isometric contractionE. Isotonic contraction

Back 495

Isometric contractionThe correct answer is D. An isometric contraction occurs when both ends of the muscle are fixed and no change in length occurs during the contraction, but the tension increases. A concentric contraction (choice A) is a type of dynamic contraction where the muscle fibers shorten and the tension on the muscle increases. A dynamic contraction (choice B) includes both concentric and eccentric types of contractions. In general, a dynamic contraction results in the change in length of the muscle with a corresponding change in tension on that muscle. An eccentric contraction (choice C) is a type of dynamic contraction where the muscle fiber lengthens and the tension on the muscle increases. An isotonic contraction (choice E) occurs when a muscle shortens against a fixed load while the tension on that muscle remains constant.

Front 496

Voluntary control of the muscles involved in the process of mastication is provided by which of the following?A. Afferent nervous systemB. Autonomic nervous systemC. Parasympathetic nervous systemD. Somatic nervous systemE. Sympathetic nervous system

Back 496

Somatic nervous systemThe correct answer is D. The somatic nervous system provides voluntary control over all skeletal muscle contractions. Therefore, voluntary control of the muscles involved in the process of mastication would be provided by the somatic nervous system. The afferent nervous system (choice A) is primarily involved with bringing sensory information to the CNS from peripheral organs and tissues. The autonomic nervous system (choice B) is responsible for providing autonomic, involuntary regulation of cardiac muscle, smooth muscle and glandular activity. The autonomic nervous system contains both the parasympathetic (choice C) and the sympathetic (choice E) nervous systems. Both of these divisions of the autonomic nervous are antagonistic to one another.

Front 497

When a muscle is producing peak tension during rapid cycles of contraction and relaxation, it is said to be inA. Complete tetanusB. Incomplete tetanusC. TreppeD. Wave summation

Back 497

Incomplete tetanusThe correct answer is B. Since there is no mechanism to regulate the amount of tension produced in a given muscle contraction, the muscle fiber is either producing tension or is relaxed. This feature is known as the all- or-none principle. Therefore, the amount of tension produced by a skeletal muscle as a whole is determined by both the frequency of stimulation and the number of muscle fibers stimulated. With these principles in mind, the following definitions can be applied: When a muscle is producing peak tension during rapid cycles of contraction and relaxation, it is said to be in incomplete tetanus. Complete tetanus (choice A) occurs when a muscle is stimulated so frequently that the relaxation phase is completely eliminated. Recruitment (choice C) occurs when there is a smooth but steady increase in the muscle tension that is produced by increasing the number of active motor units. Treppe, (choice D) is a situation where a muscle is stimulated repeatedly for several seconds with a constant stimulus; the amount of tension produced then gradually increases to a maximum. Wave summation (choice E) occurs when a second stimulus arrives before the relaxation phase has ended and a second, more powerful, contraction occurs.

Front 498

When an individual is administered large amounts of glucocorticoids, such as prednisone, a condition similar to one of the following may result. The patients clinical appearance would be most similar toA. Addison's diseaseB. Adrenogenital syndromeC. Cushing's syndromeD. MyxedemaE. Primary Aldosteronism

Back 498

Cushing's syndromeThe correct answer is C. The Cushing's syndrome is caused by a hypersecretion of cortisol by the adrenal cortex. Cortisol is glucocorticoid similar to prednisone. Therefore, if one were administered large amounts of prednisone for an extended period of time, a Cushing's-like syndrome could result. Cushing's syndrome is characterized by an increased fat deposition in the thoracic region, an edematous appearance of the face, as well as the development of acne and hirsutism. Addison's disease (choice A) results from the failure of the adrenal cortex to produce adrenocortical hormones, resulting in glucocorticoid and mineralocorticoid deficiency. Loss of cortisol (a glucocorticoid) secretion results in the depression of many metabolic functions and decreases one's ability to tolerate various stressors. Adrenogenital syndrome (choice B) is the result of excessive production of androgens, leading to premature masculinizing effects in young males. Myxedema (choice D) is caused by a lack of thyroid function. Patients typically present with swelling under the eyes as well as swelling of the face. Primary Aldosteronism,(choice E), is caused by a hypersecretion of aldosterone leading to hypokalemia, which can eventually lead to periods of muscle paralysis.

Front 499

When an individual quickly rises from a prone position, one would expect to seeA. Heart rate decreaseB. The cardiostimulatory center in the medulla become less excitedC. The carotid baroreceptors become inhibitedD. Vasoconstriction of the peripheral blood vesselsE. Venous return increase

Back 499

Vasoconstriction of the peripheral blood vesselsThe correct answer is D. When a person rises from a prone position, there will typically be a "pooling" of blood in the venous system. In an effort to maintain uniform blood pressures, the carotid baroreceptors, when stimulated by a decrease in blood pressure, will initiate the following: There will be widespread vasoconstriction of the peripheral blood vessels. The net effect will be a shunting of blood to the internal organs and a decreased venous return (choice E). Also, when the carotid baroreceptors are stimulated (choice B), the heart rate will increase (choice A) due to stimulation of the cardiostimulatory center in the adrenal medulla (choice C).

Front 500

When are nerve fibers hypoexcitable?1. During resting potential2. At the firing level3. During local depolarization4. During negative after-potential5. During positive after-potential

Back 500

During positive after-potentialThe correct answer is choice 5. At certain times or under certain conditions, nerve cells may become hypoexcitable; that is, the nerve cell becomes more difficult to stimulate in order to initiate an action potential. Let's look at our choices one at a time. Choice 1, during resting potential, the neuron is at its normal state of excitability, being neither hyper nor hypoexcitable. Choice 2, when nerve fibers are at the firing level or at the point of initiating an action potential, any further stimulation will cause the action potential to occur, so they would not be hypoexcitable at this point. Choice 3 is incorrect. When a neuron experiences a local depolarization response, a depolarization occurs which is strong enough to cause changes in the membrane, but not strong enough to cause an action potential. However, further depolarization may cause the action potential to occur. In this way, the neuron can be viewed as perhaps hyperexcitable, but certainly not hypoexcitable. Choice 4 is incorrect. Following an action potential, a refractory period occurs during which the neuron cannot be stimulated again. Following this period, a brief negative after-potential will occur, during which the neuron is hyperexcitable. Following this period, a positive after-potential will occur, during which the neuron is slightly hypoexcitable. Later, the neuron will return to its normal level of excitability. So the correct answer to question is choice 5.

Front 501

When the blood supply to the dermis decreases and the sweat glands become less active, as seen in the elderly, which of the following factors would be affected the most?A. The ability to fight infectionB. The ability to produce vitamin DC. The ability to repair itselfD. The ability to thermoregulateE. The skin will begin to wrinkle

Back 501

The ability to thermoregulateThe correct answer is D. The skin is a highly complex organ that has many different physiological functions. As individuals age, the skin begins to lose its ability to perform each of these specialized functions. In the elderly, the blood flow to the dermis begins to decrease. Furthermore, glandular activity decreases. When the blood supply to the dermis decreases and the sweat glands become less active, the individual is less able to lose body heat. Therefore, increased physical exertion can lead to extremely high body temperatures. The decreased ability of the skin to fight infection in the elderly (choice A) is related to the decreased number of Langerhans cells and the thinning of the germinative cell layer. A decreased ability to produce vitamin D (choice B) is a normal part of the aging process. This decreased production contributes to a reduction of calcium levels eventually leading to muscle weakness and decreased bone density. The thinning of the epidermis and the loss of elasticity of epidermis contribute to the decreased ability of the skin to repair itself (choice C) as in increased "wrinkling" (choice E) of the skin.

Front 502

When the pH of the extracellular fluid decreases, the kidney will compensate byA. Excreting more bicarbonate ionsB. Excreting more sodium ionsC. Increasing the urine pHD. Reabsorbing less waterE. Retaining more potassium ions

Back 502

Retaining more potassium ionsThe correct answer is E. Although the buffer system in the body is able to regulate the blood pH during normal circumstances, the kidneys may need to aid in the regulation of the blood pH when this system becomes overwhelmed. When the pH of the extracellular fluid declines, the following will occur with respect to potassium: Hydrogen ions will move into the intracellular fluid in exchange for potassium. Furthermore, the kidneys will decrease the elimination of potassium because hydrogen ions are being eliminated in the urine instead of potassium. It is important to note that both of the previously mentioned factors can lead to severe hyperkalemia. In addition to the removal of hydrogen ions, the kidneys will decrease the elimination of bicarbonate ions (choice A), sodium ions (choice B) and water (choice D). In a situation where the extracellular fluid pH is acidic, the kidneys will compensate by acidifying the urine by excreting more hydrogen ions (choice C).

Front 503

When the ventricle of the heart contracts, the stimulus for the contraction comes directly from which of the following?A. Atrial muscleB. AV nodeC. His-bundlesD. Purkinje fibersE. SA node

Back 503

Purkinje fibersThe correct answer is D. With respect to normal cardiac conduction, the electrical impulse that depolarizes the heart normally originates in the sinoatrial (SA) node (choice E). The depolarizing impulse travels from the SA node concentrically through the atrial myocardium (choice A), eventually reaching the atrioventricular (AV) node (choice B). From the AV node, the depolarizing impulse enters the His-bundles (choice C), where conduction becomes rapid again. The His-bundle penetrates the interarterial septum, where it divides into the right bundle branch (RBB) and left bundle branch (LBB). The RBB and LBB arborize into a fine network of Purkinje fibers (choice D). The Purkinje fibers penetrate the ventricular myocardium and function to depolarize the ventricular muscle mass, leading to ventricular contraction.

Front 504

Where in the autonomic nervous system is norepinephrine stored?A. Preganglionic sympathetic nerve endingsB. Postganglionic sympathetic nerve endingsC. Preganglionic parasympathetic nerve endingsD. Postganglionic parasympathetic nerve endings

Back 504

Postganglionic sympathetic nerve endingsThe correct answer is Choice B. Norepinephrine is synthesized and stored in vesicles located in the postganglionic sympathetic nerve endings (Choice B). Preganglionic sympathetic nerve endings (Choice A), preganglionic parasympathetic nerve endings (Choice C), and postganglionic parasympathetic nerve endings (Choice D) are all cholinergic because the neurosecretory transmitter for these neurons to acetylcholine.

Front 505

Where is norepinephrine stored?1. At preganglionic sympathetic nerve endings2. At postganglionic sympathetic nerve endings3. At preganglionic parasympathetic nerve endings4. At postganglionic parasympathetic nerve endings

Back 505

At postganglionic sympathetic nerve endingsThe correct answer is #2, at the postsynaptic ganglionic sympathetic nerve endings. Norepinephrine is the transmitter in C postganglionic neurons of the autonomic nervous system. In the central nervous system norepinephrine-containing neurons are prominent in the locus ceruleus, which projects diffusely to the cortex, cerebellum and spinal cord and is involved in alerting mechanisms. Sympathetic postganglionic fibers usually store norepinephrine as their neurotransmitter. However, there are always exceptions to a rule. Sympathetic postganglionic neurons to sweat glands and to some of those causing dilatation of blood vessels in skeletal muscles are often cholinergic neurons. Again, the correct answer is #2, at postganglionic sympathetic nerve endings.

Front 506

Which of following vitamins prevents the destruction of fatty acids and vitamin A?A. Vitamin B6B. Vitamin CC. Vitamin DD. Vitamin EE. Vitamin K

Back 506

Vitamin EThe correct answer is D. Vitamins are typically classified as being fat-soluble or water-soluble. The fat soluble vitamins are vitamins A, D, E and K. All of the "B" vitamins and vitamin C are classified as being water-soluble vitamins. Vitamin E is responsible for preventing the breakdown of vitamin A and fatty acids. Vitamin E is typically found in meats, milk and vegetables. When Vitamin E is deficient, anemia can develop. Vitamin B6 (choice A) acts as a coenzyme in amino acid and lipid metabolism. Vitamin C (choice B) acts as a coenzyme; it delivers hydrogen ions and acts as an antioxidant. It is essential for connective tissue formation. Vitamin D (choice C) is required for normal bone growth as well as facilitating both calcium and phosphorus absorption from the intestinal tract. Vitamin K (choice E) is essential for liver synthesis of prothrombin and other clotting factors.

Front 507

Which of the following age-related skeletal changes will occur first in an individual's life?A. Appearance of major vertebral curvesB. Appearance of secondary dentitionC. Decrease in the bones mineral contentD. Fusion of epiphyseal platesE. Remodeling of the bone

Back 507

Appearance of major vertebral curvesThe correct answer is A. A review of the human skeleton can reveal important information about an individual's age and/or sex. In sequential order of one's life-span the following age- related events will occur: The appearance of major vertebral curves occur begin at the age of two fetal months. The fetal spine is "bow" shaped and the adult spine is more "S" shaped. The appearance of secondary dentition (choice B) occurs when the primary teeth are lost and the permanent teeth take their place. The fusion of epiphyseal plates (choice D) typically occur near the beginning of adulthood. The mineral content of bone (choice C) typically decreases after the age of 65. The bone remodeling process (choice E) is one that occurs throughout a persons life at a relatively constant rate and is not related to age. In the bone remodeling process, the matrix of the bone is replaced while leaving the bone as a whole unchanged.

Front 508

Which of the following amino acids can most easily be converted to tyrosine in the human body?1. Glycine2. Arginine3. Methionine4. Tryptophan5. Phenylalanine

Back 508

PhenylalanineThe correct answer is choice 5, phenylalanine. In the category of aromatic amino acids are phenylalanine, tyrosine and tryptophan. In phenylalanine, the R group contains a benzene ring and in tyrosine, it contains a phenol group. Therefore, forming tyrosine from phenylalanine only requires hydroxylation of the benzene ring at carbon 3. So the correct answer to question is choice 5.

Front 509

Which of the following causes activation of the pyloric pump, relaxation of the pylorus, and contraction of the lower esophageal sphincter?A. GastrinB. SecretinC. PepsinogenD. AcetylcholineE. Cholecystokinin

Back 509

GastrinThe correct answer is Choice A. Gastrin (Choice A) causes activation of the pyloric pump along with relaxation of the pylorus, and contraction of esophageal sphincter. It is a hormone released by the antral mucosa of the stomach. Secretin (Choice B) is also a hormone of the digestive tract. It is formed by the epithelial cells of the duodendum and its primary function is to stimulate pancreatic secretion of sodium bicarbonate. Pepsinogen (Choice C) is an inactive proenzyme formed and secreted by the chief cells of the gastric mucosa. When it comes into contact with hydrochloric acid, it becomes active enzyme pepsin. Acetylcholine (Choice D) is a neurotransmitter synthesized in the cytoplasm of synaptic terminals. Cholecystokinin (Choice E) secreted by the duodenal and upper jejunal mucosa is chiefly responsible for the stimulation of gallbladder contraction.

Front 510

Which of the following causes some degree of temporary alkalosis?1. Hyperventilation2. High fluid intake3. Excessive smoking4. Severe muscular effort5. Ingestion of ammonium chloride

Back 510

HyperventilationThe correct choice is #1, hyperventilation. Alveolar ventilation is adequate for oxygenation when it matches the oxygen with its supply. Hypoventilation leads to a buildup of pC02 and a decrease in p02. The buildup of pC02 leads to an acidotic state in the blood, and since it is caused by a respiratory abnormality; that is, hypoventilation, it is referred to as respiratory acidosis. Likewise, hyperventilation leads to a decrease in pC02 and an increase in p02 for an alkaline blood pH. This is called respiratory alkalosis. Drugs which depress the respiratory center in the medulla, such as barbiturates, will cause an acidosis. Also, some drugs may induce a hyperventilatory state, thus may induce a respiratory alkalosis. So again, the correct choice to question #62 is #1, hyperventilation.

Front 511

Which of the following cells are responsible for producing antibodies against the bacteria found in a abscessed tooth?A. FibroblastsB. Mast cellsC. MacrophagesD. Mesenchymal cellsE. Plasma cells

Back 511

Plasma cellsThe correct answer is E. Plasma cells are derived from lymphocytes. These cells are responsible for producing antibodies, including the antibodies produced against the bacteria found in a abscessed tooth. When an antibody binds to an antigen, an antibody-antigen complex is formed. The specificity of the binding depends on the type of antibody employed to the site of the infection. There are five major classes of antibodies: IgG, IgM, IgE, IgA and IgD. Fibroblasts (choice A) are the most common cells in the connective tissue proper. These cells are responsible for the production and maintenance of connective tissue fibers. Mast cells (choice B) are mobile connective tissue cells commonly found near blood vessels. The cytoplasm of these cells contain histamine which stimulates local inflammation when an infection or injury to the area is present. Macrophages (choice C) are large cells that primarily function to engulf damaged cells or pathogens in the body. Mesenchymal cells (choice D) are the stem cells present in many connective tissues. These cells respond to a local infection or injury by dividing and producing "daughter" cells that eventually differentiate into macrophages, fibroblasts or other connective tissue cells.

Front 512

A deficiency of choline in the diet may cause abnormalities in metabolism of1. lipids.2. proteins.3. minerals.4. carbohydrates.5. nucleoproteins.

Back 512

Choline Choline is a structural component of phosphatidylcholine or lecithin, a phosphoglyceride. Phosphoglycerides are major components of cell membranes. The raw material for the synthesis of phosphatidylcholine is dietary choline. In the absence of choline, phosphatidylcholine cannot be produced and a major phospholipid component of wall membranes will be unavailable. So the correct answer to question is choice 1. Choline is not directly involved in the metabolism of the other choices: proteins, minerals, carbohydrates or nucleoproteins.

Front 513

A deficiency of rhodopsin is most likely caused by decreased dietary intake of1. glucose.2. adenine.3. vitamin A.4. tryptophan.5. riboflavin.

Back 513

vitamin A. Rhodopsin is a photosensitive molecule in rods. It is made up of opsin and 1-cis-retinal. The precursor of 11-cis-retinal is II-trans-retinol, or vitamin A. Vitamin A is an essential vitamin; that is, it cannot be synthesized in mammals. The all-trans-retinol is converted to 11-cis-retinal by retinol dehydrogenase, followed by an isomerization between the 11th and 12th carbon double bonds, from trans to cis configuration by retinal isomerase. If vitamin A is deficient in the human it will lead to night blindness and eventual degeneration of the rods. So the correct choice is #3, vitamin A.

Front 514

A deficiency of vitamin A in a developing tooth most likely affects the1. pulp.2. enamel.3. dentin.4. cementum.

Back 514

EnamelTo answer this question it is important to think back to the development of the tooth. In looking at our choices, pulp enamel, dentine and cementum, we see that dentine, cementum and pulp are classified as connective tissues, while enamel may be classified as a product of epithelial cells. The tooth, therefore, is from mesenchymal and ectodermal origin. The mesenchyme is derived from neural crest, and the epithelium, as I mentioned before, is derived from ectoderm. Vitamin A plays a key role in protein synthesis of epithelial cells. The exact role has not been elucidated. However, you can see here that you can answer this question by just looking at your choices. So again, the correct choice is #2. (*enamel hypoplasia)

Front 515

A derivative of vitamin K is the coenzyme for which of the following?A. Production of menadiolB. Esteilfication of retinolC. Hydrolysis of peptide bondsD. Cross-linking of fibrinogenE. Carboxylation of glutamate side chains

Back 515

Carboxylation of glutamate side chainsVitamin K is essential for the normal synthesis of prothrombrin and several other clotting factors in the liver. It acts as a coenzyme for the carboxylation of glutamate side chains (Choice E) into 6 - carboxyglutamate. Without this vitamin K-independent carboxylation reaction, the prothrombin formed does not bind ca2+ and may result in hemorrhage and death. Choice A through D are incorrect as vitamin K is not the coenzyme for any of the reactions listed.

Front 516

A disease that results in the destruction of a large number of cells and their nuclei would be expected to cause an increased blood level of which of the following?A. AmmoniaB. DNAC. KetonesD. MitochondriaE. Uric acid

Back 516

Uric Acid When a cell is broken down, the majority of the cells constituents, such as proteins and sugars, are catabolized into non-toxic waste products. However, when DNA and RNA are catabolized only the sugars and pyrimidines are able to be used for energy production. The purines (adenine and guanine) cannot be catabolized; instead they are deaminated and excreted as uric acid. Uric acid is a relatively non-toxic nitrogenous waste product that is non-soluble in blood. When large amounts of uric acid are produced, this waste product will begin to accumulate due to an inability of the kidneys to excrete this substance. Hyperuricemia is a clinical condition where the uric acid levels in the blood are greater than 7.5 mg/dL. This condition often develop into clinical state called gout. Since ammonia (choice A) is not found in the interior of a cell, blood levels of ammonia would not be expected to increase. DNA (choice B) blood levels would not increase in a disease that results in the destruction of a large number of cells and their nuclei because this compound is catabolized into waste products and uric acid. Ketones (choice C) are produced when lipids and amino acids are catabolized. Although mitochondria (choice D) pre found in the inside of a cell, they would also be catabolized when the cell is destroyed.

Front 517

A lack of exercise has which of the following physiological effects on bone?A. Bones are able to store more calciumB. Bones become thin and brittleC. Bones increase in lengthD. Exercise or lack thereof has no effect on boneE. The thickness-of the bone increases

Back 517

Bones become thin and brittle.Since bones are adaptable, their shapes often reflect the forces applied to them on a regular basis. For example, the various bumps and ridges on the surface of bone often indicate the sites where tendons attach to the bone. As the muscle becomes stronger and the force applied to the bone becomes larger, these bumps and ridges will become larger to withstand the increased force applied to them. Conversely, during periods of inactivity the size of the bone will decrease and the bone will subsequently become thin and brittle. In general, bones are able to store more calcium (choice A), increase in length (choice C), and the thickness of the bone will increase in periods of activity (choice E). Based on this information, it is easy to conclude that exercise or lack thereof does have an effect on bone (choice D).

Front 518

A man is being chased by a vicious dog. Secondary to stimulation of the sympathetic nervous system, which of the following would most likely occur?A. Decreased heart rateB. Dilation of the peripheral blood vesselsC. Dilation of the pupilsD. Increased peristalsis in the small intestineE. lncreased secretions of the salivary glands

Back 518

Dilation of the PupilsThe sympathetic nervous system promotes the "fight or flight" reaction. During periods of stress, the sympathetic nervous system will help the body handle the stressor by promoting a series of physiologic changes. For example, one would expect to see dilation of the pupils, secretion of the sweat glands, increased heart rate, constriction of the blood vessels to nonessential organs, bronchodilation, and decreased peristalsis. All the other answer choice decreased heart rate (choice A), dilation of the peripheral blood vessels (choice B), increased peristalsis in the small intestine (choice D), and increased secretions of the salivary glands (choice E) would be expected to occur with the stimulation of the parasympathetic nervous system.

Front 519

A muscle devoid of tonus is1. atonic.2. spastic.3. hypotonic.4. hypertonic.

Back 519

atonic. This is a simple definition-type problem. An atonic muscle will be flaccid. The muscle will be freely movable, and lies without tone. This occurs with lower motor neuron lesions; that is, the destruction of the alpha motor neurons. Spasticity is a hypertonus state of the affected muscles. This is due to a release of the tonic inhibition of the brainstem, facilitory information which leads to gamma motor neuron excitation. Thus, hyperactivity of the gamma fibers causes exaggerated response to stretch of muscle spindles. Hypotonia is simply a decrease in alpha motor neuron stimulation; however, not a complete destruction. So therefore we have partial tone loss. So again, the correct choice to question is #1, atonic.

Front 520

A patient diagnosed with cystinuria will have difficulties reabsorbing all of the following in the renal tubules EXCEPTA. arginineB. cysteineC. lysineD. methionineE. ornithine

Back 520

MethionineThe transport systems for amino acids in the intestinal and luminal cells are similar to those for glucose, where transport across the luminal membrane is sodium dependent and transport across the contraluminal membrane is sodium independent. Genetic deficiencies in a variety of these carrier systems have been identified. For example, cystinuria is a clinical condition arising from faulty transport mechanisms. It is an autosomal-recessive disease caused by a defect in the transport of cysteine, ornithine, arginine, and lysine, resulting in these amino acids being excreted in the urine. A mnemonic: cystinuria results from an inability to reabsorb COAL (cysteine, ornithine, arginine, and lysine) in the renal tubules.

Front 521

A patient presents with dry skin, cold intolerance, constipation, muscle weakness, recent weight gain, chronic lethargy, easy fatigue, loss of ambition, and periorbital puffiness. This patient's condition is most likely caused by which of the following?A. Aldosterone hypersecretionB. Androgen hypersecretionC. HypercortisolismD. HypocorticoidismE. Hypothyroidism

Back 521

HypothyroidismHypothyroidism, or myxedema, is caused by a lack of thyroid function. Patients with this condition often present with dry skin, cold intolerance, constipation, muscle weakness, recent weight gain, chronic lethargy, easy fatigue, loss of ambition, and periorbital puffiness. Aldosteronism is caused by a hypersecretion of aldosterone (choice A), leading to hypokalemia, which can eventually lead to periods of muscle paralysis. Adrenogenital syndrome is the result of excessive production of androgens (choice B), leading to premature masculinizing effects in young males. Cushing syndrome, which is caused by a hypersecretion of cortisol (choice C) by the adrenal cortex, is characterized by an increased fat deposition in the thoracic region and an edematous appearance of the face; it may also cause acne and hirsutism. Addison disease results from the failure of the adrenal cortex to produce adrenocortical hormones, resulting in glucocorticoid (choice D) and mineralocorticoid deficiency. Loss of cortisol (a glucocorticoid) secretion results in the depression of many metabolic functions and decreases one's ability to tolerate various stressors.

Front 522

A person who is severely deficient in folic acid would most likely experience which of the following?A. AcidosisB. AnemiaC. HemorrhageD. SeizureE. Thrombocytopenia

Back 522

AnemiaAnemia is a condition marked by a reduction in the hemoglobin and/or hematocrit content of the blood; this condition can be caused by a number of factors, one of which includes folic acid deficiency. Folic acid is the generic term for pteroylmonoglutamic acid, which serves as an important mediator of many reactions involving one-carbon transfers. This substance is found in many fruits and vegetables, especially citrus fruits and green leafy vegetables. The most common cause of folate deficiency is inadequate dietary intake and individuals most commonly seen with folate deficiency are alcoholics, the elderly and anorexic patients. The most common signs and symptoms of folic acid deficiency are megaloblastic anemia, with changes in the mucosa. The diagnosis is made upon finding macrocytic anemia with macroovalocytes and hypersegmented neutrophils on peripheral blood smear. Acidosis (choice A) is a condition where the blood pH is less than 7.4 and is not related to folic acid content in the body. Hemorrhage (choice C) can be caused by a number of factors, including vitamin K deficiency. Adequate amounts of vitamin K must be present for the liver to be able to synthesize four clotting factors, which include prothrombin. Without vitamin K, the entire clotting system will be inactivated. Therefore, if an individual were vitamin K deficient, they would most likely experience some degree of hemorrhage because the body would be unable to stop bleeding in a traumatic event. A seizure (choice D) can be defined as a condition characterized by a sudden onset of convulsions or other epileptic symptoms; its incidence is not increased in folic acid deficiency. Thrombocytopenia (choice E) is characterized by an abnormally low platelet count; its incidence is also not increased in folic acid deficiency.

Front 523

A protein in solution is at its isoelectric point when theA. pH is the same as that of the blood.B. logarithm of the concentration is zero.C. pH allows for maximum solubility.D. pH is such that no migration occurs during electrophoresis.E. pH is produced by a 1:1 mixture of the protein solution with isotonic saline.

Back 523

pH is such that no migration occurs during electrophoresis.The isoelectric point is the pH reached when there is no net electric charge on a protein. In other words, no migration of a protein in an electric field occurs during electrophoresis (Choice D) Choices A, B, C, and E do not describe isoelectric point

Front 524

A reduction in the population of which of the following lymphocytes would impair all aspects of an immune response?A. B cellsB. Cytotoxic T cellsC. Helper T cellsD. Memory T cellsE. Suppressor T cells

Back 524

Helper T cellsSpecific immunity is provided by the coordinated activities of both the T cells and B cells when antigens invade the human body. T cells play a crucial role in the initiation, maintenance and control of the immune response. Helper T cells stimulate the responses of both the T cells and B cells. They are absolutely essential to the immune response since B cells and other T cells must be activated by the helper T cells. Without helper T cells, an immune response to a given pathogen will not be elicited. The immunodeficiency caused by the AIDS virus occurs secondary to a reduction of helper T cells. B cells (choice A) are responsible for launching a chemical attack on antigens through the production of antibodies; without B cells an immu.ne response can still be elicited by T cells. Cytotoxic T cells (choice C) are responsible for cell mediated immiinity; these cells provide a direct physical and chemical attack on antigens. Memory T cells (choice D) remain long after an antigen enters the body. These cells ensure that an immediate immune response is elicited when the "same" antigen enters the body again. The suppressor T cells (choice E) inhibit both T cell and B cell activities; they moderate the immune response.

Front 525

Acidosis is most likely to occur in patients severely deficient in which of the following hormones?A. Antidiuretic hormoneB. CalcitoninC. InsulinD. ProlactinE. Thyroxine

Back 525

Insulin Ketoacidosis, a specific form of acidosis, is most commonly seen in diabetic patients deficient in insulin. When an individual is insulin deficient, the cells of the body are unable to properly utilize the glucose in the blood. Therefore, the body breaks down fatty acids in an effort to maintain normal physiological functions. When these fatty acids are broken down, large numbers of ketone bodies are formed and the blood pH decreases, leading to systemic acidosis. Antidiuretic hormone (choice A) prevents excessive water loss. In the absence of the hormone dehydration can occur. Calcitonin (choice B) is primarily responsible for the regulation of calcium ion concentrations in the blood. When blood levels calcium ions become elevated, calcitonin is secreted to reduce calcium ion levels to normal limit. Deficiencies of calcitonin would result in the development of hypercalcemia. Prolactin (choice D) is responsible for the production of milk in the mammary glands of women after pregnancy. If the hormone were deficient in a "new" mother, milk production would be substantially decreased. The thyroid hormones, such as thyroxine (choice E), are responsible for the elevation of oxygen consumption and the rate of energy consumption; increased heart rate; stimulation of activity of other endocrine tissue; maintenance of sensitivity of respiratory centers as well as various other functions. Individuals deficient in thyroid hormones are typically lethargic, unable to adjust to cold temperatures, have dry skin and some degree of hair loss, muscle weakness and slowed reflexes

Front 526

ADH receptors in the nephron are located on the tubular membrane of which of the following?A. Distal tubuleB. Proximal tubuleC. Ascending loop of HenleD. Descending loop of Henle

Back 526

Distal Tubule The nephron is the functional unit of the kidney. It is organized into different components each with specialized functions. ADH receptors are located on the distal tubule (Choice A) portion of the nephron. The distal tubule is responsible for the reabsorption if ions such as sodium, potassium, and chloride. Under the influence of ADH, the distal tubule can also dilute or concentrate the urine by regulating the amount of water entering into its lumen. Choice B, proximal tubule, functions mainly in the reabsorption of glucose. No ADH receptors are present in this segment of the nephron. Choice C, ascending loop of Henle, is virtually impermeable to water and it's also responsible for reabsorption of ions. Choice D the descending loop of Henle is highly permeable to water and functions mainly to allow simple diffusion of substances through its walls. Like the absorption part of the loop, it does not posess ADH receptors

Front 527

Which of the following characterize the links between monomeric units of nucleic acids?1. Ionic bonds2. Glycosidic bonds3. Phosphodiester bonds4. Phosphotriester bonds

Back 527

The correct answer is choice 3. Monomeric units of DNA consist of a phosphate group, deoxyribose, sugar, and nitrogen base of adenine, guanine, cytosine or thymine. These monomeric units are linked together to form the DNA strand by phosphodiester bonds. In these bonds, the 3-prime carbon of one deoxyribose links with one oxygen of the phosphate group, while a 5-prime carbon of another deoxyribose links with another oxygen of the phosphate group. This is known as a phosphodiester bond, indicating two bonds to a phosphate group. So the correct answer to question is choice 3.

Front 528

Albinism is a genetic disease that results in incomplete metabolism of1. alanine.2. tyrosine.3. cysteine.4. histidine.5. tryptophan.

Back 528

tyrosineAlbinism is a condition in which melanin is not produced and pigment is absent from skin, hair and the iris of the eyes. It is due to the absence of the enzyme tyrosinase. Tyrosinase is a copper-containing enzyme which acts on tyrosine to form dopaquinone which cyclizes and eventually forms melanin. Melanin granules are generally both dark and insoluble and are composed of high molecular weight polymers. Anyway, we need tyrosine for tyrosinase to act on to form melanin and the correct answer to question is choice 2.

Front 529

Aldosterone is normally associated with partial regulation of which of the following processes?1. Sodium balance2. Gluconeogenesis3. Lipid digestion4. Protein degradation5. Carbohydrate metabolism

Back 529

sodium balance. Aldosterone is a mineralocorticoid which is synthesized by the zona glomerulosa of the adrenal cortex. Aldosterone increases the resorption of sodium from gastric secretions, sweat, urine and saliva. Aldosterone acts on the epithelium of the distal tubule and collecting duct in the kidney. It does three important things: (1) it increases the resorption of sodium (2) promotes secretion of potassium and (3) promotes the secretion of hydrogen. Sodium retention occurs with excessive secretion of aldosterone. Along with increased sodium retention goes expansion of extracellular fluid volume, depletion of potassium and consequently metabolism alkalosis. Deficiency of aldosterone results in loss of sodium, hyperkalemia and acidosis. The renin angiotensin system regulates aldosterone. Angiotensin II stimulates secretion of aldosterone. Aldosterone secretion also increases with increasing plasma potassium concentrations and decreases with decreasing plasma potassium concentrations. Again, the correct choice is #1.

Front 530

`All of the following are associated with the action of postganglionic sympathetic fibers EXCEPTA. Constriction of pupilsB. Increased heart rateC. Increased sweat secretionD. Reduction of blood flow to the skinE. Release of stored lipids from subcutaneous adipose tissue

Back 530

Pupil ConstrictionThe major actions of the postganglionic sympathetic fibers are as follows: dilation of the pupils (NOT constriction of the pupils) and focusing on distant objects; acceleration of the heart rate (choice B) and increased force of contraction; increased sweat secretion from the sweat glands (choice C); constriction of cutaneous blood vessels leading to a reduction of blood flow to the skin (choice D); and release of stored lipids from subcutaneous adipose tissue (choice E).

Front 531

All of the following are derivatives of the amino acid tyrosine EXCEPTA. DopamineB. EpinephrineC. MelatoninD. NorepinephrineE. Thyroxine

Back 531

Melatonin Some hormones are small molecules that are structurally related to amino acids. For example, the following are derivatives of the amino acid tyrosine: dopamine (choice A), epinephrine (choice B), norepinephrine (choice D) and the thyroid hormones, thyroxine (choice E) and triiodothyronine. With respect to the synthesis of norepinephrine, the following steps apply. The synthesis of norepinephrine begins in the axoplasm of the terminal nerve endings of adrenergic fibers and is completed inside the vesicles of these fibers. The basic steps in the synthesis of norepinephrine are as follows: Tyrosine is converted to DOPA through the process of hydroxylation and then DOPA undergoes decarboxylation to become dopamine. Dopamine is then transported into the vesicles of the adrenergic fibers where it undergoes hydroxylation to become norepinephrine. In the adrenal medulla, norepinepherine is transformed into epinephrine through the process of methylation. Choline is combined with Acetyl-CoA to become acetylcholine. Melatonin (choice C) is a derivative of the amino acid tryptophan.

Front 532

All of the following are essential amino acids in adults EXCEPTA. arginineB. isoleucineC. leucineD. methionineE. tryptophan

Back 532

ArginineAn essential amino acid is one that cannot be synthesized in adequate amounts to meet the needs of the cell and therefore must be supplied by dietary protein. There are 10 essential amino acids: arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Two of these (arginine and histidine) are considered "essential" only in infants and children. A mnemonic to help remember these amino acids is as follows: "Any help in learning these little molecules proves valuable."OREssential Amino AcidsPriVaTe TIM HALLPhe, Val, Thr, Trp, Ile, Met, His, Arg, Leu, Lys

Front 533

Nitric oxide:What is the amino acid precursor?(Extra)

Back 533

ArginineWhen the dentist works on your teeth, you say, "AAArg! (Arginine)" before he administers Nitric Oxide (NO) to take the pain away.Other players necessary for NO synthesis: NO synthase, Ca++, NADPH.

Front 534

All of the following are the result of parasympathetic stimulation EXCEPTA. Contraction of the urinary bladder during urinationB. Constriction of the pupilsC. Increased heart rateD. Increased salivary gland secretionE. Increased smooth muscle activity of the intestinal tract

Back 534

Increased HRThe parasympathetic and sympathetic nervous systems, for the most part, oppose each other. The major actions of the parasympathetic nervous system are as follows: Decreased heart rate (NOT increased heart rate); Contraction of the urinary bladder during urination (choice A), constriction of the pupils (choice B) increased salivary gland secretion (choice D) and increased smooth muscle activity of the intestinal tract (choice E). Other parasympathetic actions include secretion of hormones that promote the absorption and utilization of nutrients by peripheral cells, stimulation and coordination of defecation, constriction of the respiratory pathways and sexual arousal and stimulation of sexual glands in both sexes.

Front 535

All of the following changes in the skeleton are considered age-related EXCEPTA. Appearance of major vertebral curvesB. Appearance of secondary dentitionC. Decrease in mineral content of the bonesD. Fusion of epiphyseal platesE. Remodeling of the bone

Back 535

Remodeling of boneA review of the human skeleton can reveal important information about an individual's age and/or sex. However, there are certain characteristics of the human skeleton that are independent of an individuals age or sex. For example, bone remodeling is a process that occurs throughout a persons life at a relatively constant rate. In the "remodeling" process, the matrix of the bone is replaced while leaving the bone as whole unchanged. With respect to individual variations in the skeletal system, the following principles apply: The appearance of major vertebral curves occur between the age of 2 fetal months and adulthood (choice A); The fetal spine is "bow" shaped and the adult spine is more "S" shaped. The appearance of secondary dentition (choice B) , occurs when the primary teeth are lost and the permanent teeth take their place. The mineral content of bone (choice C) typically decreases after the age of 65. The fusion of epiphyseal plates (choice D) typically occurs near the beginning of adulthood.

Front 536

All of the following hormones involved in the regulation of bone growth stimulate osteoblast activity and the synthesis of bone matrix EXCEPTA. EstrogenB. Growth hormoneC. Parathyroid hormoneD. TestosteroneE. Thyroxine

Back 536

Parathyroid Hormone Normal bone growth and maintenance depend on a combination of hormonal and nutritional factors. With respect to the hormonal factors, the only hormone involved in the regulation of bone growth, listed as an answer choice, that does not stimulate osteoblast activity and the synthesis of bone matrix is parathyroid hormone. Parathyroid hormone is responsible for stimulation of osteoclast activity and elevation of calcium ion concentrations in body fluids. Estrogen (choice A) secreted in the ovaries, Growth hormone (choice B) secreted from the pituitary gland, Testosterone (choice D) secreted from the testes, and Thyroxine (choice E) secreted from the follicle cells of the thyroid gland, are all responsible for stimulating osteoblast activity and synthesis of bone matrix to either a small or large degree.

Front 537

All of the following hormones promote protein synthesis EXCEPTA. CortisoneB. EstrogenC. InsulinD. Growth hormoneE. Testosterone

Back 537

Cortisone A summary of protein synthesis is as follows: An mRNA strand contains codons that are complementary to the DNA strand. The molecules of tRNA contain the anticodons that are complementary to the mRNA codons. Different amino acids are then delivered by the tRNA's. The sequence of amino acids in the completed peptide will reflect the sequence of the tRNA arrivals. The human body then uses these amino acids to build proteins. Cortisone is a glucocorticoid hormone that has the following effects on the peripheral tissues: It decreases the use of glucose and releases amino acids from skeletal muscles and lipids from adipose tissue. Cortisone also has anti-inflammatory effects. Estrogens (choice B) and androgens, such as testosterone, (choice E) are "sex hormones" that increase the rate of amino acid usage in protein synthesis. Insulin (choice C) is primarily responsible for increasing glucose uptake and utilization in the liver, adipose tissue and skeletal muscle. Insulin also promotes increased amino acid uptake and protein synthesis. This is also one of the primary functions of growth hormone (choice D).

Front 538

All of the following statements are true with respect to blood pressure and resistance to blood flow EXCEPTA. blood pressure increases with a decrease in arterial elasticityB. resistance to blood flow is directly related to the blood viscosityC. resistance to blood flow is directly related to vessel diameterD. stroke volume is directly related to blood pressureE. vascular resistance is directly proportional to the length of the blood vessel

Back 538

resistance to blood flow is directly related to vessel diameterWith respect to the vascular system, resistance represents the opposition to the flow of blood. A number of factors can affect blood flow, such as vessel diameter, arterial elasticity, blood viscosity, and vessel length. As the vessel diameter increases, resistance to blood flow will decrease. In other words, resistance to blood flow is inversely, not directly, related to vessel diameter.

Front 539

All of the following statements are true with respect to deglutition EXCEPTA. approximately one-twelfth of all "swallows" that occur daily occur during sleepB. food is moved to the esophagus under the direction of cranial nerve XIIC. involuntary contraction of the pharynx advances the bolus into the esophagusD. the nucleus of the solitary tract coordinates the swallowing mechanismE. swallowing is triggered by cranial nerves VIII and IX

Back 539

swallowing is triggered by cranial nerves VIII and IX (is incorrect)Swallowing is a reflex action with its afferent impulses carried primarily by the glossopharyngeal (CN IX) and vagus (CN X) nerves. The act of swallowing is triggered by cranial nerves IX and X, not VIII and IX. All the other statements about deglutition are true. Approximately one twelfth of all daily "swallows" occur during sleep (choice A), and one-third occur during eating. Food is moved to the esophagus under the direction of cranial nerve XII (choice B). Involuntary contraction of the pharynx advances the bolus into the esophagus (choice C). The nucleus of the solitary tract coordinates the swallowing mechanism (choice D) via the nucleus ambigus and hypoglossal nucleus.

Front 540

All of the following statements are true with respect to proteins EXCEPT:A. Proteins are the structural components of androgensB. Proteins are the structural components of antibodiesC. Proteins consist of small organic molecules called amino acidsD. Proteins help to create the threedimensional framework of the bodyE. Protein structures transport materials around the body

Back 540

Proteins are the structural components of androgens Proteins perform a variety of essential functions in the body; these functions include the following: The proteins of the immune system are known as antibodies. In other words, proteins are the structural components of antibodies (choice B). Proteins consist of small organic molecules called amino acids (choice C). The human body contains significant quantities of about 20 different amino acids. In fact, these proteins help to create the three-dimensional framework of the body (choice D). Insoluble lipids, respiratory gasses, special minerals, such as iron and several hormones are carried throughout the body attached to special transport proteins (choice E). Cholesterol is the structural component of androgens (choice A).

Front 541

All of the following would lead to an increase in the glomerular filtration rate EXCEPTA. Constricting the efferent arteriolesB. Decreasing plasma protein concentrationsC. Decreasing renin levelsD. Dilation of the afferent arterioleE. Inhibition of sympathetic stimulation of the kidney

Back 541

Decreasing renin levelsThe glomerular filtration rate is defined as the amount of filtrate produced in the kidneys each minute, which averages around 125 mL of filtrate per minute. There are many different factors that can alter (increase or decrease) the glomerular filtration rate. For example, when renin levels are decreased (choice C), there is a decreased conversion of angiotensin I to angiotensin II. Since angiotensin II is a potent constrictor of the efferent arteriole, decreasing renin will decrease the GFR. Constricting the efferent arterioles choice A) and dilation of the afferent arteriole (choice D) will directly increase the glomerular filtration rate. Conversely, constriction of the afferent arteriole often occurs when there is a fall in blood pressure, which will lead to a decrease in the glomerular filtration rate. The constriction of the afferent arteriole occurs when there is sympathetic stimulation of the kidney; therefore, inhibition of sympathetic stimulation of the kidney (choice E) will cause glomerular filtration rate to increase. When plasma protein concentrations are decreased (choice B), the kidneys will increase the glomerular filtration rate to increase the production of urine.

Front 542

An alcoholic man is diagnosed with Wernicke triad and Korsakoff syndrome. Which of the following would be the most appropriate treatment for this patient?A. BiotinB. NiacinC. PyridoxineD. RiboflavinE. Thiamine

Back 542

ThiamineThe diagnosis of classic Wernicke triad (ophthalmoplegia, ataxia, and global confusion) and Korsakoff psychosis is considered to be a medical emergency that necessitates the immediate administration of thiamine, or vitamin B1. Biotin (choice A) acts as a carrier of "activated carboxyl" groups for three key enzymes that catalyze carboxylation reactions. Symptoms of biotin deficiency are alopecia, skin and bowel inflammation, and muscle pain. Niacin (choice B), or vitamin B3, is converted to nicotinamide, which is then incorporated into the coenzymes NAD+ and NADP+. Pellagra is a condition associated with a deficiency of niacin, which can result in the development of diarrhea, dermatitis, and dementia. Pyridoxine (choice C), or vitamin B6, is associated with the coenzyme pyridoxal phosphate. A deficiency in pyridoxine can lead to the development of peripheral neuropathy and dermatitis. Riboflavin (choice D), or vitamin BP, is responsible for maintaining proper levels of both flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Individuals deficient in riboflavin are likely to present with lesions of the lips, mouth, skin, and genitalia.

Front 543

An electrocardiogram showing extra P waves before each QRS complex indicates1. fibrillation.2. atrial bradycardia.3. partial heart block.4. ventricular tachycardia.5. left bundle branch block.

Back 543

Partial Heart BLock In order to understand this question you must be familiar with the normal ECG tracings. The P-wave is the first wave of the ECG tracing, and it represents the spread of depolarization through the atria. The P-R interval is measured from the beginning of the P-wave to the beginning of the QRS complex. It reflects the time it takes for the depolarization impulse to travel from the S-A node to the ventricular myocardium. The P-R segment is measured between the end of the P-wave and the beginning of the QRS complex. It reflects the spread of depolarization through the A-V node, the bundle of His and the Purkinje fibers. The QRS complex is the second and most important deflection on the ECG tracing. It represents the spread of depolarization through the ventricular muscle. The ST segment is measured from the end of the QRS to the beginning of the T wave. It represents the portion of the cardiac cycle in which all the ventricular myocardial fibers are depolarized and no further current flows. The T-wave is the third deflection of the QRS and represents the recovery period or repolarization of the ventricles. The Q-T interval is measured from the beginning of the QRS to the end of the T-wave and gives the total duration of ventricular systole. Partial heart block represents a delay in the transmission of the action potential from the atrial pacemaker to the ventricles. This delay may be due to abnormalities in the atria or the A-V node or the bundle of His, and is reflected by prolongation of the P-R interval on the ECG. It is also characterized by extra P-waves before each QRS complex. So again, the correct choice to question is #3, partial heart block.

Front 544

An impulse can travel from one nerve to another in only one direction because the1. synapse limits the direction of travel.2. myelin sheath limits the direction of travel.3. myoneural junction limits the direction of travel.4. nerve fiber permits conduction in only one direction.5. cell body must be stimulated before the nerve fiber will conduct.

Back 544

synapse limits the direction of travelAction potentials are propagated along the axon. The electrical conduction between neurons occurs by gap junctions. Chemical transmission occurs at the synapse. The neurotransmitter, upon arrival of the impulse, is released by the presynaptic neuron and reacts with receptors on the postsynaptic neuron. The conductance for ions is then increased, and an electrochemical current is propagated. Since the presynaptic neuron releases the neurotransmitter upon arrival of the impulse the impulse is unidirectional. Gue to the synapse the myelin sheath limits the direction of lateral conduction to adjacent nerves. Conduction along the nerve fiber itself can be bidirectional, and the nerve conducts an impulse due to the amval of the action potential. So again, the correct choice is #1, synapse limits the direction of travel.

Front 545

An individual deficient in which of the following is most likely to develop pernicious anemia?A. CholecystokinB. GastrinC. Hydrochloric acidD. Intrinsic factorE. Secretin

Back 545

Intrinsic FactorIntrinsic factor is the secretion of parietal cells that facilitates the absorption of vitamin B12 across the intestinal lining. Vitamin B12 is a member of the cobalamin family and serves as a cofactor for two important reactions in humans. As methylcobalamin, it serves as a cofactor for methionine synthetase in the Conversion of homocysteine to methionine, and as idenosylcobalamin, it serves as a cofactor for the snversion of methyl-malonyl-CoA to succinyl-CoA after being ingested, it becomes bound to intrinsic factor, which is a protein secreted by gastric parietal cells. Once absorbed, it is stored in the liver. The most common disorder seen with Vitamin B12 deficiency is pernicious anemia, which is associated with the development of a megaloblastic anemia. This megaloblastic state often leads to various mucosal changes, intestinal disturbances, such as anorexia and diarrhea, and a neurological syndrome where the peripheral nerves are often affected first, causing paresthesias and difficulty i n balance. Cholecystokinin (choice A) is produced and stored in the I cells of the duodenal and jejunal mucosa. The parietal cell secretes two substances: intrinsic factor and hydrochloric acid. The hormone gastrin (choice B), which is produced in the G cells of the duodenum, primarily functions to stimulate hydrochloric acid, histamine, and pepsinogen secretion as well as increase gastric blood flow. Hydrochloric acid (choice C) functions primarily to denature proteins and activate digestive enzymes. Secretin (choice E) is synthesized and stored in the S cells of the upper intestine. It stimulates the secretion of bicarbonate containing substances from the pancreas and inhibits gastric emptying and gastric acid production.

Front 546

An individual that has anti-A agglutinins and Rh agglutinogens would have which of the following classifications of blood?A. Type A negativeB. Type A positiveC. Type B negativeD. Type B positiveE. Type AB positive

Back 546

Type B +There are two antigens (type A and type E) that appear on the surfaces of red blood cells. Furthermore, strong antibodies that react specifically with either the type A or type B antigens, occur in individuals who do not have these particular antigens on their cells. Hence, type A and type B antigens are called agglutinogens and the antibodies that cause agglutination are called anti A/B agglutinins. Along the same lines, individuals who have the Rh agglutinogen will be Rh+, and those without the Rh agglutinogen will produce the anti-Rh agglutinin. Remember that agglutinogens are antigens, and agglutinins are antibodies. An individual that has anti-A agglutinins and Rh agglutinogens would have a Type B (+) blood classification. One would expect to see antiB agglutinin and no Rh agglutinogen in a person with type A (-) blood (choice A), conversely anti-B agglutinin and Rh agglutinogen (choice B) is seen in persons with A (+) blood. Anti-A agglutinin and no Rh agglutinogen (choice C) is seen in B (-) blood types. When there are no anti-A or anti-B agglutinins (the person has both agglutinogens) and there is Rh agglutinogen, the person has blood type of AB positive (choice E).

Front 547

An individual who is chronically lethargic, unable to adjust to cold temperatures and has chronic dry skin is most likely deficient in of which of the following hormones?A. CalcitoninB. Growth hormoneC. Parathyroid hormoneD. TestosteroneE. Thyroid hormone

Back 547

Thyroid HormoneAdults with hypothyroidism are chronically lethargic, unable to adjust to cold temperatures and often have chronically dry skin as well as have some degree of hair loss, muscle weakness and slowed reflexes. In other words, the patient in this question is most likely deficient in their thyroid hormones, since the effects of thyroid hormones are as follows: Elevation of oxygen consumption and the rate of energy consumption; increased heart rate; stimulation of activity of other endocrine tissues; maintenance of sensitivity of respiratory centers as well as various other functions. Calcitonin (choice A) is the hormone primarily responsible for the regulation of calcium ion concentrations in the blood. When blood levels of calcium ions become elevated, calcitonin is secreted to reduce calcium ion levels to normal limits; Therefore, deficiencies of calcitonin would result in the development of hypercalcemia. Growth hormone (choice B) stimulates cell growth and replication by accelerating the rate of protein synthesis. Individuals deficient in growth hormone are often described as "pituitary dwarfs". Parathyroid hormone (choice C) is responsible for increasing calcium ion concentrations in the body fluids; therefore individuals deficient in this hormone would most likely be hypocalcemic. Testosterone (choice D) promotes the production of functional sperm, maintains the secretory glands of the male reproductive tract and stimulates growth. Deficiencies of testosterone are associated with a decreased development of male secondary sex characteristics.

Front 548

An inflammatory response is triggered when which of the following occur?A. Blood flow to an area increasesB. Clot formation occursC. Fibroblasts secrete beta-interferonD. Mast cells release histamineE. Neutrophils phagocytize bacteria

Back 548

Mast cells release histamine Inflammation is a localized tissue response to injury that produces various local sensations, such as swelling, heat, redness and pain. There are many different factors that can cause inflammation, including abrasion, impact, irritation, and infection. Mast cells play an important role in the inflammation process. These cells release histamine, prostaglandins, heparin and other chemicals into the immediate area. When histamine is released, capillary permeability is increased and blood flow to the area increases. Although blood flow to the area (choice A) is the most common cause of inflammation, the inflammatory response is triggered when mast cells release histamine. Clot formation (choice B) is one of the final states of tissue repair; it does not promote inflammation. When fibroblasts secrete beta-interferon, this substance slows the inflammation process in damaged tissue. When neutrophils phagocytize bacteria (choice E), inflammation is not promoted.

Front 549

Antidiuretic hormone acts to1. decrease renal filtration fraction.2. increase storage capacity of the bladder.3. decrease permeability of distoconvoluted tubules and/or collecting ducts to water.4. increase permeability of distoconvoluted tubules and/or collecting ducts to water.

Back 549

increase permeability of distal convoluted tubules and/or collecting ducts to water. When plasma osmotic pressure changes the brain's osmoreceptors respond by stimulating or inhibiting antidiuretic hormone, abbreviated ADH. Axons of neurons in the supraoptic and paraventricular nuclei of the anterior hypothalamus extend down the pituitary stalk to the posterior lobe of the pituitary, where the axon terminals release secretory products into the blood. Vasopressin, or ADH, is one of the two hormones released. The other is oxytocin. ADH binds to specific cell receptors of the distal convoluted tubule and the collecting duct, activating adenylate cyclase; CAMP is produced, followed by activation of protein kinase. Water then flows across the cell, due to the phosphorylation of lumenal membrane components. Urine flow will decrease, and the osmolarity of bloodwill drop. In the presence of ADH the kidney will produce a small amount of very concentrated urine. Again, the correct choice is #4, increase permeability of the distal convoluted tubules and/or collecting ducts to water.

Front 550

Which of the following enzymes converts trypsinogen to trypsin?A. EnterokinaseB. PeptidaseC. SecretinD. Pepsin

Back 550

The correct answer is Choice A. Trypsin is a powerful proteolytic enzyme present in pancreatic secretions. It aids in the digestion of proteins. When synthesized in the pancreatic cells, the proteolytic enzyme is in its inactive form trypsinogen. It is important for the enzyme to remain inactive as it will digest the pancreas itself. Trypsinogen is activated to trypsin only after it is released into the intestinal tract by enterokinase (Choice A). Enterokinase is secreted by the intestinal mucosa when chyme comes into contact with the mucosa. Peptidase (Choice B) is an enzyme present in the microvilli of the small intestine capable of splitting large polypeptides into their components. Secretin (Choice C) is a hormone secreted by duodenal and jejunal mucosa in response to high acid content in the small intestine. This hormone in turn stimulates pancreatic secretion of sodium bicarbonate. Pepsin (Choice D) is the major digestive enzyme of the gastric juices. It is active in an acidic environment to digest proteins and collagen.

Front 551

Which of the following enzymes is involved in the synthesis of fatty acids? A. Acetyl CoA carboxylaseB. Glucose 6-phosphate dehydogenaseC. Glycogen synthaseD. PhosphorylaseE. Thiolase

Back 551

The correct answer is A. The synthesis of lipids is known as lipogenesis. Pathways of lipid synthesis begin with acetyl-CoA; these molecules can be stmng together in the cytosol yielding fatty acids. Acetyl CoA carboxylase is the key enzyme involved in fatty acid synthesis. Glucose 6- phosphate dehydogenase (choice B) is involved in the pentose phosphate pathway. The two enzymes involved in the synthesis and degradation of glycogen are phosphorylase and glycogen synthase. Furthermore, glycogen synthesis and degradation are coordinated by a hormone-triggered cascade, which ensures that when one enzyme is active, the other enzyme is inactive. The enzyme involved in glycogen degradation is phosphorylase (choice D) and the enzyme involved in glycogen synthesis is glycogen synthase (choice C), as the name implies. Thiolase (choice E) is responsible for converting acetoacetyl CoA into acetyl CoA

Front 552

Which of the following functions as part of the extracellular matrix? A. MucinB. HeparinC. CollagenaseD. Chondroitin sulfateE. Dolichol phosphate

Back 552

The correct answer is Choice D. Of the following, only chondroitin sulfate (Choice D) functions as part of the extracellular matrix. It is a proteoglycan that acts as a filler between collagen fibers and cells. Chondroitin sulfate is also a principal component in the organic matrix of bone and cartilage. Mucin (Choice A) is a mucus secretion produced by salivary glands that acts as a lubricant for surface protection. Heparin (Choice B) is a powerful anticoagulant produced mainly by the basophilic mast cells located in the pericapillary connective tissues. Collagenase (Choice C) is an enzyme that catalyzes the hydrolysis of collagen. It is not a functional part of normal extracellular matrix. Dolichol phosphate (Choice E) is a very long chain lipid that acts as a carrier for oligosaccharide.

Front 553

Which of the following groups includes only amino acids essential for humans? A. Valine, serine, leucineB. Leucine, lysine, glycineC. Tyrosine, threonine, tryptophanD. Phenylalanine, methionine, prolineE. Tryptophan, methionine, isoleucine

Back 553

The correct answer is Choice E. Amino acids are the basic building blocks of proteins. They are classified into two separate groups, the essential and the nonessential amino acids. The nonessential group includes amino acids that the body can synthesize. The essential amino acid group include ones that the body either cannot synthesize or are synthesized in amounts too small to meet the needs of the body. These amino acids must be supplied in the diet. The following is a list of essential amino acids: 1. Threonine 2. Lysine 3. Methionine 4. Arginine 5. Valine 6. Phenylalanine 7. Leucine 8. Tryptophan 9. Isoleucine 10. Histidine Of the choices listed, Choice E (tryptophan, methionine, isoleucine) contains only essential amino acids.

Front 554

Which of the following hormones are produced by the neurohypophysis and affect contraction of smooth muscle? 1. Vasopressin (ADH) and oxytocin2. Thyrotropin and intermedin3. Adrenotropin and somatotropin4. Aldosterone and luteinizing hormone

Back 554

The correct answer is choice 1. The neurohypophysis is another term for the posterior pituitary. The two major hormones produced by the posterior pituitary are ADH, also known as vasopressin, and oxytocin. ADH raises blood pressure and helps retain fluid by increasing permeability of collecting tubules in the kidney. Oxytocin causes uterine contraction and milk secretion. In choice 2, thyrotropin or TSH comes from the anterior pituitary and stimulates the thyroid gland; while intermedin or melanotropin is an anterior pituitary hormone that stimulates melanin production. And choice 3, adrenotropin or ACTH is another anterior pituitary hormone that stimulates the adrenal cortex, while somatotropin or growth hormone is another anterior pituitary hormone that stimulates overall body growth. And choice 4, aldosterone is an adrenal cortical hormone primarily responsible for sodium retention, while luteinizing hormone is an anterior pituitary hormone involved in triggering ovulation and formation of the corpus luteum. So the correct answer to question is choice 1.

Front 555

Avidin influences which of the following vitamins?1. Niacin2. Biotin3. Thiamine4. Tocopherol5. Phylloquinone

Back 555

BiotinThe correct answer is choice 2. Avidin, which is a glycoprotein found in egg white, can produce biotin deficiency as it binds biotin tightly, preventing its absorption from the intestine. It has no effect on any of the other choices. Choice 1, niacin, is involved in producing NAD and NADP and niacin deficiency leads to pellagra. Choice 3, thiamin, or vitamin B1 deficiency, causes beriberi. Thiamin acts as a co-enzyme in reactions involving aldehyde groups. Tocopherol, or vitamin E deficiency, is related to infertility, and vitamin E has antioxidant properties. Choice 5, phylloquinone, is a member of the quinone family. Quinones are involved in electron transport in the respiratory chain. So the correct answer to question is choice 2.(A,D,E,K are the fat soluble vitamins)(9 water soluble vitamins...8 B vitamins & Vit C)Fat Soluble Vitamins are Stored in the liver while water soluble are not stored and get eliminated in urine leading to the need of a continous supply in our diet)

Front 556

Bacteria in the intestinal tract are responsible for synthesis of all the following EXCEPTA. ammoniaB. ascorbic acidC. folic acidD. small organic acidsE. vitamin K

Back 556

Ascorbic Acid (Vitamin C)In normal feces, 30% of the solid waste may be composed of bacteria. In the intestinal tract, bacteria split urea to form ammonia (choice A) and synthesize folic acid (choice C), small organic acids (choice D) from unabsorbed fat and carbohydrates, and vitamin K. The brown color of feces is mainly due to the action of bacteria on bile pigments. The odor of feces is due to sulfides and indolic compounds. Ascorbic acid (choice B), or vitamin C, is NOT produced by the bacteria in the intestinal tract.

Front 557

Both control and regulation of sympathetic function primarily occur in centers in theA. cerebellumB. cerebrumC. mesencephalonD. posterior and lateral hypothalamusE. spinal cord and adrenal medulla

Back 557

E. spinal cord and adrenal medullaThe autonomic nervous system consists of two subdivisions, the sympathetic and parasympathet nervous systems. In summary, an increase sympathetic activity leads to stimulation of tissue metabolism, increased alertness and preparation of the body for an emergency. The sympathetic division consists of preganglionic neurons located between spinal segments TI and L2. Furthermore, the ganglionic neurons are also located in ganglia near the vertebral column. The center of each adrenal gland (adrenal medulla) is a modified sympathetic ganglion. In other words, both control and regulation of sympathetic function primarily occurs in centers in the spinal cord and adrenal medulla. The cerebellum (choice A) adjusts voluntary and involuntary motion activities as well as compares incoming sensory information with anticipated sensations. Consciousness, thought processes, sensations, intellectual function, memory storage and retrieval and complex motion actions originate in the cerebrum (choice B). The mesencephalon (choice C) is the center responsible for processing visual and auditory information. The posterior and lateral portion of the hypothalamus choice D) contain various centers involved with emotions, autonomic function and hormone production. Furthermore, the hypothalamus is the primary link between nervous and endocrine system.

Front 558

Breathing a gas mixture with 5 percent CO2, ultimately leads to which of the following?A. HypoventilationB. A decrease in heart rateC. A stimulation of central chemoreceptorsD. An inhibition of peripheral chemoreceptorsE. A decrease in cerebrospinal fluid hydrogen-ion concentration

Back 558

A stimulation of central chemoreceptorsC02 has a direct effect on the respiratory center of the brain in controlling respiration. Breathing a gas mixture with excess C02 will stimulate control chemoreceptors (Choice C) to cause increased strength of pulmonary ventilation, thus reducing C02 concentration by expiring greater amounts of C02 out of the body. Choice A is incorrect as an excess amount of C02 will ultimately lead to hyperventilation as the lungs labor to rid the body of CO2. Choice B is also incorrect as C02 concentration in the blood can stimulate peripheral chemoreceptors especially at the onset of exercise. It will not, however, inhibit peripheral chemoreceptors as stated in this choice. Choice E is incorrect as excess C02 can pass through the blood-cerebrospinal fluid barrier, react with water present to form hydrogen ions thus increasing the hydrogen ion concentration in the cerebrospinal fluid.

Front 559

Calcium ions initiate contraction in skeletal muscle when theyA. bind to T tubules.B. bind to troponin.C. interact with actin.D. interact with myosin.E. bind to sarcoplasmic reticulum.

Back 559

Bind to troponin. Calcium ions bind strongly to troponin (Choice B) changing the condition between troponintropomyosin complex and actin in the relaxed muscle state to produce a new relationship that leads to muscle contraction. T-tubule (Choice A) facilitates transmission of action potentials to all skeletal muscle fibers. It does not bind with calcium ions. Calcium ions also do not bind with actin (choice C) or myosin (Choice D). Actin must attach to the heads of the myosin filaments to cause contraction. Sarcoplasmic reticulum (Choice E) releases calcium ion in the vicinity of all myofibrils to bring about contraction.

Front 560

Calcium ions trigger contraction of muscles by binding to1. actin.2. myosin.3. troponin.4. tropomyosin.

Back 560

troponin During muscular contractions, the heavy meromyosin subunit of myosin extends to reach and bind with the actin filament. This binding activates the ATPase activity of the myosin head and in the presence of ATP, a confirmational change may occur in the end causing a spring like shortening. This results in pulling the actin filament past the myosin filament. Tropomyosin on the actin molecule covers the binding site for myosin cross bridges in the absence of calcium ion. When calclum ion is present, it binds to troponin and exposes the binding site on the actin molecule for myosin to interact and allows the contraction cycle to occur. Choice 1 is incorrect. Actin is a major protein found in the thin filament of the myofibril. Choice 2 is incorrect. Myosin is large protein consisting of two sets of light chains and one set of heavy chain composing the thick filament. Choice 4 is incorrect. Tropomyosin is found in the thin filament. These rod shaped molecules are associated with actins to form the basic structural component of the thin filament. So the correct answer to question is choice 3.

Front 561

Carbohydrate is stored in the body principally as1. glucose.2. maltose.3. sucrose.4. glycogen.5. glycosaminoglycans.

Back 561

glycogen. Glycogen is stored in the liver. At times, when glucose is in demand glycogen will be converted into glucose via glycogenolysis, which is the lysis of glycogen, or stored carbohydrate. Epinephrine, or glucagon, stimulates the conversion of ATP to cyclic AMP via adenylate cyclase. Cyclic AMP then converts protein kinase inactive to protein kinase active. Protein kinase aids in the phosphorylation of phosphorylase kinase inactive to phosphorylase kinase active via ATP. The phosphorylase kinase active then converts to phosphorylase-B inactive to phosphorylase-A active. This then releases successive glucose-1-phosphate residues from the branch chains of glycogen. Thus, we have the production of glucose from our stored carbohydrate. So again, the correct choice is 4, glycogen.

Front 562

Carbon monoxide decreases the amount of1. bicarbonate in the blood plasma.2. carbonic anhydrase available in the lungs.3. oxygen that can be transported by hemoglobin.4. alveolar surface available for gaseous exchange.5. carbon dioxide that can be transported by the blood.

Back 562

oxygen that can be transported by hemoglobin. Carbon monoxide combines with ferromyoglobin and ferrohemoglobin, interfering with oxygen transport. Heme has a high affinity for carbon monoxide. Myoglobin and hemoglobin have less affinity than the isolated heme. However, they still bind. These proteins decrease the affinity of carbon monoxide to the heme-protein complex by sterically hindering the binding of carbon monoxide. More specifically, the myoglobin and hemoglobin change the geometry of the binding of carbon monoxide from that of the protein-oxygen binding and in doing so weakens the interaction of carbon monoxide with the heme, optimizing O2 binding. Nevertheless, carbon monoxide has a greater affinity for binding than oxygen, and this fact decreases the amount of oxygen that can be transported by hemoglobin. So again, the correct choice is #3, oxygen that can be transported by hemoglobin.

Front 563

Cardiac muscle differs from the other types of muscle tissue in that cardiac muscleA. Contains visible striationsB. Forms muscle fibersC. Has both actin and myosin filamentsD. Has only one nucleus per cellE. Is able to contract without neural stimulation

Back 563

Is able to contract without neural stimulationThere are three types of muscle tissue in the human body: cardiac, skeletal and smooth muscle. All of these types of muscle tissue are specialized for contraction. Each of these types of muscle is designed to perform specific functions in the body. For example, cardiac muscle is found only in the heart and functions to circulate blood and maintain blood pressure. This type of muscle differs from skeletal and smooth muscle in that it is able to contract without neural stimulation. Within the cardiac muscle are specialized muscle cells called pacemaker cells, which establish a regular rate of contraction. Although the nervous system may alter the rate of pacemaker activity, it does not provide "control" over the cardiac muscle cells. Visible striations (choice A) are found in both skeletal and cardiac muscle. Both cardiac and skeletal muscle form muscle fibers (choice B). Actin and myosin filaments (choice C) are found in all three types of muscle. Although cardiac and smooth muscle contain one nucleus (choice D), skeletal muscle cells may contain hundreds of nuclei per cell.

Front 564

Cell bodies of sympathetic preganglionic neurons are located in1. dorsal root ganglia.2. sympathetic chain ganglia.3. the brain stem and the spinal cord.4. thoracic and lumbar segments of the spinal cord.5. none of the above.

Back 564

thoracic and lumbar segments of the spinal cord.Let's review the location of the cell bodies of pre- and post-ganglionic neurons of the sympathetic and parasympathetic nervous systems. In the sympathetic nervous system, pre-ganglionic cell bodies are located in thoracic spinal segments T1 through T12 and lumbar segments L1 through L3 or 4. Most of these neurons synapse in sympathetic ganglia in the sympathetic ganglion chain. Here, the post-ganglionic nerves originate and the post-ganglionic cell bodies are located in thc sympalhctic chain. These post-synaptic neurons travel a much longer distance than the pre-synaptic neurons, ending near the effector muscle or gland. In the parasympathetic system, the pre-ganglionic cell bodies are located in the mid-brain or medulla or the sacral regions of the spinal cord, sections S1 through S5. They synapse in ganglia far from the spinal cord, but near the effector musclc or gland. So choice 1 is incorrect. Dorsal root ganglia contain cell bodies of afferent neurons. Choice 2 is incorrect and is the location of cell bodies of the sympathetic post-synaptic neurons. Choice 3 is incorrect and is the location of pre-ganglionic parasympathetic cell bodies. So the correct answer to question is choice 4.

Front 565

Cholesterol is primarily used by mammalian cells as1. an energy storage material.2. a precursor of ketone bodies.3. a component of cell membranes.4. a precursor of polyunsaturated fatty acids.

Back 565

a component of cell membrane. Cholesterol, which can be derived from the diet or manufactured de novo in virtually all of the cells of the human body, plays a number of important roles. The first role of cholesterol is I that it is the major sterol in humans and a component of virtually all cell membranes and intracellular membranes. The second role of cholesterol is as the immediate precursor of the bile acid. The third physiological role of cholesterol is as the precursor of the various steroid hormones. So the correct answer to question is choice 3.

Front 566

Chondroitin sulfate occurs primarily in1. bile.2. blood.3. liver.4. urine.5. cartilage.

Back 566

CartilageChondroitin sulfate is in the chemical family of acid mucopolysaccharides which includes hyaluronic acid. As chondroitin 4-sulfate or chondroitin-A, and chondroitin 6-sulfate or chondroitin-C, chondroitin sulfates make up a large percentage of cartilage, bone and cornea structure. Of the other answer choices, it should be noted that a related acid mucopolysaccharide is heparin which prevents coagulation of blood and is found in arterial walls and in the lungs. So the correct answer to question is choice 5.

Front 567

Clinical adult onset diabetes mellitus (Type II) results from1. deficient secretion of insulin.2. excess secretion of epinephrine.3. failure of the kidneys to retain sugar.4. secretion of oxytocin from the posterior pituitary.5. loss of the insulin receptor function in the target tissues.

Back 567

The correct answer is choice 5, loss of the insulin receptor function in the target tissues. Non-insulin-dependent diabetes mellitus, which accounts for 80-90% of the diagnosed cases of diabetes, is also called adult onset diabetes to differentiate it from insulin-dependent juvenile diabetes. It usually occurs in middle aged, obese people. Insulin is present at near normal to elevated levels in this form of the disease. The defect in these patients lies in the loss of the insulin receptor function. Receptors are normally located on the plasma membranes of normally insulin- responsive cells, that is, hepatocytes, adipocytes and muscle cells. Insulin-dependent diabetes mellitus is also called juvenile onset diabetes or diabetes mellitus I, because it usually appears in childhood or the teens, but it is not limited to these patients. Insulin is either absent or nearly absent in this disease because of defective or absent beta cells in the pancreas. Choice 1 is incorrect. Deficient secretion of insulin would be associated with diabetes mellitus I. Choice 2 is incorrect as excess secretion of epinephrine does not lead to either form of diabetes. Choice 3 is incorrect. Sugar in the urine is due to excretion of the large quantity of plasma glucose present in diabetes. This is a normal function of the kidney. Choice 4 is incorrect. Oxytocin release is connected with uterine contraction and is not connected with either form of diabetes. So the correct answer to question is choice 5.

Front 568

Corti's organ is responsible for perception of1. light.2. sound.3. taste.4. temperature.5. proprioception.

Back 568

Sound . The organ of Corti is a spiral-shaped organ within the cochlea of the ear. It contains hair cells which are the auditory receptor cells. Sensation from the hair cells travels along the auditory or cochlear division of the vestibulocochlear acoustic nerve which terminates in the cochlear nuclei of the medulla. So the correct answer to question is choice 2.

Front 569

Decreased arterial pressure upon standing is compensated byA. decreased heart rate.B. dilation of mesenteric vessels.C. constriction of systemic arterioles.D. dilation of venules.

Back 569

Constriction of systemic arteriolesImmediately upon standing from a prone or supine position, a person's arterial blood pressure in the head and upper part of the body tends to fall. The baroreceptors located in the walls of large systemic arteries compensate by eliciting strong sympathetic discharge throughout the body resulting in constriction of systemic arterioles (Choice C) and thus raising blood pressure. Decreased heart rate (Choice A), dilation of mesenteric vessels (Choice B), and dilation of venules (Choice C) will all decrease blood pressure further which is undesirable in this case.

Front 570

Cholesterol is primarily used by mammalian cells as1. an energy storage material.2. a precursor of ketone bodies.3. a component of cell membranes.4. a precursor of polyunsaturated fatty acids.

Back 570

a component of cell membrane. Cholesterol, which can be derived from the diet or manufactured de novo in virtually all of the cells of the human body, plays a number of important roles. The first role of cholesterol is I that it is the major sterol in humans and a component of virtually all cell membranes and intracellular membranes. The second role of cholesterol is as the immediate precursor of the bile acid. The third physiological role of cholesterol is as the precursor of the various steroid hormones. So the correct answer to question is choice 3.

Front 571

Chondroitin sulfate occurs primarily in1. bile.2. blood.3. liver.4. urine.5. cartilage.

Back 571

CartilageChondroitin sulfate is in the chemical family of acid mucopolysaccharides which includes hyaluronic acid. As chondroitin 4-sulfate or chondroitin-A, and chondroitin 6-sulfate or chondroitin-C, chondroitin sulfates make up a large percentage of cartilage, bone and cornea structure. Of the other answer choices, it should be noted that a related acid mucopolysaccharide is heparin which prevents coagulation of blood and is found in arterial walls and in the lungs. So the correct answer to question is choice 5.

Front 572

Clinical adult onset diabetes mellitus (Type II) results from1. deficient secretion of insulin.2. excess secretion of epinephrine.3. failure of the kidneys to retain sugar.4. secretion of oxytocin from the posterior pituitary.5. loss of the insulin receptor function in the target tissues.

Back 572

The correct answer is choice 5, loss of the insulin receptor function in the target tissues. Non-insulin-dependent diabetes mellitus, which accounts for 80-90% of the diagnosed cases of diabetes, is also called adult onset diabetes to differentiate it from insulin-dependent juvenile diabetes. It usually occurs in middle aged, obese people. Insulin is present at near normal to elevated levels in this form of the disease. The defect in these patients lies in the loss of the insulin receptor function. Receptors are normally located on the plasma membranes of normally insulin- responsive cells, that is, hepatocytes, adipocytes and muscle cells. Insulin-dependent diabetes mellitus is also called juvenile onset diabetes or diabetes mellitus I, because it usually appears in childhood or the teens, but it is not limited to these patients. Insulin is either absent or nearly absent in this disease because of defective or absent beta cells in the pancreas. Choice 1 is incorrect. Deficient secretion of insulin would be associated with diabetes mellitus I. Choice 2 is incorrect as excess secretion of epinephrine does not lead to either form of diabetes. Choice 3 is incorrect. Sugar in the urine is due to excretion of the large quantity of plasma glucose present in diabetes. This is a normal function of the kidney. Choice 4 is incorrect. Oxytocin release is connected with uterine contraction and is not connected with either form of diabetes. So the correct answer to question is choice 5.

Front 573

Corti's organ is responsible for perception of1. light.2. sound.3. taste.4. temperature.5. proprioception.

Back 573

Sound . The organ of Corti is a spiral-shaped organ within the cochlea of the ear. It contains hair cells which are the auditory receptor cells. Sensation from the hair cells travels along the auditory or cochlear division of the vestibulocochlear acoustic nerve which terminates in the cochlear nuclei of the medulla. So the correct answer to question is choice 2.

Front 574

Decreased arterial pressure upon standing is compensated byA. decreased heart rate.B. dilation of mesenteric vessels.C. constriction of systemic arterioles.D. dilation of venules.

Back 574

Constriction of systemic arteriolesImmediately upon standing from a prone or supine position, a person's arterial blood pressure in the head and upper part of the body tends to fall. The baroreceptors located in the walls of large systemic arteries compensate by eliciting strong sympathetic discharge throughout the body resulting in constriction of systemic arterioles (Choice C) and thus raising blood pressure. Decreased heart rate (Choice A), dilation of mesenteric vessels (Choice B), and dilation of venules (Choice C) will all decrease blood pressure further which is undesirable in this case.

Front 575

Decreased response of sense organs when exposed to a constant stimulus is calledA. occlusion.B. summation.C. adaptation.D. facilitation.E. sensory deprivation.

Back 575

AdaptationA common characteristic that applies to all sensory organs is that their response to a constani stimulus decreases after a period of time. This special trait is known as adaptation (Choice C). Adaptation occurs in all sensory receptors but to different extents and by different mechanisms. Choice A occlusion as a general term refers to the act of closing or the state of being closed. It does not describe sensory organ response to stimuli. Choice B summation often refers to the additive effect of frequent repetitive stimuli applied to nerve terminals to achieve excitation. Again, it does not involve sensory organs or their response. Choice D facilitation is the enhancement or reinforcement of a nervous activity by the arrival of signals from other neurons. Choice E sensory deprivation occurs when some or all usual external stimuli are absent. It will often result in psychological stress and abnormal behavior. It also does not apply to sensory receptors response to stimuli.

Front 576

Dental plaque arises primarily as a result of enzymatic reactions using which of the following?1. Sucrose and lipid2. Sucrose and saliva3. Glucose and saliva4. Glucose and protein

Back 576

Sucrose and SalivaOne of the few dental questions on this exam, you should recognize that the major carbohydrate substrate and energy source of plaque is sucrose, not glucose. In addition, the salivary proteins are often involved in aiding the plaque to adhere to tooth structure. In general, lipids are not highly involved in plaque formation, so choice 1 is incorrect. Choices 3 and 4 are incorrect because they include glucose and not sucrose. So the correct answer to question is choice 2.

Front 577

Destruction of the cerebellum causes loss of1. memory.2. vision.3. hearing.4. muscular coordination.5. both (2) and (3) above.

Back 577

Muscular coordination The cerebellum acts to coordinate voluntary muscular activity. Choice 1 is incorrect. Memory function is located within the cerebral cortex, especially in the temporal lobes. Choice 2 is incorrect. Visual function within the brain is located within the visual cortex of the cerebrum in the occipital lobes. Choice 3 is incorrect. Hearing function is located within the cerebral cortex in the area of the auditory cortex of the temporal lobes. So the correct answer to question is choice 4.

Front 578

Development of ovarian follicles to the point of ovulation is stimulated primarily by1. estrone.2. progesterone.3. luteinizing hormone.4. follicle-stimulating hormone.5. chorionic gonadotropic hormone.

Back 578

FSH We can get this just from the name of the hormone. Ovarian follicles are stimulated, not surprisingly, by follicle-stimulating hormone or FSH from the anterior pituitary. Following ovulation, the remaining corpus luteum will be stimulated by LH or luteinizing hormone, choice 3. Choice 1, estrone, is a female sex hormone produced by the ovary, as is progesterone, choice 2. They are involved primarily in preparing and maintaining the uterine lining for implantation. Chorionic gonadotrophic hormone is produced by the placenta in the pregnant woman. It helps maintain the uterine lining during pregnancy. However, only FSH or follicle-stimulating hormone, choice 3, will stimulate the ovarian follicles.

Front 579

During an automobile accident, a child's posterior pituitary is severely damaged. Which of the following would most likely be seen?A. Addison diseaseB. Decreased skin pigmentationC. Decreased thyroid functionD. Diabetes insipidusE. Dwarfism

Back 579

Diabetes insipidusFirst, you need to know which hormones are produced in the posterior pituitary; then know the function of each hormone; and finally know which pathologic condition will follow when this "particular" hormone is absent. The posterior pituitary produces antidiuretic hormone (ADH, or vasopressin) and oxytocin. ADH is responsible for maintaining plasma osmolarity and preventing excessive water loss. When ADH is absent, diabetes insipidus can result. This condition is caused by a decrease in the renal reabsorption of water, an increase in serum osmolarity, and the generation of a dilute (hypotonic) urine. All the other conditions can result from a decrease in the secretions of the anterior pituitary. Addison disease (choice A) is caused by decreased production of corticosteroids, such as cortisol. The production is decreased secondary to a decrease in the secretion of ACTH. Decreased skin pigmentation (choice B) can occur when melanocyte-stimulating hormone is not secreted. When thyroid-stimulating hormone (TSH) is not secreted, you can expect to see a decreased thyroid function (choice C). Dwarfism (choice E) is a condition that can occur in young children when growth hormone production is decreased.

Front 580

During extended periods of fasting, all of the following are able to utilize ketones and/or fatty acids as a fuel source EXCEPTA. the brainB. cardiac muscleC. the liverD. skeletal muscleE. red blood cells

Back 580

RBCsPatterns of fuel utilization depend on the metabolic state (well-fed versus fasting) and on the individual tissue. Most cells in the body are able to utilize different fuels during the fasting state, except red blood cells. Red blood cells are only able to utilize glucose as a fuel source. Although glucose is the primary fuel for the brain (choice A), during periods of fasting, this organ can utilize ketone as an energy source. The primary source of fuel for cardiac muscle (choice B) is glucose and fatty acids. However, cardiac muscle can utilize ketones during periods of fasting. The liver (choice C) prefers to utilize glucose and amino acids; however, it can utilize glycogen, lactate, glycerol, fatty acids, and amino acids. Skeletal muscle (choice D) can utilize glucose, as well as fatty acids and ketones.

Front 581

During periods of fasting or starvation, an increased production of ketone bodies leads toA. Decreased blood pHB. DiabetesC. Increased blood pHD. Increased protein breakdownE. Skeletal muscle breakdown

Back 581

Decreased blood pH A ketone body is also referred to as a keto acid since it dissociates in solution releasing a hydrogen ion. As a result, the appearance of ketone bodies in circulation will decrease the blood pH, making it more acidic. This acidification process is referred to as ketoacidosis. Ketone bodies are produced as a result of lipid and amino acid breakdown during periods of fasting or starvation When excessive amounts of ketone bodies are formed, the pathological state known as ketoacidosis can occur. Ketoacidosis occurs most commonly in patients with diabetes (choice B). Note: Diabetes can lead to ketoacidosis, not vise versa. Ketoacidosis would not increase protein breakdown (choice D) or skeletal muscle production.

Front 582

During periods of moderate exercise, one would expect to see all of the following EXCEPTA. decreased carbon dioxide productionB. increased oxygen consumptionC. increased pulmonary blood flowD. increased ventilation rateE. no change in arterial pH

Back 582

Decreased CO2 productionDuring periods of exercise, a number of physiologic changes occur that account for the increased oxygen demand in the body. During periods of moderate exercise, one would expect to find an increased, not decreased, production of carbon dioxide. There is an increased oxygen consumption (choice B), increased pulmonary blood flow (choice C), and increased ventilation rate (choice D). In addition, there is no change in arterial pH (choice E); however, one may see a decrease in arterial pH during periods of strenuous activity.

Front 583

During red blood cell recycling each heme unit is stripped of its iron and immediately converted to:A. bilirubinB. biliverdinC. ferritinD. transferrinE. urobilin

Back 583

BiliverdinAn erythrocyte is exposed to severe mechanical stresses over the course of its life. A single round-trip of the circulatory system for an erythrocyte often takes less than 30 seconds. During this time period it is bounced off vessel walls and squeezed through tiny capillaries. With all this wear and tear and no repair mechanisms, the red blood cell has a relatively short life span. As the "old" red blood cells are broken down and recycled, each component of the hemoglobin has a different fate. For example, during this red blood cel recycling each heme unit is stripped of its iron and immediately converted to biliverdin. Biliverdin is a porphyrin derivative with a green color. The biliverdin is then converted into bilirubin (choice A) which is found in the general circulation. Liver cells absorb the bilirubin and use it to synthesize a complex molecule, conjugated bilirubin, which is excreted in the bile. Transferrin (choice D) is a plasma protein to which excessive iron is bound. Red blood cells developing in the bone marrow absorb amino acids and transferrins from circulation and use them to synthesize new hemoglobin molecules. Excessive transferrins are removed by the liver and bone marrow and the iron is then stored in two special protein-iron complexes, ferritin (choice C) and hemosiderin. Inside the large intestine, bacteria will convert the conjugated urobilin to urobilogen. When exposed to oxygen, the urobilinogen is converted to urobilin (choice E) which is the substance that gives urine its yellow color.

Front 584

During which of the following phases of the cardiac cycle are all cardiac valves open?1. Rapid filling2. Early ejection3. lsovolumic relaxation4. lsovolumic contraction5. None of these

Back 584

none of the above. During atrial systole, a small amount of blood is pumped into the ventricles. The semilunar valves are closed and the AV valves are then opened to provide a funnel for the transfer of blood from atrium to ventricle. This continues until the ventricular pressure exceeds the atrial pressure and causes the AV valves to close during ventricular systole. Ventricular systole causes the semilunar valves to open when ventricular pressure exceeds pulmonary and aortic diastolic pressure, thus beginning the period of isotonic contraction during which blood is ejected into the outflowing trunk. When pulmonary and I aortic pressures exceed end systolic ventricular pressure, it causes the semilunar valves to close. So in summary there is no point at which all valves are open at the same time. Choice 1 is incorrect. During rapid filling. AV valves are open, semilunar valves are closed. Choice 2 is incorrect. During early ejection, semilunar valves are open but AV valves are closed. Choice 3, isovolumetric relaxation, semilunar valves are closed. Choice 4, isovolumetric contraction, AV valves are closed. So the correct answer to question again, is choice 5.

Front 585

Elevated levels of calcium ions in the blood stimulates the secretion of which of the following?A. CalcitoninB. Growth hormoneC. Parathyroid hormoneD. TestosteroneE. Thyroid hormone

Back 585

Calcitonin...... is the hormone primarily responsible for the regulation of calcium ion concentrations in the blood. When blood levels of calcium ions become elevated, calcitonin is secreted to reduce calcium ion levels to normal limits. Growth hormone (choice B) stimulates cell growth and replication by accelerating the rate of protein synthesis. Parathyroid hormone (choice C) is responsible for increasing calcium ion concentrations in the body fluids; therefore, this hormone would not be secreted in an individual with hypercalcemia. Testosterone (choice D) promotes the production of functional sperm, maintains the secretory glands of the male reproductive tract and stimulates growth. The effects of thyroid hormones (choice E) are as follows: Elevation of oxygen consumption and the rate of energy consumption; increased heart rate; stimulation of activity of other endocrine glands; maintenance of sensitivity of respiratory centers as well as various other functions.

Front 586

Emotional feelings are MOST closely related to which area of the brain?A. ThalamusB. Brain stemC. CerebellumD. HypothalamusE. Limbic system

Back 586

Limbic SystemEmotional drives, motivation, and behavior are most closely associated with the limbic system of the brain (Choice E). It is located in the midbasal region of the brain. Choice A thalamus, located in the lower region of the brain, contributes to the subconscious activities of the body such as control of blood pressure and respiration. Choice B the brain stem consists of the medulla, pons, and mesencephalon. It is concerned with the motor and sensory functions for the face and head regions. Choice C the cerebellum lies above the pons and medulla and is chiefly responsible for motor coordination and body equilibrium. Choice D the hypothalamus is important in the control of autonomic body functions to maintain homeostasis.

Front 587

Energy for ATP synthesis is derived from the electron transport system by which of the following processes?1. Transamination2. Aldolization3. Reductive synthesis4. Oxidative deamination5. Oxidative phosphorylation

Back 587

oxidative phosphorylation. Oxidative phosphorylation is necessary for all cells that derive energy via aerobic oxidation. Mitochondria, the powerhouses of the cell, are the locations of the oxidative phosphorylation and electron transport enzymes. The mitochondria have two membranes, the inner membrane and the outer membrane. The inner membrane contains cytochromes b, c, c1, a and a3, and the FATP-ase associated with the mechanism of oxidative phosphorylation. Proof has been established that electron transport from NADH to oxygen is the main source of energy used for the completed phosphorylation of ADP, so the correct answer is #5, oxidative phosphorylation.

Front 588

Establishing a tracheostomy results in1. increased airway resistance.2. increased anatomic dead space.3. increased physiologic dead space.4. decreased respiratory work.5. decreased effective alveolar ventilation.

Back 588

decreased respiratory work. Anatomic dead space is that part of the conducting airway in which almost no gas exchange occurs. This includes the trachea, the main stem bronchi, and their subdivisions. This anatomic dead space is decreased by tracheostomy because of removal or bypass of some of the conducting airway. In doing so, the work of breathing which is defined as P V, pressure x the change in volume, is decreased because volume is decreased. Choice 1 is incorrect. Most of the turbulence to air flow is in the trachea and therefore bypassing the trachea results in decreased airway resistance. Choice 2 is incorrect. The trachea is part of the anatomic dead space. Tracheostomy actually decreases and not increases the anatomic dead space. Choice 3 is incorrect. Physiologic dead space = the anatomic dead space plus the volume of air that reaches the alveoli but does not come into contact with pulmonary capillary blood and therefore does not participate in gas exchange. Choice 5 is incorrect. Effective alveolar ventilation is ventilation that occurs at the gas exchange surfaces of the alveoli. A tracheostomy does not affect the effective alveolar ventilation. So the correct answer to question is choice 4.

Front 589

Excluding the effect of drugs, apnea occurring after hyperventilation of an anesthetized patient results from1. decreased demand for oxygen.2. increased cerebral blood flow.3. decreased carbon dioxide tension.4. increased hydrogen ion concentration5. decreased oxygenation of carotid bodies.

Back 589

Decreased CO2 tensionThe term "apnea" refers to respiratory arrest, a time period during which breathing ceases. Respiratory activity is stimulated by the C02 level of the blood as sensed by chemoreceptors in the medulla. It is also triggered by 02 levels as sensed by the aortic and carotid bodies. When a patient is hyperventilated, sufficient oxygen can be taken in, but excess C02 may be released from the blood. Low C02 level will then fail to stimulate the medullary chemoreceptors. Choice 1 is incorrect. Hyperventilation will not cause decreased oxygen demand. Choice 2 is also incorrect as hyperventilation does not increase cerebral blood flow. Choice 4 is incorrect. Hyperventilation will cause loss of C02 which causes acid loss or increased pH or respiratory alkalosis. Choice 5 is incorrect as well. Decreased oxygenation would not occur during hyperventilation and decreased oxygenation of thc carotid bodies should increase respiration, not cause apnea. So the correct answer to question is choice 3.

Front 590

Following an antineoplastic treatment regimen, a patient's uric acid level increases dramatically. Therefore, this individual would derive the most benefit from an agent that inhibits the action of which of the following enzymes?A. Alpha-glucosidaseB. Angiotensin-converting enzymeC. Beta-lactamaseD. CyclooxygenaseE. Xanthine oxidase

Back 590

Xanthine oxidaseAfter selected antineoplastic therapies, patients can have a high level of urate secondary to the breakdown of nucleic acids. Therefore, they are often administered allopurinol to decrease plasma urate levels. Allopurinol prevents the formation of uric-acid by inhibiting the enzymkxanthine oxidase. Decreasing uric acid levels will help prevent the formation of kidney stones, as well as block the appearance of other deleterious effects of hyperuricemia. Acarbose is an agent used in the treatment of type 2 diabetes. This agent inhibits the activity of alpha-glucosidase (choice A) in the intestinal tract, thereby helping to prevent postprandial surges of hyperglycemia. Inhibition of angiotensin-converting enzymes (choice B) will result in a lowering of blood pressure and aid in the prevention of the ventricular remodelingn that occurs secondary to congestive heart failure. Beta-lactamase (choice C) inhibitors are combined with peniciliin antibiotics to help improve their activity against bacteria that produce the enzyme beta-lactamase. Nonsteroidal antiinflammatory drugs (NSAIDs) inhibit the activity of the enzyme cyclooxygenase (choice D), thereby decreasing the production of prostaglandins.

Front 591

Following exercise, ventilation is in excess of the metabolic requirement. During this period, the level of lactic acid in blood1. increases.2. decreases.3. remains unchanged.

Back 591

decreases. Severe exercise will increase the demands on the muscle to a point where it must rely on glycolysis for the energy. Lactic acid, as a result, will be produced. This produces an acidotic state. Acidosis will increase ventilation, along with increasing the number of open capillaries, to increase surface area. An increase in the cardiac output causes an increase in the capillary blood flow. All of these factors tend to decrease the concentration of the lactic acid in the blood and return it a to its normal pre-exercise conditions. So again, the correct choice is 2.

Front 592

Following the birth of an infant, which of the following hormones is responsible for increasing milk production in the mother?A. EstrogenB. Leutinizing hormoneC. OxytocinD. ProgesteroneE. Prolactin

Back 592

ProlactinProlactin is the hormone responsible for increasing the production of milk in the mammary glands of women after the birth of a child. Note: The role of prolactin in males is poorly understood although it is believed to have a role in the regulation of androgen production. Milk is continuously secreted into the alveoli of the breasts; however, it does not flow easily from the alveoli into the ductal system. The milk is inhibited from entering the ductal system to prn,v ent the continuous leaking of milk from the breasts when the mother is not feeding. Therefore, the milk must be "let down" from alveoli to the ductal system before the baby can obtain it. Oxytocin (choice C) stimulates the myoepithelial cells in the mammary glands to express milk from the breast when a baby suckles. Aside from their other actions, both estrogen (choice A) and progesterone (choice D) aid in the development of breast tissue; however, these hormones inhibit the production of milk in the mammary glands. Luteinizing Hormone (choice B) plays an important role in causing ovulation and secretion of female sex hormones from the ovaries.

Front 593

For which of the following are the loops of Henle responsible?1. The acidification of urine2. The reabsorption of amino acids3. The reabsorption of most of the glomerular filtrate4. The formation of most of the ammonium ion excreted in the urine5. The establishment of an osmotic gradient within the medulla of the kidney

Back 593

The establishment of an osmotic gradient within the medulla of the kidneyThe major function of the loop of Henle is to reabsorb sodium ions into the cells surrounding the tubule. This absorption sets up a high concentration of solute which is then used to help in the passive reabsorption of water through the collecting tubules. Choice 1 is incorrect. Acidification of the urine occurs by hydrogen ion secretion. This occurs throughout all tubules of the kidney. Choices 2 and 3 are both incorrect. Most reabsorption, for example, of glucose and amino acids occurs in the proximal convoluted tubule. For example, more than 99% of all filtered glucose is reabsorbed in the proximal convoluted tubule. Choice 4 is incorrect. Very little ammonia is excreted by the kidney as most is changed by the liver to urea. Any ammonia in urine is the result of deamination. As a review point, remember that the reabsorption of water is through the collecting tubules and that reabsorpuon is under the control of ADH or antidiuretic hormone from the posterior pituitary. Its action is to make the collecting tubule more permeable to water therefore more reabsorption occurs and we get a more concentrated urine. So the correct answer to question is choice 5.

Front 594

Glomerular filtration rate may be determined by clearance of1. urea.2. water.3. inulin.4. glucose.5. para-aminohippuric acid (PAH).

Back 594

inulinGlomerular filtration rate or GFR is a measure of the volume per time of filtrate that leaves the glomerulus and enters the Bowman's capsule. It is measured by a material that is freely filtered into the Bowman's capsule and not reabsorbed nor secreted by any tubules. Inulin, a fructose polymer, is usually used for this purpose. Choices 2 and 4 are incorrect because they are reabsorbed from the blood in the kidney tubules. Choice 5, PAH or para-aminohippurate acid, is often used to measure renal plasma flow and is a substance freely filtered by the glomerulus but actively secreted by tubular cells. Choice 1, urea, although readily filtered into the Bowman's capsule, is more than 50% reabsorbed and readily flows into and out of certain areas of the kidney. So our correct answer to question is choice 3.

Front 595

Glycolysis begins when glucose reacts with which of the following enzymes?A. AldolaseB. HexokinaseC. PhosphofructokinaseD. Phosphoglucose isomeraseE. Pyruvate kinase

Back 595

HexokinaseGlycolysis is defined as the sequence of reactions that converts glucose into pyruvate with the concomitant production of ATP. The process of glycolysis begins when glucose reacts with hexokinase to form glucose-6-phosphate. When this compound interacts with the enzyme phosphoglucose isomerase (choice D), the compound fructose-6-phosphate is formed. Following the formation of this compound, it is interacted with the enzyme phosphofructokinase (choice C) to form the compound fructose 1,6-biphosphate. When interacted with aldolase (choice A) glyceraldehyde 3-phosphate is formed. After a number of enzymatic reactions, the compound phosphoenolpyruvate is formed. When acted upon by pyruvate kinase (choice E), pyruvate is formed and the glycolytic pathway is completed.

Front 596

Glycosaminoglycans function as important structural components of1. glycogen.2. nucleic acids.3. hyaluronidase.4. connective tissue.

Back 596

connective tissue. Glycoprotein contains carbohydrate and protein, usually more protein than carbohydrate. There is another class of glycoprotein which contains 95% or more carbohydrate. To distinguish these compounds from other glycoproteins, they are referred to as proteoglycans and their carbohydrate chains as glycosaminoglycans or GAG. There are six classes of GAG molecules now recognized. They are made up largely of disaccharide repeating units. Both their electrical charge and 1 molecular structure aid in their biological role. Choice 1, glycogen, is incorrect. Glycogen consists of alpha 1,4 or alpha 1.6-linked glucose molecules. Choice 2 is incorrect. Nucleic acids form chromatin, the material which makes up chromosomes. Choice 3, hyaluronidase, is incorrect. Hyaluronidase functions as a lubricant and support element in connective tissue. So the correct answer to question is choice 4.

Front 597

Human parotid saliva is believed to be hyposmolar because1. water is reabsorbed by excretory ducts of the gland.2. acinar cells transport water more readily than sodium ions.3. striated duct cells produce excess water and retain potassium.4. reabsorption of water by striated duct cells is less than reabsorption of sodium.

Back 597

resorption of water by striated duct cells is less than resorption of sodium. To answer this question you must have an understanding of the epithelial components of the salivary gland and the overall morphology. The epithelial components of a salivary gland, histologically, include the acini, intercalated and striated ducts and the excretory duct cells. The acinus resembles a spherical arrangement of protein-producing cells with well-developed rough endoplasmic reticulum. The product is secreted via secretory vesicles and travels through the ductile lumen, passing by the cuboidal intercalated duct cells and striated cells. The striated cells are responsible for the alteration of the fluid product. Sodium ions, chloride ions and water are removed and transported back into the blood, and potassium ions are added to the product from the blood. Thus, we have an active process and the formation of the hypo-osmolar saliva is dependent on ATP and the functioning sodium-potassium pump. In formation of saliva the resorption of water via the striated duct cells is less than the resorption of sodium. From the striated duct the salivary product passes into the excretory duct, which carries saliva into the oral cavity. Again, the correct choice is #4, resorption of water by striated duct cells is less than the resorption of sodium.

Front 598

Hypoactivity of the posterior pituitary gland leads toA. dwarfism.B. cretinism.C. acromegaly.D. diabetes insipidus.

Back 598

Diabetes insipidusThe posterior pituitary gland secretes two important hormones, oxytocin and antidiuretic hormone. Antidiuretic hormones control and regulate the concentration of water in the body fluids. A hypoactivity of the posterior pituitary gland resulting in a deficiency of antidiuretic hormone will lead to diabetes insipidus (Choice D). In this condition. the kidneys excrete larger amounts of dilute urine causing dehydration and increased concentration of sodium chloride in the extracellular fluid. Dwarfism (Choice A) is caused by deficiency of anterior pituitary secretion of GH (growth hormone) and not posterior pituitary secretion. Cretinism (Choice B) is caused by extreme hypothyroidism during fetal life, infancy, and childhood. Acromegaly (Choice C) is caused by an excessively active anterior pituitary gland, and excess GH in adulthood.

Front 599

Hypothyroidism in an adult results in1. myxedema.2. thyrotoxicosis.3. osteitis fibrosa cystica.4. increased basal metabolic rate.

Back 599

myxedemaHypothyroidism refers to an underactive thyroid which produces insufficient thyroxin. Under this condition, basal metabolism rate is low, hair is sparse, skin is yellowish and dry, and cold is not well tolerated. In adults, hypothyroidism is often termed myxedema. It is the opposite of choice 4, hyperthyroidism, which causes increased metabolic rate. Choice 2. thyrotoxicosis, is another term for hyperthyroidism. Choice 3, osteitis fibrosa cystica, refers to a bone disease caused by hyperparathyroidism. In this disease, multiple bone cysts occur. So the correct answer to question is choice 1.

Front 600

If a patient becomes excited and nervous before a tooth extraction and exhales large amounts of carbon dioxide, the most likely effect on the body would beA. Lactic acidosisB. Metabolic acidosisC. Metabolic alkalosisD. Respiratory acidosisE. Respiratory alkalosis

Back 600

Respiratory alkalosisAn important buffer system in the human body involves carbon dioxide and bicarbonate ions as seen below. C02 + H20 <-> H2CO3 <-> H+ + HC03 Alterations in the carbon dioxide and/or bicarbonate levels will result in alterations in the blood pH. Respiratory alkalosis develops when increased respiratory activity, as seen with hyperventilation, lowers plasma PCO2 levels below normal levels. The resultant effect on blood pH will be a net increase. Conversely, respiratory acidosis (choice D) develops when decreased respiratory activity, as seen with hypoventilation, increases plasma PC02 levels above normal levels. The resultant effect on blood pH will be a net decrease. Lactic acidosis (choice A) may develop following severe exercise or prolonged tissue hypoxia. The most common causes of metabolic acidosis are lactic acidosis and ketoacidosis. Metabolic acidosis (choice B) occurs when the hydrogen ions liberated by these acids overwhelm the bicarbonate buffer system leading to a net decrease in blood pH. Metabolic alkalosis (choice C) occurs when bicarbonate concentrations become elevated, leading to a net increase of blood pH.

Front 601

If a patient becomes hypotensive after the administration of a sedative before a dental procedure, which of the following reflexes should help to correct the patients low blood pressure?A. Acquired reflexB. Baroreceptor reflexC. Chemoreceptor reflexD. Hering-Breuer reflexE. Protective reflex

Back 601

Baroreceptor Reflex A reflex is defined as a rapid automatic response to a stimulus. The baroreceptor reflexes affect systemic blood pressure and stimulate the respiratory rate when blood pressure declines. For example, aortic baroreceptors monitor blood pressure within the ascending aorta. The aortic reflex, which is a baroreceptor reflex, adjusts blood pressure in response to changes at this particular location. The goal of this reflex is to maintain adequate blood flow throughout the circulatory system. An acquired reflex (choice A) is a reflex that is considered to be very complex and is a learned motor pattern. An example of an acquired reflex would be when an experienced driver steps on the brakes of the car when an animal runs in front of the vehicle. The chemoreceptor reflexes (choice C) are stimulated by changes in pH, PC02 and P02. The Hering-Breuer reflex (choice D) is composed of two different reflexes; the inflation reflex and the deflation reflex. The inflation reflex prevents over expansion of the lungs during forceful breathing and the deflation reflex inhibits the expiratory center and stimulates the inspiratory center when the lungs are in danger of collapsing. Coughing and sneezing are protective reflexes (choice E) that operate on the exposure to chemical irritants, toxic vapors or mechanical stimulation of the respiratory system. Coughing is triggered by irritation of the larynx and sneezing is triggered by irritation of the wall of the nasal cavity.

Front 602

If a person has a stroke that results in a depression of the activity in the pneumotaxic center of the pons, one would expect to seeA. Decreased apneustic center activityB. Decreased tidal volumeC. Increased pulmonary ventilationD. Increased respiratory rateE. Longer inspiratory cycle

Back 602

Longer inspiratory cycleThe apneustic center of the lower pons and the pneumotaxic center of the upper pons adjust the respiratory rate and depth of respiration in response to stimuli. In summary, the apneustic center promotes inhalation and the pneumotaxic center, which inhibits apneustic center activity, promotes exhalation. Therefore, if the activity of the pneumotaxic center is inhibited, there would be a much longer inspiratory cycle since the activity of the apneustic center cannot be inhibited. In other words, apneustic center activity would increase (choice A). Since only inspiration is promoted, the tidal volume in this person would be expected to increase (choice B). Since the respiratory rate (choice D) will decrease due to a lack of cyclic inhalations and exhalations, pulmonary ventilation would also be expected to decrease (choice C).

Front 603

If a person suffered a stoke that left them partially paralyzed on one side of the body, one would expect to see an increased number of which of the following cell types in the area of the brain affected by the stroke?A. AstrocyteB. Ependymal cellsC. MicrogliaD. OligodendrocyteE. Satellite cells

Back 603

MicrogliaIn a stroke, the blood flow to a specific area of the brain is interrupted by some kind of blockage or vascular rupture. If the circulation to a given region is interrupted for more than a few seconds the neurons will be permanently damaged. The degree of functional impairment that an individual will suffer after a stroke is determined by the duration of circulatory interruption as well as the size of the region deprived of blood. After a stroke, the nerve cells will become damaged. Therefore, one would expect to see an increased number of microglia cells in the affected area. Microglia cells are responsible for removing cellular debris, wastes and pathogens by the process of phagocytosis. Astrocytes (choice A) are glial cells that maintain the integrity of the blood brain barrier, provide structural support and regulate ion, nutrient and dissolved gas concentrations. Ependymal cells (choice B) assist in the production, circulation and monitoring of cerebrospinal fluid. Oligodendrocytes (choice D) myelinate CNS axons and provide the structural framework for the axons in the CNS. Satellite cells (choice E) are the glial cells found in the peripheral nervous system and surround the neuron cell bodies in the ganglia.

Front 604

If a person, who has lived at sea level all their life, takes a vacation to a mountain resort, which of the following physiological changes will most likely be seen in this individual after a few days?A. Decreased blood pressureB. Elevated hematocritC. Decreased PO2 in the alveoliD. Decreased ventilation rateE. Increased hemoglobin saturation

Back 604

Elevated hematocrit Both atmospheric pressure and the partial pressures of the component gasses, including oxygen, decline with increasing altitude. Individuals living at sea level normally function with an alveolar pressure around 80-90 mmHg. However, at higher elevations, the alveolar PO2 can fall to as low as 60 mmHg. Although the alveolar PO2 decreases, the body will make important physiological adjustments to compensate, such as increasing heart rate (leading to an increased blood pressure (choice A), elevated hematocrit (choice B) to account for the decreased hemoglobin saturation (choice E) as well as increasing the ventilation rate (choice D) to increase the flow of oxygen through the lungs.(Hematocrit is the percentage of the concentration of RBCs in blood. Normally 45% for men and 40% for women.

Front 605

If an agonist produces flexion, the primary action of the antagonist would beA. AbductionB. AdductionC. ExtensionD. OppositionE. Protraction

Back 605

ExtensionFlexion is described as a movement in the anterior/posterior plane that decreases the angle between the articulating extremities. For example, flexion occurs at the biceps. If an agonist produces flexion, the primary action of the antagonist would be extension, which reverses the action of flexion. Extension occurs in the same plane but increases the angle between the articulating extremities. The triceps cause extension. Abduction (choice A) is the movement away from the longitudinal axis of the body. For example, swinging the right arm to the side. Conversely, adduction (choice B) is movement toward the longitudinal axis of the body. Opposition (choice D) is the movement of the thumb that allows it to grasp and hold various objects. Protraction (choice E) is described as the movement of a given part of the body anteriorly in a horizontal plane: the grasping of ones upper lip with their lower teeth is a protracting movement.

Front 606

If an individual becomes hyponatremic, which of the following physiological responses would one expect to see?A. Increased aldosterone levelsB. Increased antidiuretic hormone releaseC. Increased thirstD. Increased water retentionE. Stimulation of the osmoreceptors

Back 606

Increased Aldosterone levelsHyponatremia is a condition where sodium ion levels in the blood are lower than normal. There are many different mechanisms through which sodium levels can be regulated. One of the primary ways in which hyponatremia occurs is through the dilutional effect of increased blood volume secondary to increased fluid intake. When sodium levels are low, one would expect to see an increased blood level of aldosterone. Aldosterone causes sodium to be reabsorbed from the filtrate in exchange for potassium. Therefore, aldosterone increases sodium ion concentrations. All of the other answer choices (situations) would be expected to be seen in an individual with hypernatremia. In hypernatremia, osmoreceptors are stimulated (choice E) which then causes antidiuretic hormone (ADH) to be released (choice B) and an increased thirst for fluid (choice C). When ADH is released there is an increased water retention (choice D), leading to an increased blood volume and a subsequent lowering of sodium ion levels.

Front 607

If an individual contracted a disease that destroyed a portion of the cells in the anterior gray horn of the lumbar region of the spinal cord, one would expect to experience which of the following?A. Decreased ability to breatheB. Decreased sensation in the handsC. Decreased sensation in the legsD. Problems with raising the armsE. Problems with walking

Back 607

Problems with walkingThe cell bodies of the neurons in the gray matter of the spinal cord contain two types of nuclei: sensory nuclei and motor nuclei. The posterior portion of the gray horn contains somatic and visceral sensory nuclei. The anterior gray horn contains somatic motor nuclei. Therefore, if an individual damages the cells in the anterior gray horn of the spinal cord, one would be expected to have a decreased ability to perform associated motor functions. Since the lumbar plexus of the spinal cord is responsible for coordinating ones ability to walk, the individual in this question would most likely have problems walking. However, since the white matter was not damaged, the sensation in the legs would not be affected (choice C). One's ability to breathe would be affected by the neurons of the cervical plexus (choice A). The sensations of the hands (choice B) and ability to move the arm (choice D) are regulated by the nerves in the brachial plexus.

Front 608

If an individual contracted travelers diarrhea and was unable to ingest carbohydrates, one would expect to see which of the following?A. Decreased gluconeogenesis in the liverB. Decreased levels of urea in the bloodC. Increased blood pHD. Increased protein metabolismE. Ketosis

Back 608

KetosisIf carbohydrates cannot be ingested for an extended period of time, the body will begin to convert both fat and protein stores into carbohydrates. Ketosis is a condition that occurs when the body increases the production of ketone bodies from the catabolism of the glucogenic and ketogenic amino acids. As mentioned before, when carbohydrate reserves have been exhausted, the body will catabolize amino acids (choice D) during the process of gluconeogenesis (choice A). Once the amino acids have been broken down, ammonia will be generated through this catabolic process. The ammonia created will be converted to urea (choice B). With the increased production of keto acids, one would expect to see a decreased blood pH (choice C).

Front 609

If an individual damaged their fifth cranial nerve, they would be expected to have an inability to perform which of the following cranial reflexes?A. Auditory reflexB. Corneal reflexC. Direct light reflexD. Tympanic reflexE. Vestibuloocular reflex

Back 609

Corneal ReflexThe cranial reflex arc involves both sensory and motor fibers of the cranial nerves. The afferent division of cranial nerve V (trigeminal nerve) is responsible for providing the corneal reflex. The cranial reflex is a somatic reflex that results in the blinking of the eye when there is contact with the corneal surface. The vestibuloocular nerve (cranial nerve VIII) coordinates three somatic reflexes: Auditory reflex, tympanic reflex and vestibuloocular reflex. The auditory reflex (choice A) is stimulated by a loud noise; the eyes and/or head will move in the direction of the sound. The tympanic reflex (choice D) is also stimulated by a loud noise. This reflex causes a reduced movement of the auditory ossicles. The vestibuloocular reflex (choice E) is stimulated by the rotation of the head. With this reflex, there is an opposite movement of the eyes in the direction of the moving head to stabilize the filed of vision. The direct light reflex (choice C) results in the constriction of the ipsilateral pupil when light is striking the photoreceptors in the eye.

Front 610

If an individual decides to go on a hunger strike and ingest only water on a daily basis, one would expect to see which of the following after approximately one week?A. Decreased urine outputB. Increased androgen levelsC. Increased glucocorticoid levelsD. Increased insulin levelsE. Increased lipogenesis

Back 610

Increased Glucocorticoid levels When individuals do not ingest nutrients for a period of time, the body goes into a metabolic state where it must rely on internal energy reserves to continue meeting its own energy demands. Approximately 12 hours each day is spent in this metabolic state. The primary focus of this state is to mobilize energy reserves and maintain normal blood glucose levels. With respect to the individual on the "hunger strike" in this question, carbohydrate reserves will become depleted several hours after the last meal. Once these reserves are depleted, the body will then focus on converting lipids and proteins into carbohydrates in an effort to maintain "normal" blood glucose levels. Increased glucocorticoid levels will have the following metabolic effects: stimulation of amino acid and lipid breakdown by the liver; protein breakdown in skeletal muscles; and gluconeogenesis and glycogenolysis in the liver. In other words, if an individual decides to go on a hunger strike and ingest only water on a daily basis, one would expect to see increased glucocorticoid levels several hours after the ingestion of the last meal. As long as the individual on the hunger strike maintains normal water intake, urine output should remain constant (choice A). In "starvation," androgen levels would be expected to decrease (choice B) because these hormones increase amino acid usage in protein synthesis. Since insulin (choice D) is responsible for decreasing blood glucose levels, one would expect to see decreased insulin levels in this individual. Lipids are being broken down in this individual, not being stored (lipogenesis) (choice E).

Front 611

If an individual had hepatitis, one would expect to seeA. Decreased clotting timeB. HyperglycemiaC. HypernatremiaD. HypoalbuminemiaE. Hypoglycemia

Back 611

hypoalbuminemiaThe liver is responsible for both metabolic and hematological regulation as well as over 200 different functions. The liver is also responsible for plasma protein synthesis. The hepatocytes synthesize and release the majority of plasma proteins in the blood, including albumin. Albumin is responsible for contributing to the osmotic concentration of the blood as well as acting as a transport protein. Therefore, in individuals with hepatitis, one would expect to see hypoalbuminemia. Since the liver is responsible for the production of various clotting factors and the storage of vitamin K, one would expect to see increased clotting times (choice A). The pancreas is responsible for the production of glucagon and insulin, which have hyperglycemic (choice B) and hypoglycemic (choice E) effects, respectively. Hypernatremia (choice C) is a condition characterized by high sodium ion concentrations; this condition often occurs in individuals with renal failure.

Front 612

If an individual ingested a large amount of medication that inhibited the liver from utilizing vitamin K, this individual would most likely experience which of the following?A. AcidosisB. AnemiaC. HemorrhageD. SeizureE. Thrombocytopenia

Back 612

Hemorrhage Both vitamin K and calcium ions affect almost every aspect of the clotting process; the intrinsic, extrinsic and common clotting pathways. Adequate amounts of vitamin K must be present for the liver to be able to synthesize four clotting factors, which include prothrombin. Without vitamin K, the entire clotting system will be inactivated. Therefore, if an individual ingested a large amount of medication that inhibited the liver from utilizing vitamin K, this individual would most likely experience some degree of hemorrhage. Hemorrhage would most likely occur because the body would be unable to stop bleeding in a traumatic event. Warfarin sodium is a medication that inhibits the action of vitamin K. Acidosis (choice A) is a condition where the blood pH is less than 7.4. Anemia (choice B) is a condition marked by a reduction in the hemoglobin and/or hematocrit content of the blood. A seizure (choice D) can be defined as a condition characterized by a sudden onset of convulsions or other epileptic symptoms. Thrombocytopenia (choice E) is characterized by an abnormally low platelet count.

Front 613

If an individual is dehydrated, one would expect to see increased production of the hormone necessary for preserving water. This hormone is produced inA. Anterior pituitaryB. HypothalamusC. PancreasD. ParathyroidE. Posterior pituitary

Back 613

HypothalamusThe hypothalamus produces antidiuretic hormone that leads to increased water reabsorption in the kidney. Therefore, if an individual is dehydrated, one would expect to see increased production of this hormone in an effort to prevent water loss. The hypothalamus also produces oxytocin, which is responsible for stimulating uterine contractions. Although both these hormones are produced in the hypothalamus, they are stored in the posterior pituitary (choice E). The anterior pituitary (choice A) produces various hormones, such as growth hormone, prolactin, adrenocorticotropin hormone, thyroid stimulating hormone, lutenizing hormone and follicle stimulating hormone, all of which do not affect blood calcium levels. The pancreas, (choice C), produces the hormones insulin and glucagon that are involved with the regulation of blood glucose levels. The parathyroid, (choice D), produces parathyroid hormone, which increases calcium blood levels in body fluids through the simulation of osteoclasts. These are large, motile multinucleated cells found on bone surfaces. When stimulated by parathyroid hormones, these cells increase blood calcium levels by the resorption of bone tissue.

Front 614

If an otherwise healthy 25 year old female had her ovaries removed, one would expect to see all of the following EXCEPTA. AmenorrheaB. Increased blood levels of estrogenC. Increased blood levels of follicle stimulating hormoneD. Increased blood levels of luteinizing hormoneE. Increased blood levels of gonadotropin releasing hormone

Back 614

Estrogen levels increaseThe ovaries are small organs located near the lateral walls of the pelvic cavity of females. These organs are responsible for the production of ova, secretion of estrogen and progestins, and the inhibition of other reproductive hormones. If the ovaries were removed, estrogen levels would decrease immediately. Estrogen is responsible for maintaining secondary sex characteristics, stimulation of the repair of the endometrium and inhibition of gonadotropin releasing hormone (GnRH) (choice E). Without estrogen, amenorrhea (choice A) will occur; this condition is characterized by a cessation of menstruation. Since estrogen inhibits the secretion of GnRH, and GnRH stimulates the secretion of both follicle stimulating hormone (FSH) (choice C) and luteinizing hormone (LH) (choice D) , one would expect to find increased blood levels of all three hormones in the absence of estrogen. Both follicle stimulating hormone and luteinizing hormone stimulate follicular development.

Front 615

If it is dangerous for an infant to ingest a product containing aspartame, he most likely has which of the following genetic disorders?A. HyperornithemiaB. HyperuricemiaC. HypervalinemiaD. PhenylketonuriaE. Wilson disease

Back 615

PhenylketonuriaThe administration of any product that contains phenylalanine, such as aspartame, to an individual with any of the hyperphenylaninemias could be detrimental to his or her general health. The hyperphenylaninemias result from an impaired conversion of phenylalanine to tyrosine. The most common and clinicaliy important is phenylketonuria, which is characterized by an increased concentration of phenylalanine in blood, increased concentration of phenylalanine and its by-products (such as phenylpyruvate, phenylacetate, and phenyllactate) in urine, and mental retardation. Phenylketonuria is a condition caused by a deficiency of phenylalanine hydrolase. Although this is a rare condition, the U.S. Food and Drug Administration requires that the following warning be placed on all food products that contain aspartame: Caution phenylketonurics - Contains phenylalanine. Hyperornithemia (choice A) is an inherited disorder of amino acid metabolism that results from a defect of the enzyme ornithine decarboxylase. This condition is associated with mental retardation, neuropsychiatric dysfunction, and protein intolerance. Hyperyricemia (choice B) is a condition associated with higher than normal blood levels of uric acid. This condition is commonly known as gout. Hypervalinemia (choice C) is an inherited disorder of amino acid metabolism that results from a defect of the enzyme valine aminotransderase. This condition is associated with mental retardation, neuropsychiatric dysfunction, and protein intolerance. Wilson disease (choice E) is an autosomal-recessive disorder associated with an abnormality of the hepatic excretion of copper resulting in toxic accumulations of the metal in the brain, liver, and other organs.

Front 616

If one individual is diagnosed with a parasitic infection and another individual is diagnosed as having an allergic reaction, one would expect to see increased blood levels of which of the following in both patients?A. BasophilsB. EosinophilsC. ErythrocytesD. MegakaryocytesE. Monocytes

Back 616

The correct answer is B. Eosinophils attack foreign objects in the body that have already been coated with antibodies. They are phagocytic cells that will engulf antibody-marked bacteria, cellular debris and parasites. Since they are sensitive to circulating allergens (substances that trigger allergies), their numbers increase during allergic reactions. Basophils (choice A) migrate to the site of injury and cross the capillary endothelium to accumulate within the damaged tissues, where they discharge their granules. These granules include histamine and heparin. Erythrocytes (choice C), or mature red blood cells, are responsible for transporting oxygen throughout the body. Megakaryocytes (choice D) form platelets, which are responsible for helping blood to "clot" when injury occurs. Monocytes (choice E) are aggressive phagocytes that engulf foreign bodies and release chemicals that attract and stimulate neutrophils and other phagocytic cells.

Front 617

If the conversion of T4 to T3 was inhibited, what physiological changes would one expect to see?A. Decreased TSH levelsB. Increased body temperatureC. Increased heart rateD. Increased thyroxine levelsE. Normal metabolic rate

Back 617

Increased thyroxine levels The thyroid gland produces large quantities of T4 (thyroxine); however, T3 (triiodothyronine) is the hormone responsible for producing the observed effects of the thyroid hormones. T4 is typically converted to T3 by enzymes in the peripheral tissues. Approximately 90% of the T3 that reaches its target cells is produced from the conversion of T4. Therefore, if the conversion of T4 to T3 were blocked, one would expect to see increased T4 (thyroxine) levels. With a decrease in the T3 levels in the blood. the body will compensate by increasing the secretion of thyroid stimulating hormone (choice A) in an effort to increase both T4 and T3 levels. Since T3 is primarily responsible for the physiological effects of thyroid hormones, one would expect to see decreased body temperature (choice B), decreased heart rate (choice C) and decreased metabolic rate (choice E).

Front 618

If the digestion of a carbohydrate results in large amounts of the monosaccharides glucose and galactose, the parent compound was most likelyA. CelluloseB. GlycogenC. LactoseD. MaltoseE. Sucrose

Back 618

lactose Prior to absorption, disaccharides and polysaccharides must be broken down into simple sugars by a variety of enzymes. For example, the enzyme lactase causes the release of a molecule of glucose and galactose from the hydrolysis of the disaccharide lactose. Cellulose (choice A) is a structural component found in many plants; the body cannot digest this compound at all. Glycogen (choice B) is a branched polysaccharide composed of interconnected glucose molecules; when this compound is broken down, many glucose molecules are formed. The enzyme maltase splits the bonds in a molecule of the disaccharide maltose (choice D) to yield two glucose molecules. Glucose and fryctose are formed when sucrose (choice E) is hydrolyzed by the enzyme sucrase.

Front 619

If the thymus decreased the production of thymosins, one would expect to see a decrease in which of the following?A. B-lymphocytesB. ComplementC. Cytotoxic T cellsD. NK cellsE. Neutrophils

Back 619

Cytotoxic T cellsLymphopoiesis (or lymphocyte production) involves the bone marrow, thymus and peripheral lymphatic tissues. The bone marrow produces hemocytoblasts which eventually generate lymphocytic stem cells responsible for &e production of lymphocytes. The lymphocytic stem cells that migrate to the thymus to differentiate into T cells do so under the influence of "thymosins" Therefore, if the thymus decreased production of thymosins, there would be a decrease in the number of T cells in the body, including cytotoxic T cells. If the lymphocytic stem cells remain in the bone marrow, they will differentiate into immature B cells (choice A) and NK (natural killer)cells (choice D). Once matured, the B cells will move to the lymph nodes and the NK cells will roam throughout the body in search of abnormal cells. Complement (choice B) is a system of circulating proteins that assists antibodies in the destruction of pathogens through the breakdown of their cell walls. Complement is not affected by thymosin secretion. Neutrophils (choice E) or PMN's attack cells or pathogens that have been "marked" with antibodies or complement proteins. The production of these cells is stimulated by colony stimulating factors, such as GSF.

Front 620

If the-action of 17-alpha-hydroxylase is inhibited, the formation of which of the following is most likely to be decreased?A. AldosteroneB. CholesterolC. CortisolD. ProgesteroneE. Testosterone

Back 620

TestosteroneWhen cholesterol (choice B) comes in contact with the enzyme cholesterol desmolase, the substance pregnenolone is formed. This compound is generally involved in two enzymatic processes. When pregnenolone is reacted with 17-alpha hydrolase, it will be converted to the compound 17-hydroxypregnenolone. After a series of enzymatic reactions, it will eventually be converted to testosterone. Therefore, if the action of 17-alpha-hydroxylase is inhibited, the formation of testosterone is most likely to be decreased. If pregnenolone is reacted with 3-beta-hydroxysteroid dehydrogenase, it will be converted to progesterone (choice D). When progesterone undergoes a series of enzymatic reactions, it can be converted to either aldosterone (choice-A) or cortisol (choice C).

Front 621

If, through a traumatic event, the blood flow to the kidneys decreases, one would expect to see which of the following?A. Decreased aldosterone secretionB. Decreased water reabsorptionC. Dilation of the efferent arterioleD. Increased renin secretionE. Increased systemic vasodilation

Back 621

Increased renin secretionThe glomerular filtration rate depends on the filtration pressure moving across the glomerular capillaries. When there is a decline in the renal blood pressure, the kidney will take several actions to increase this low blood pressure. Renin release increases when the glomerular pressure decreases or the osmolarity of f glucose the tubular fluid reaching the distal tubule decreases. Renin is a hormone released by the juxtaglomerular apparatus in the kidneys. This hormone converts the inactive protein angiotensinogen to angiotensin I. Once this occurs, a converting enzyme will convert angiotensin I to angiotensin II, which has the following physiological effects: Peripheral vasoconstriction, constriction of the efferent arteriole (choice C), stimulation of the reabsorption of sodium ions and water in the proximal tubule and triggering the release of two hormones (antidiuretic hormone and aldosterone (choice A). All of these factors serve to increase blood pressure. Decreasing water reabsorption (choice B) will further lower blood volume and blood pressure. Systemic vasodilation (choice E) will draw blood from the internal organs, including the kidneys, to the peripheral tissues.

Front 622

In a comparison of the sympathetic and parasympathetic divisions of the autonomic nervous system, all of the following are true EXCEPTA. Acetylcholine is secreted by the postganglionic fibers of both the sympathetic and parasympathetic nervous systems.B. Epinephrine is secreted by some of the ganglionic neurons in the sympathetic nervous system.C. The parasympathetic nervous system promotes energy storage and the sympathetic nervous system promotes usage of energy reserves.D. The preganglionic neurons of the sympathetic nervous system are relatively short and the preganglionic neurons of the parasympathetic nervous system are relatively long.E. The sympathetic division is primarily located between spinal segments T1 and L2 and the parasympathetic division is primarily located between spinal segments S2 and S4

Back 622

Acetylcholine is secreted by the postganglionic fibers of both the sympathetic and parasympathetic nervous systems.The correct answer is A. The sympathetic and parasympathetic divisions of the autonomic nervous system have distinctive characteristics. For example, acetylcholine is secreted by the postganglionic fibers of parasympathetic nervous system, whereas, norepinephrine is primarily secreted by the post ganglionic fibers of the sympathetic nervous system. Epinephrine is secreted by the ganglionic neurons in the sympathetic nervous system, that release this hormone directly into the circulatory system (choice B) The parasympathetic nervous system promotes energy storage (rest) and the sympathetic nervous system promotes usage of energy reserves. (fight or flight) (choice C). The preganglionic neurons of the sympathetic nervous system are relatively short and the preganglionic neurons of the parasympathetic nervous system are relatively long (choice D). With respect to general anatomy the sympathetic division is primarily located between spinal segments T1 and L2, and the parasympathetic division is primarily located between spinal segments S2 and S4 (choice E).

Front 623

In addition to causing beriberi, thiamine deficiency can lead to the development of which of the following?A. CarotenemiaB. Korsakoff syndromeC. PellagraD. Pernicious anemiaE. Scurvy

Back 623

Korsakoff syndromeBeriberi is a condition caused by a deficiency of thiamine. It typically occurs in alcoholics because of impaired absorption. Cardiovascular complications secondary to beriberi include a high-output state, biventricular myocardial failure, and retention of sodium. Another complication of thiamine deficiency is Korsakoff syndrome. This condition is mostly associated with neurologic complications. Carotenemia (choice A) results from excessive intake of vitamin A and leads to a yellowing of the skin, especially on the palms and soles. A deficiency of niacin can lead to pellagra (choice C), which is a disease typically associated with dermatitis, dementia, and diarrhea. Pernicious anemia (choice D) is a condition caused by a deficiency of vitamin B12, or cyanocobalamin. Scurvy (choice E) is caused by a deficiency of vitamin Cand can lead to perifollicular hemorrhage.

Front 624

Which of the following characterize the links between monomeric units of nucleic acids?1. Ionic bonds2. Glycosidic bonds3. Phosphodiester bonds4. Phosphotriester bonds

Back 624

3. Phosphodiester bondsThe correct answer is choice 3. Monomeric units of DNA consist of a phosphate group, deoxyribose, sugar, and nitrogen base of adenine, guanine, cytosine or thymine. These monomeric units are linked together to form the DNA strand by phosphodiester bonds. In these bonds, the 3-prime carbon of one deoxyribose links with one oxygen of the phosphate group, while a 5-prime carbon of another deoxyribose links with another oxygen of the phosphate group. This is known as a phosphodiester bond, indicating two bonds to a phosphate group. So the correct answer to question is choice 3.

Front 625

Which of the following enzymes converts trypsinogen to trypsin?A. EnterokinaseB. PeptidaseC. SecretinD. Pepsin

Back 625

A. EnterokinaseThe correct answer is Choice A. Trypsin is a powerful proteolytic enzyme present in pancreatic secretions. It aids in the digestion of proteins. When synthesized in the pancreatic cells, the proteolytic enzyme is in its inactive form trypsinogen. It is important for the enzyme to remain inactive as it will digest the pancreas itself. Trypsinogen is activated to trypsin only after it is released into the intestinal tract by enterokinase (Choice A). Enterokinase is secreted by the intestinal mucosa when chyme comes into contact with the mucosa.Peptidase (Choice B) is an enzyme present in the microvilli of the small intestine capable of splitting large polypeptides into their components.Secretin (Choice C) is a hormone secreted by duodenal and jejunal mucosa in response to high acid content in the small intestine. This hormone in turn stimulates pancreatic secretion of sodium bicarbonate.Pepsin (Choice D) is the major digestive enzyme of the gastric juices. It is active in an acidic environment to digest proteins and collagen.

Front 626

Which of the following enzymes is involved in the synthesis of fatty acids?A. Acetyl CoA carboxylaseB. Glucose 6-phosphate dehydogenaseC. Glycogen synthaseD. PhosphorylaseE. Thiolase

Back 626

A. Acetyl CoA carboxylaseThe correct answer is A. The synthesis of lipids is known as lipogenesis. Pathways of lipid synthesis begin with acetyl-CoA; these molecules can be stmng together in the cytosol yielding fatty acids. Acetyl CoA carboxylase is the key enzyme involved in fatty acid synthesis. Glucose 6- phosphate dehydogenase (choice B) is involved in the pentose phosphate pathway. The two enzymes involved in the synthesis and degradation of glycogen are phosphorylase and glycogen synthase. Furthermore, glycogen synthesis and degradation are coordinated by a hormone-triggered cascade, which ensures that when one enzyme is active, the other enzyme is inactive. The enzyme involved in glycogen degradation is phosphorylase (choice D) and the enzyme involved in glycogen synthesis is glycogen synthase (choice C), as the name implies. Thiolase (choice E) is responsible for converting acetoacetyl CoA into acetyl CoA.

Front 627

Which of the following enzymes is responsible for catalyzing the first step in fatty acid synthesis?A. Acetyl-CoA carboxylaseB. Carnitine-acyl transferaseC. Carnitine translocaseD. Fatty acid synthaseE. Lecithin cholesterol acyl transferase

Back 627

A. Acetyl-CoA carboxylaseThe correct answer is A.The enzyme responsible for catalyzing the first step in fatty acid synthesis is acetyl-CoA carboxylase. This enzyme requires the presence of both biotin and bicarbonate for converting acetyl-CoA to malonyl-CoA. Fatty acid synthase (choice D) is a multienzyme complex that catalyzes the remaining reactions for fatty acid synthesis. Carnitine-acyl transferase I (choice B) transfers the fatty acid from fatty acid acyl-CoA to carnitine to form acyl carnitine. Carnitine translocase (choice C) transports fatty acyl carnitine into the mitochondria and transports free carnitine back outside the mitochondria. Lecithin cholesterol acyl transferase (choice D) is a plasma enzyme that esterifies HDL cnolesterol.

Front 628

Which of the following functions as part of the extracellular matrix?A. MucinB. HeparinC. CollagenaseD. Chondroitin sulfateE. Dolichol phosphate

Back 628

D. Chondroitin sulfateThe correct answer is Choice D. Of the following, only chondroitin sulfate (Choice D) functions as part of the extracellular matrix. It is a proteoglycan that acts as a filler between collagen fibers and cells. Chondroitin sulfate is also a principal component in the organic matrix of bone and cartilage.Mucin (Choice A) is a mucus secretion produced by salivary glands that acts as a lubricant for surface protection.Heparin (Choice B) is a powerful anticoagulant produced mainly by the basophilic mast cells located in the pericapillary connective tissues.Collagenase (Choice C) is an enzyme that catalyzes the hydrolysis of collagen. It is not a functional part of normal extracellular matrix.Dolichol phosphate (Choice E) is a very long chain lipid that acts as a carrier for oligosaccharide.

Front 629

Which of the following groups includes only amino acids essential for humans?A. Valine, serine, leucineB. Leucine, lysine, glycineC. Tyrosine, threonine, tryptophanD. Phenylalanine, methionine, prolineE. Tryptophan, methionine, isoleucine

Back 629

E. Tryptophan, methionine, isoleucineThe correct answer is Choice E. Amino acids are the basic building blocks of proteins. They are classified into two separate groups, the essential and the nonessential amino acids. The nonessential group includes amino acids that the body can synthesize. The essential amino acid group include ones that the body either cannot synthesize or are synthesized in amounts too small to meet the needs of the body. These amino acids must be supplied in the diet. The following is a list of essential amino acids:1. Threonine2. Lysine3. Methionine4. Arginine5. Valine6. Phenylalanine7. Leucine8. Tryptophan9. Isoleucine10. HistidineOf the choices listed, Choice E (tryptophan, methionine, isoleucine) contains only essential amino acids.

Front 630

Which of the following hormones are produced by the neurohypophysis and affect contraction of smooth muscle?1. Vasopressin (ADH) and oxytocin2. Thyrotropin and intermedin3. Adrenotropin and somatotropin4. Aldosterone and luteinizing hormone

Back 630

1. Vasopressin (ADH) and oxytocinThe correct answer is choice 1. The neurohypophysis is another term for the posterior pituitary. The two major hormones produced by the posterior pituitary are ADH, also known as vasopressin, and oxytocin. ADH raises blood pressure and helps retain fluid by increasing permeability of collecting tubules in the kidney. Oxytocin causes uterine contraction and milk secretion. In choice 2, thyrotropin or TSH comes from the anterior pituitary and stimulates the thyroid gland; while intermedin or melanotropin is an anterior pituitary hormone that stimulates melanin production. And choice 3, adrenotropin or ACTH is another anterior pituitary hormone that stimulates the adrenal cortex, while somatotropin or growth hormone is another anterior pituitary hormone that stimulates overall body growth. And choice 4, aldosterone is an adrenal cortical hormone primarily responsible for sodium retention, while luteinizing hormone is an anterior pituitary hormone involved in triggering ovulation and formation of the corpus luteum. So the correct answer to question is choice 1.

Front 631

Which of the following hormones conserves body protein, carbohydrate, and fat stores?A. CortisolB. GlucagonC. InsulinD. Somatotropin

Back 631

C. InsulinThe correct answer is Choice C. Of the hormones listed, only insulin (Choice C) conserves body protein, carbohydrates, and fat stores. It inhibits the breakdown of proteins in cells, causes carbohydrates to be stored as glycogen in liver muscles, and it stimulates fat storage in adipose tissue.Cortisol, Choice A, is a potent glucocorticoid that stimulates gluconeogenesis by the liver. It also reduces cellular protein and promotes mobilization of fatty acids from adipose tissue. Glucagon is secreted by the alpha cells of the islets of Langerhans. Its primary function is to increase blood glucose concentration by stimulating breakdown of liver glycogen, and activation of adipose cell lipase making increased quantites of free fatty acids. These functions are opposite of insulin.Somatotropin, Choice D, is also known as growth hormone. It promotes growth of almost all tissues of the body by conserving carbohydrates, enhancing body proteins, and increasing utilization of fat stores for energy.

Front 632

Which of the following hormones plays a crucial role in the maintenance of normal body temperature?A. CalcitoninB. InsulinC. OxytocinD. Parathyroid hormoneE. Thyroxine

Back 632

E. ThyroxineThe correct answer is E.Thyroid hormones, such as a thyroxine and triiodothyronine, affect almost every cell in the body because they readily cross cell membranes. The effects of thyroid hormones on peripheral tissues include: elevation of oxygen consumption and the rate of energy consumption, which leads to an elevation of body temperature; increased heart rate; stimulation of activity of other endocrine tissues; maintenance of sensitivity of respiratory centers as well as various other functions. Calcitonin (choice A) is primarily responsible for decreasing of calcium ions in body tissues. Insulin (choice B) facilitates the uptake of glucose by cells and stimulates lipid and glycogen formation and storage. Oxytocin (choice C) is a hormone that promotes uterine contractions and milk ejection. The parathyroid hormone (choice D) is responsible for increasing calcium ion concentrations in the body fluids.

Front 633

Which of the following immunoglobulins is the first antibody secreted after the arrival of an antigen, and plays a role in the determination of ones blood type?A. IgAB. IgDC. IgED. IgGE. IgM

Back 633

E. IgMThe correct answer is E. In the human body, there are five classes of antibodies or immunoglobulins: IgA, IgD, IgE, IgG, and IgM. Each immunoglobulin is classified based on variations in the structure of the heavy chain constant segment. IgM is the first antibody secreted after the arrival of an antigen. When the concentration of IgG increases in the affected area, IgM levels decrease. IgM antibodies, also known as agglutinins, are responsible for the agglutination of cross-matched blood and are so used to determine an individuals blood type. IgA (choice A) is primarily found in glandular secretions and functions primarily to attack pathogens before they gain access to internal tissues. IgD (choice B) is found on the surface of B cells. These immunoglobulins help to bind antigen molecules. IgE (choice C) attaches to the exposed surfaces of basophils and mast cells. When an antigen binds to the IgE molecule, the cell is stimulated to release histamine, which is the primary cause of allergic reactions. IgG (choice D) is the largest antibody found in the body. It is responsible for providing "resistance" against many different bacteria, viruses, and bacterial toxins.

Front 634

Which of the following important nutrients is present in milk in low concentration?1. Iron2. Protein3. Calcium4. Phosphorus5. Carbohydrate

Back 634

1. IronThe correct answer is choice 1, iron. Milk is high in protein, in particular, complete protein, calcium, phosphorus and carbohydrate, particularly lactose. However, it is deficient in iron and also deficient in niacin. So the correct answer to question is choice 1.

Front 635

Which of the following is a classical decomposition reaction?A. A + B -> ABB. AB -> A + BC. A + B <-> ABD. AB <-> A + BE. AB + CD <-> AD + CB

Back 635

B. AB -> A + BThe correct answer is B. A decomposition reaction breaks a molecule into smaller fragments. The classical synthesis reaction is characterized by the symbols A + B -> AB. This shows two raw materials joining to form one molecule. Conversely, a decomposition reaction AB -> A + B (choice B) is the opposite of a synthetic reaction. Here, one molecule breaks down into two smaller components. Choices C (A + B <-> AB) and D (AB <-> A + B) are essentially the same type of reaction; an equilibrium reaction. In an equilibrium reaction there is a decomposition reaction followed by a synthesis reaction or vise versa. These reactions occur on a continual basis and are reversible. The reaction AB + CD <-> AD + CB is termed an exchange reaction because the two initial compounds (AB and CD) decompose and form two different compounds (AD and CB) usually by exchanging ions.

Front 636

Which of the following is a principal action of insulin?1. To mobilize lipid deposits2. To enhance cell permeability to glucose3. To decrease cell permeability to glucose4. To conserve glucose by breaking down amino acids

Back 636

2. To enhance cell permeability to glucoseThe correct answer is choice 2. Insulin acts primarily to reduce blood glucose levels. It is made by beta cells in the pancreas. Its actions include increasing cell permeability to glucose in fat tissue and muscle; therefore, glucose is taken out of the blood by these tissues. It also increases fatty acid synthesis by fat tissue and glycogen synthesis by the liver. It also decreases the release of gluconeogenic amino acids by the liver and decreases protein breakdown. So choices 1, 3 and 4 are incorrect and opposite. Insulin will tend to cause formation, not degradation, of lipids; increase, not decrease, cell membrane permeability to glucose; and cause decreased, not increased, breakdown of amino acids. So the correct answer to question is choice 2.

Front 637

Which of the following is a reflex mediated by the vagus?1. Bile flow from the liver2. Mucus secretion from the Brunner's glands3. Cephalic phase of gastric secretion4. Pancreatic secretion of bicarbonate

Back 637

3. Cephalic phase of gastric secretionThe correct answer is choice 3. The vagus nerve functions primarily to promote digestion. It increases acid production in the stomach. Selective vagotomy is sometimes utilized as a treatment for chronic gastric ulcers. Choice 1, bile flow from the liver, is incorrect. The vagus nerve causes contraction of the gallbladder, not the liver, to increase bile flow. Choice 2, mucus secretion from the Brunner's glands, is incorrect. Mucus secretion in the duodenum is stimulated by the presence of gastrin, secretin and cholecystokinin. Choice 4, pancreatic secretion of bicarbonate, is incorrect. Pancreatic secretion of bicarbonate is under the control of secretin. So the correct answer to question is choice 3.

Front 638

Which of the following is MOST likely to cause respiratory acidosis?A. Moving from high altitude to sea levelB. Untreated diabetes mellitusC. HypoventilationD. Kidney failureE. Vomiting

Back 638

C. HypoventilationThe correct answer is Choice C. Respiratory acidosis is a condition caused by retention of C02 due to abnormal or inadequate pulmonary ventilation. This may be a result of pathologic conditions that damage the respiratory centers in the brain or that decrease the lung's ability to eliminate C02 such as obstruction or pneumonia.Of the following choices, hypoventilation (Choice C) is the most likely cause of respiratory acidosis as discussed above. Inadequate pulmonary ventilation increases H2CO3 and hydrogen ion concentration in the blood resulting in acidosis.Moving from high altitude to sea level (Choice A) will not cause respiratory acidosis. Respiratory alkalosis, however, may occur when a person ascends from sea level to high altitude.Untreated diabetes mellitus (Choice B) may result in acidosis but it is caused by pathologic levels of insulin and not by an abnormality in respiration.Kidney failure (Choice D) can lead to acidosis resulting from failure of the kidney to eliminate acidic products from the body. It is also not a cause of respiratory acidosis.

Front 639

Which of the following is NOT a monosaccharide?1. Amylose2. Glucose3. Fructose4. Glyceraldehyde5. Glucuronic acid

Back 639

1. AmyloseThe correct choice to question is #1, amylose. Amylose is an unbranched polyglycan of starch. It is not a monosaccharide. You should know that both glucose, C6H12O6 is a monosaccharide, and fructose is also a monosaccharide. Remember, a monosaccharide is a carbohydrate that cannot form any simpler sugar by simple hydrolysis. The pentoses and hexoses are monosaccharides. Both glyceraldehyde and glucuronic acid are also monosaccharides. So again, the correct choice to question is #1, amylose.

Front 640

Which of the following isa present in plasma but absent in serum?1. Albumin2. Globulin3. Lecithin4. Fibrinogen5. Prothrombin

Back 640

4. FibrinogenThe correct answer is choice 4. And we will shortly bring up a problem with answer choice 4, but let's review the choices anyway. Plasma is the fluid noncellular portion of the blood containing water, various ions, inorganic compounds, proteins and other organic compounds. If whole blood is allowed to clot and the clot is removed, the remaining liquid is known as serum. Serum has essentially the same composition as plasma, except that fibrinogen and various clotting factors -- in particular II, V and VIII -- have been removed. Plasma and serum do have similar composition in terms of albumin, globulin and lecithin. In what appears to be an oversight, prothrombin, also known as clotting Factor II, is removed from plasma when clotting occurs and should apparently be viewed as another correct answer to question. So anyway, the official answer is choice 4, but choice 5 is also physiologically correct.

Front 641

Which of the following is responsible for protecting tooth enamel and binding toxic tannins?A. High-proline proteinB. immunoglobulin AC. KallikreinD. LysozymeE. Mucins

Back 641

A. High-proline proteinThe correct answer is A.High-proline proteins are responsible for protecting tooth enamel nd binding toxic tannins. lmmunoglobulin A (choice B) helps defend against bacteria on mucosal surfaces. Kallikrein (choice C) is a proteolytic enzyme that cleaves kininogens to form bradykinin. Lysozymes (choice D) break down the cell walls of bacteria. Mucins (choice E) are glycoproteins that lubricate the food and protect buccal and esophageal mucosa from scratching.

Front 642

Which of the following is responsible for secreting substances that have a basic pH?A. CholecystokininB. GastrinC. Hydrochloric acidD. Intrinsic factorE. Secretin

Back 642

E. SecretinThe correct answer is E.Secretin is synthesized and stored in the S cells of the upper intestine. It stimulates the secretion of bicarbonate-containing substances from the pancreas and inhibits gastric emptying and gastric acid production. Bicarbonate containing sutistances are "basic" by chemical nature. Cholecystokinin (choice A) is produced and stored in the cells of the duodenal and jejunal mucosa. The parietal cell secretes two substances: intrinsic factor and hydrochloric acid. The hormone gastrin (choice B), which is produced in the G cells of the duodenum, primarily functions to stimulate hydrochloric acid, histamine, and pepsinogen secretion, as well as increase gastric blood flow. Hydrochloric acid (choice C) functions primarily to denature proteins and activate digestive enzymes. Intrinsic factor (choice D) is the secretion of parietal cells that facilitates the absorption of vitamin B12 across the intestinal lining. Vitamin B12 is a member of the cobalamin family and serves as a cofactor for two reactions in humans: the methylation of homocysteine to methionine and conversion of methylmalonyl-CoA to succinyl-CoA. The most common disorder seen with vitamin B12 deficiency is pernicious anemia, which is associated with the development of a megaloblastic anemia.

Front 643

Which of the following is the major building block, comprising greater than 50%, of all biologic membranes?A. CholesterolB. GlycolipidsC. Integral membrane proteinsD. Peripheral membrane proteinsE. Phospholipids

Back 643

E. PhospholipidsThe correct answer is E.Lipids are the primary constituents of all biologic membranes. Phospholipids are the major building block of all biologic membranes, comprising between 50% and 60% of the total membrane lipid. Although cholesterol (choice A) is a major component of plasma membranes, it comprises between 15% and 25% of the total membrane. Glycolipids (choice B) generally make up the remainder of the lipid portion of the cell membrane. Integral membrane proteins (choice C) are embedded in the lipid bilayer and cannot be removed without disrupting the membrane. Peripheral membrane proteins (choice D) are also found in the lipid-based membrane; however, these proteins can be removed.

Front 644

Which of the following is the major contributor to colloid osmotic pressure?1. Albumin2. Alpha globulin3. Beta globulin4. Gamma globulin

Back 644

1. AlbuminThe correct choice is #1, albumin. Plasma osmotic pressure is a direct result of plasma proteins in the bloodstream. Plasma proteins such as albumin have osmotic activity because of their inability to permeate the membrane. They are the most abundant protein relative to globulins and fibrinogen: therefore, due to their abundance they are the major contributors to osmotic colloidal pressure. The effective colloidal osmotic pressure is 25 mmHg. This may decrease or increase in plasma as the concentrations of plasma proteins vary. Alpha globulin, beta globulin and gamma globulin are not in abundance relative to albumin, and therefore are not major contributors to the colloid osmotic pressure. Again, the correct choice is #1, albumin.

Front 645

Which of the following is the region/nucleus of the hypothalamus responsible for controlling the feeding reflexes, such as swallowing and licking?A. Mamillary bodiesB. Paraventricular nucleusC. Preoptic areaD. Supraoptic nucleusE. Tuberal area

Back 645

A. Mamillary bodiesThe correct answer is A. The hypothalamus contains a variety of important control and integrative centers as well as those associated with the limbic system. The mamillary bodies are the region of the hypothalamus responsible for controlling the feeding reflexes, such as swallowing and licking. The paraventricular nucleus (choice B) is responsible for secreting oxytocin. The preoptic area (choice C) is responsible for regulating body temperature. The supraoptic nucleus (choice D) secretes Antidiuretic hormone, which restricts water loss in the kidneys. The tuberal area (choice E) is the portion of the hypothalamus that releases hormones that control the endocrine cells of the anterior pituitary.

Front 646

Which of the following minerals is responsible for the proper functioning of the enzyme carbonic anhydrase?A. CopperB. MagnesiumC. ManganeseD. PhosphorusE. Zinc

Back 646

E. ZincThe correct answer is E. Minerals (and vitamins) are essential components of the diet because the body is unable to synthesize the majority of these compounds. Minerals are inorganic ions typically released through the dissociation of electrolytes. Zinc is a mineral responsible for the proper functioning of the enzyme carbonic anhydrase and acts as a cofactor of various other enzyme systems. When individuals are zinc deficient, the immune system may become compromised. Copper (choice A) acts as a cofactor for hemoglobin synthesis. Magnesium (choice B) is a cofactor of enzyme systems and is responsible for normal membrane functioning. It is also a constituent of bones and teeth. Manganese (choice C) is also a cofactor for various enzyme systems; however, it is not involved with the enzyme carbonic anhydrase. Phosphorus (choice D) is a constituent of bones, teeth, and ATP phosphorylated metabolic intermediates.

Front 647

Which of the following must be digested before being in a form that can be absorbed by enterocytes?A. MonoglyceridesB. Fatty acidsC. FructoseD. GlycineE. Maltose

Back 647

E. MaltoseThe correct answer is Choice E. Foods from which the human body obtains nutrition can be classified into carbohydrates, fat, and proteins. These substances generally cannot be absorbed by the intestinal mucosa without the process of digestion. Carbohydrates, for example, are mainly large disaccharides and polysaccharides that must be hydrolyzed before they can be utillized by the enterocytes of the small intestine. Maltose (Choice E), a disaccharide found in starch that must be split into its constituent monosaccharide before it can be absorbed by the enterocytes.Monoglycerides (Choice A) and fatty acids (Choice B) are the digestive end products of fat. They are both readily (glucose) absorbable by enterocytes.Fructose (Choice C) is one of the monosaccharides formed from digestion of cane sugar. It is already in a form that can be absorbed by enterocytes via facilitated diffusion. Glycine (Choice D), an amino acid, can also be absorbed directly by enterocytes without further digestion.

Front 648

Which of the following occurs in a normal menstrual cycle?1. Ovulation generally occurs 10 days from the beginning of the cycle.2. The ovum generally disintegrates or becomes nonviable if it is not fertilized within four days.3. The blood concentration of estradiol increases as the corpus luteum develops.4. The blood level of follicle-stimulating hormone increases and the level of luteinizing hormone decreases at the time of ovulation.

Back 648

2. The ovum generally disintegrates or becomes nonviable if it is not fertilized within four days.The correct answer is choice 2. Nonfertilized ova will generally degenerate within about four days. Choice 1 is incorrect. Ovulation occurs approximately on the 14th day of the cycle, although the exact time will vary. Choice 3 is incorrect. Estradiol, or estrogen, secreted by the ovary will decrease as the corpus luteum develops. The corpus luteum formed after ovulation secretes large amounts of progesterone and much smaller amounts of estrogen than at the peak of the follicular stage. Choice 4 is incorrect and opposite. Slightly before ovulation, FSH levels decline and then slowly rise, while LH levels rise dramatically in a spike-like fashion. The great increase in LH, or luteinizing hormone, is largely responsible for ovulation. So the correct answer to question is choice 2.

Front 649

Which of the following occurs last in the generation of an action potential?A. Sodium ions enter the cellB. The transmembrane potential goes from - 70 mV to + 30 mVC. Voltage-regulated potassium channels openD. Voltage-regulated sodium channels closeE. Voltage-regulated sodium channels open

Back 649

C. Voltage-regulated potassium channels openThe correct answer is C. Action potentials are propagated changes in the transmembrane potential that spread across an entire excitable membrane . In a given neuron, an action potential usually begins at the initial segment of the axon and is conducted along the length of the axon. The steps in the generation of an action potential are as follows: A graded depolarization brings an area of excitable membrane to a threshold. The voltage regulated sodium channels open (choice E) which permits sodium ions to enter the cell (choice A). Once this occurs, the transmembrane potential goes from - 70 mV to + 30 mV (choice B). The voltage-regulated sodium channels then close (choice D) and the voltage regulated potassium channels open (choice C). In other words, the opening of the potassium channels is the last step that occurs based on the given answer choices. Once the potassium channels open, potassium ions move out of the cell and repolarization begins.

Front 650

Which of the following portions of the cardiovascular system contains the greatest volume of blood?A. ArteriolesB. CapillariesC. Systemic veinsD. Chambers of the heartE. Pulmonary vasculature

Back 650

C. Systemic veinsThe correct answer is Choice C. The greatest volume of blood by far is contained in the systemic veins (Choice C). It comprises 64% of blood in the systemic circulation. The veins serve as a major reservoir of blood for the body along with their important function as conduits for transport of blood from tissues back to the heart.The arterioles (Choice A) and capillaries (Choice B) carry approximately 7% of the blood.The chambers of the heart (Choice D) also contain 7% of the blood.The pulmonary vasculature (Choice E) holds 9% of blood volume.

Front 651

Which of the following portions of the nephron has a primary function of only reabsorbing water from filtrate?A. Ascending loop of HenleB. Collecting tubulesC. Descending loop of HenleD. Distal convoluted tubuleE. Proximal convoluted tubule

Back 651

B. Collecting tubulesThe correct answer is B. The primary function of the nephron is to clear the plasma of unwanted substances as it passes through the kidney. Since plasma contains both wanted and unwanted substances, the nephron will selectively reabsorb these "wanted" substances, at selected portions of the nephron, back into the plasma and the remaining components are subsequently excreted into the urine. The descending loop of Henle (Choice C) and the ascending loop of Henle (choice A) are primarily responsible for the reabsorption of ions and assisting in the creation of the medullary concentration gradient. The collecting tubules (choice B) are primarily responsible for the resorption of water, under the control of the hormone ADH. The distal convoluted tubule (choice D) is the primary site for secretion of substances into the filtrate as well as some reabsorption of water and sodium ions. The primary site of nutrient reabsorption in the nephron is the proximal convoluted tubule (choice E).

Front 652

Which of the following reflexes complements the withdrawal reflex by making compensatory adjustments on the opposite side of the body receiving the stimulus?A. Crossed extensor reflexB. Flexor reflexC. Patellar reflexD. Stretch reflexE. Tendon reflex

Back 652

A. Crossed extensor reflexThe correct answer is A. Reflexes are classified according to the site where the information is being processed, the nature of the resulting motor response or the complexity of the neural circuit involved. The crossed extensor reflex is classified as a contralateral reflex because of the motor response that occurs on the opposite side of the body from that receiving the stimulus. For example, if one were to step on a nail, the flexor reflex (a type of withdrawal reflex) would pull the foot away from the nail and the crossed extensor reflex would "stiffen" the other leg to support the body. As previously mentioned, the flexor reflex (choice B) will "flex" the muscles in the affected limb to pull away from the painful stimulus. The patellar reflex (choice C) is a type of stretch reflex (choice D) that results in a reflexive kick when properly stimulated. The stretch reflex provides automatic regulation of muscle length. The tendon reflex (choice E) prevents a muscle from exerting too much tension.

Front 653

Which of the following represent(s) the matrix proteins of enamel?A. Carboxylglutamic acid containing proteinsB. Type I collagenC. AmelogeninsD. ProteoglycansD. Elastin

Back 653

C. AmelogeninsThe correct answer is Choice C. As discussed, the human tooth enamel is made up of approximately 95-98% of inorganic matter by weight. The remaining structure is composed of an organic matrix and water. Protein such as amelogenin (Choice C) is formed in the matrix.Choice A, carboxylglutamic acid containing protein, is not found in enamel.Choice B, type 1 collagen, is found in skin, tendon, bone and cornea but does not represent matrix protein of enamel.Choice D proteoglycans along with extracellular fluid make up the ground substances in bone.Choice E elastin is also a connective tissue protein. It is the major component of elastic fibers that can stretch to several times their length. Large amounts of elastin are found in the walls of blood vessels and ligaments. It is not present in enamel.

Front 654

Which of the following represents a soluble polysaccharide found in dental plaque and is formed from the fructose moiety of sucrose?1. Levan2. Dextran3. Amylopectin4. Hyaluronic acid

Back 654

1. LevanThe correct answer is choice 1, levan. Levan is a polyfructose synthesized by plaque bacteria. Levan is a stimulator of B cells and individuals with periodontal disease exhibit greater response to this polysaccharide than do normal control individuals. Choice 2, dextrans is incorrect. Dextrans are water soluble, high molecular weight glucose polymers. Choice 3, amylopectins, is incorrect. Amylopectins are branched chain polyglucose molecules or glucans. Choice 4. hyaluronic acid, is incorrect. This is a component of the ground substance that makes up the intercellular matrix of the gingival connective tissue. So the correct answer to question is choice 1.

Front 655

Which of the following represents the amount of dietary calcium normally absorbed from the gut of an adult man?1. An amount less than 50%2. An amount between 60-70%3. An amount between 80-100%4. An amount dependent upon the mucosal ferritin level

Back 655

1. An amount less than 50%The correct answer is choice 1, an amount less than 50%. Less than 50% of the dietary calcium is absorbed through the small intestine via active transport. This active transport is mediated by a carrier synthesized from vitamin D. Choices 2 and 3 are therefore incorrect. Choice 4 is incorrect. Ferritin is responsible for the transport of iron in the bloodstream and is not connected to the transport of calcium. So the correct answer to question is choice 1.

Front 656

Which of the following represents the chemical substance that is the immediate source of energy for muscle contraction?A. GlycogenB. AcetylCoAC. Lactic acidD. Creatine phosphateE. Adenosine triphosphate

Back 656

E. Adenosine triphosphateThe correct answer is Choice E. When a muscle contracts, work is performed and energy is required for this process. The immediate source of energy is provided by the cleavage of adenosine triphophate (ATP) (Choice E) to form adenosine diphosphate (ADP). The concentration of ATP present in muscle fibers is limited and only sufficient to maintain full contraction for 1 to 2 seconds. As muscle contraction continues, creatine phosphate (Choice D) is used to rephosphorylate ADP to form new ATP. The amount of creatine phosphate, however, is also limited. It will carry the muscle contraction for another 3-5 seconds. Glycogen (Choice A) is then used to reconstitute both ATP and creatine phosphate.So though both glycogen (Choice A) and creatine phosphate (Choice D) are important energy sources during muscle contraction, they are not the initial or immediate source of energy.Acetyl CoA (Choice B) reacts in the citric acid cycle to release large amounts of energy to convert ADP to ATP in the mitochondria. It is not, however, used by the muscle during its contraction. Lactic acid (Choice C) is an end product in the breakdown of glycogen. It is also not a primary energy source.

Front 657

Which of the following spinal tracts controls the involuntary regulation of eyes, head, neck and upper limb position in response to either a visuai or auditory stimulus?A. Corticobulbar tractB. Reticulospinal tractC. Rubrospinal tractD. Tectospinal tractE. Vestibulospinal tract

Back 657

D. Tectospinal tractThe correct answer is D. In the extrapyramidal spinal tract are the following: The tectospinal tract controls the involuntary regulation of eye, head, neck and upper limb position in response to either a visual or auditory stimulus. The reticulospinal tract (choice B) controls the involuntary regulation of reflex activity and autonomic function. The rubrospinal tract (choice C) controls the involuntary regulation of posture and muscle tone. The vestibulospinal tract (choice E) controls the involuntary regulation of balance and muscle tone. The pyramidal portion of the spinal tracts contain the corticobulbar (choice A), lateral corticospinal and anterior corticospinal tracts. All three tracts are involved in the voluntary motor control of the skeletal muscles.

Front 658

Which of the following substances represents an unsaturated fatty acid?A. CholesterolB. PalmitateC. StearateD. CholineE. Oleate

Back 658

E. OleateThe correct answer is Choice E. Fatty acids are long-chain hydrocarbon organic acids. An unsaturated fatty acid is one in which its carbon chain contains one or more double or triple bonds capable of absorbing additional hydrogen atoms. Oleate (Choice E) is an 18 carbon chain unsaturated fatty acid with one double bond in the middle of the chain.Cholesterol (Choice A) is one of the most abundant lipids in the body. It does not contain fatty acids.Palmitate (Choice B) is a 16-carbon chain fatty acid that is fully saturated.Stearate (Choice C) is an l&carbon fatty acid fully saturated with hydrogen atoms.Choline (Choice D) is a relatively small hydrophilic compound essential in the formation of some phospholipids such as a lecithin. It is not a fatty acid.

Front 659

Which of the following tissues is primarily responsible for formation of urea?1. Liver2. Brain3. Kidney4. Muscle

Back 659

1. LiverThe correct choice is #1, the liver. Nitrogen is excreted predominantly in the form of urea in urine. Urea is formed in the liver, brain and also the kidney, but mainly in the liver via the urea cycle. Let us review this very important cycle. C02 and NH3 + H20 + 2ATP via carbamoylphosphate synthetase form the unstable carbamoylphosphate. Carbamoylphosphate combines with ornithine, via ornithine carbamoyltransferase to form citrulline. Citrulline and aspartate and ATP form arginosuccinate, then fumarate and arginine, via arginosuccinate lyase. Arginine is then hydrolyzed via arginase to form the urea, NH2-CO-NH2 and H2. The net reaction of the urea cycle is C02 + 2NH3 + 3ATP + 3H20 -> urea + 2ADP + AMP + 4inorganic phosphates. So again, the correct choice is #1, the liver.

Front 660

Which of the following vitamins can be supplied to humans by the normal action of intestinal flora?1. A2. D3. E4. K5. None of the above

Back 660

4. KThe correct choice is #4, vitamin K. Vitamin K can be supplied to humans by the normal action of intestinal flora. Vitamin K is a key factor in the synthesis of prothrombin. In the absence of vitamin K or in the presence of dicumarol or warfarin prothrombin is not produced. Prothrombin binds to calcium, and in the presence of these antagonists of vitamin K it does not bind to calcium. Prothrombin, via activated factor X is converted into thrombin. This is modified by factor V. When calcium binds to prothrombin it increases its affinity to the phospholipid membranes from platelets of injury. This binding then brings the prothrombin into proximity of factors Xa and V, which are also involved in the clotting cascade. Thrombin, in turn, converts fibrinogen to fibrin for the final step in the clotting cascade. So again, the correct choice to question is 4, vitamin K.

Front 661

Which of the following vitamins is the LEAST likely to be involved in tooth development and substance that is the immediate source of calcification?1. A2. B13. C4. D

Back 661

2. B1The correct answer is Choice B. Tooth development and calcification are similar to that of bone. They are affected by various factors of metabolism such as the availability of calcium and phosphate in the diet, and rate of secretion of thyroid, growth, and parathyroid hormones. Vitamins are also essential in the formation of teeth. Vitamin A (Choice A) is necessary for normal growth and proliferation of epithelial cells, vitamin C (Choice C) activates prolyl hydroxylase which promotes normal formation of collagen, and vitamin D (Choice D) increases calcium absorption and helps control calcium deposition in hard tissues. Choice B, Vitamin B1,is least likely to be involved in tooth development since it functions as a cocarboxylase specifically needed in the final metabolism of carbohydrate and amino acids.

Front 662

Which type of muscle contraction occurs when there is a change in length of the muscle with a corresponding change in tension on that muscle?A. ConcentricB. DynamicC. EccentricD. IsometricE. Isotonic

Back 662

B. DynamicThe correct answer is B.A dynamic contraction includes both concentric and eccentric types of contractions. In general, a dynamic contraction results in a change in length of the muscle, with a corresponding change in tension on that muscle. A concentric contraction (choice A) is a type of dynamic contraction in which the muscle fibers shorten and the tension on the muscle increases. An eccentric contraction (choice C) is a type of dynamic contraction in which the muscle fiber lengthens and the tension on the muscle increases. An isometric contraction (choice D) occurs when both ends of the muscle are fixed and no change in length occurs during the contraction, but the tension increases. An isotonic contraction (choice E) occurs when a muscle shortens against a fixed load while the tension on that muscle remains constant.

Front 663

With respect to a normal kidney, which of the following situations would cause the glomerular filtration rate to increase?A. Constricting the afferht arterioleB. Decreasing blood flow to the kidneysC. Decreasing plasma protein concentrationsD. Decreasing renin levelsE. Sympathetic stimulation of the kidney

Back 663

C. Decreasing plasma protein concentrationsThe correct answer is C. The glomerular filtration rate is the amount of filtrate produced in the kidneys each minute. The average glomerular filtration rate is around 125 mL of filtrate per minute. There are many different factors that can affect the glomerular filtration rate. For example, when the blood volume is increased, due to increased water intake, the normal concentration of plasma proteins in the blood will be decreased. This relative decrease can be attributed to the dilutional effect of increased fluid volume. Therefore, when plasma protein concentrations are decreased, the kidneys will increase the glomerular filtration rate (GFR) to increase the production of urine. Constricting the afferent arteriole (choice A) will directly decrease the GFR as less blood enters the nephron. Constriction of the afferent arteriole often occurs when there is a fall in blood pressure or when there is sympathetic stimulation of the kidney (choice E). When blood flow to the kidneys decreases (choice B), the GFR will naturally decrease because there is not as much fluid being presented to the kidneys per unit of time. Decreased renin levels (choice D), leads to a decrease in the conversion of angiotensin I to angiotensin II. Since angiotensin II is a potent constrictor of the efferent arteriole, decreasing renin levels will decrease the GFR.

Front 664

With respect to catabolism of amino acids, deamination results in the production ofA. keto acidB. acetyl-CoAC. ammoniaD. carbon dioxideE. urea

Back 664

C. ammoniaThe correct answer is C. The first step in the catabolism of an amino acid is the removal of the amino group. The process requires a coenzyme derivative (vitamin B6). The amino group can be removed by deamination or transamination. Deamination is performed in the preparation of an amino acid for breakdown in the TCA cycle. In deamination, an amino group is removed and ammonia is generated. In the process of transamination, the amino group of a given amino acid is transformed to a keto acid (choice A). A keto acid resembles an amino acid except that the second carbon is bound to an oxygen rather than an amino group. Acetyl-CoA (choice B) is produced by the breakdown of pyruvic acid and the addition of an acetyl-group to these byproducts. Note: Acetyl-CoA is produced only in aerobic glycolysis. In the absence of oxygen, the pyruvic acid is converted to lactic acid. Carbon dioxide (choice D) is produced in the TCA cycle. The ammonia produced during deamination is toxic; therefore, the liver metabolizes the ammonia molecule to urea (choice E), which is a relatively non-toxic, water-soluble compound that is excreted in the urine.

Front 665

With respect to the coagulation phase of homeostasis, the intrinsic pathway involvesA. Clotting factors VII, IX, XI and XIIB. ProstacyclinC. Thrombin and fibrinD. Thromboxane A2 and platelet factorsE. Tissue factor and tissue thromboplastin

Back 665

A. Clotting factors VII, IX, XI and XIIThe correct answer is A. The coagulation phase of homeostasis has three primary pathways for stimulation of blood clotting: The intrinsic pathway, the extrinsic pathway, and the common pathway. The intrinsic pathway begins with the activation of proenzymes exposed to collagen fiber located at the site of the injury and involves the clotting factors VII, IX, XI and XII (choice A). This pathway, after a series of linked reactions, forms a complex called platelet thromboplastin. The common pathway begins when the thromboplastin from both the intrinsic and extrinsic pathways appears in the plasma. After a series of reactions, prompted by these compounds, thrombin completes the coagulation process by converting fibrinogen to fibrin (choice C). The platelet phase, begins within seconds after the injury, and causes platelet adhesion to the exposed surfaces of the site of injury. Once platelets arrive at the site of injury, they begin releasing thromboxane A2 and platelet factors (choice D) which stimulate platelet aggregation and vascular spasms. The platelet phase is regulated by prostacyclin (choice B), which inhibits platelet aggregation. The extrinsic pathway is part of the coagulation phase of homeostasis and begins about 30 seconds after the traumatic event. The extrinsic pathway begins with the release of tissue factor, which combines with calcium and another procoagulant, to form tissue thromboplastin (choice E).

Front 666

With respect to the physiological movement of a body part, abduction is best described asA. the movement away from the longitudinal axis of the bodyB. the movement of a structure in a superior directionC. the movement in the anterior/posterior plane that decreases the angle between the articulating extremities.D. the movement of the thumb which allows it to grasp and hold various objectsE. the movement of a given part of the body anteriorly in a horizontal plane

Back 666

A. the movement away from the longitudinal axis of the bodyThe correct answer is A. Abduction is the physiological movement away from the longitudinal axis of the body. For example, swinging the right arm to the side. Elevation occurs when a structure moves in a superior direction (choice B). Conversely, depression occurs when a structure moves in a inferior direction; the process of chewing is a repetitive cycle of depressing and elevating the mandible. Flexion (choice C) is described as a movement in the anteriorlposterior plane that decreases the angle between the articulating extremities: for example, flexion of the biceps. Opposition (choice D) is the movement of the thumb that allows it to grasp and hold various objects. Protraction (choice E) is described as the movement of a given part of the body anteriorly in a horizontal plane; the grasping of ones upper lip with their lower teeth is a protracting movement.

Front 667

With respect to types of muscle contractions, treppe is a situation whereA. A muscle is producing peak tension during rapid cycles of contraction and relaxationB. A muscle is stimulated so frequently that the relaxation phase is completely eliminated.C. A muscle is stimulated repeatedly for several seconds with a constant stimulus; the amount of tension produced then gradually increases to a maximum.D. A second stimulus arrives before the relaxation phase has ended and a second and a more powerful contraction occurs.E. A smooth but steady increase in the muscle tension is produced by increasing the number of active motor units.

Back 667

C. A muscle is stimulated repeatedly for several seconds with a constant stimulus; the amount of tension produced then gradually increases to a maximum.The correct answer is C. During a muscle contraction, there is no mechanism to regulate the amount of tension produced in a given muscle protraction; therefore the muscle fiber is either producing tension or is in a relaxed state. This characteristic is known as the all-or-none principle. Therefore, the amount of tension produced by a skeletal muscle as a whole is determined by both the frequency of stimulation and the number of muscles stimulated. With these principles in mind, the following principles can be considered: Treppe is situation where a muscle is stimulated repeatedly for several seconds with a constant stimulus; the amount of tension produced then gradually increases to a maximum (choice C). When a muscle is producing peak tension during rapid cycles of contraction and relaxation relazation, it is known as tetanus. Complete tetanus occurs when a muscle is stimulated so frequently that the relaxation phase is completely eliminated (choice B). Wave summation occurs when a second stimulus arrives before the relaxation phase has ended and a second, more powerful, contraction occurs (choice D). Recruitment occurs when there is a smooth but steady increase in the muscle tension that is produced by increasing the number of active motor units (choice E). The muscle is producing peak tension during rapid cycles of contraction and relaxation.

Front 668

Within physiologic limits, activity of the respiratory center is decreased directly by1. decreased pH.2. increased pH.3. increased hemoglobin concentration.4. increased plasma carbon dioxide partial pressure.

Back 668

2. increased pH.The correct answer is choice 2. The respiratory center is located in the medulla. Increased C02 concentration in blood causes excess H2CO3 or carbonic acid formation which lowers pH near the respiratory center and increases ventilation. The opposite is true for decreased ventilation. Low C02 causes less acidity and higher pH, decreasing the activity of the respiratory center. Choice 3 is incorrect. The hemoglobin content of blood is fairly stable and does not change fast enough to be the controlling influence on the respiratory center. Choice 4 is incorrect. As mentioned previously, increased PC02 or partial pressure of carbon dioxide, will cause lower pH and will increase, not decrease, ventilation. So the correct answer to question is choice 2.

Front 669

A disturbance in cartilage formation in a fetus results in deformities of the1. sphenoid and zygomatic bones.2. axial skeleton and the base of the skull.3. axial skeleton and the flat bones of the skull.4. petrous portion of the temporal bones and the parietal bones.

Back 669

The correct answer is choice 2= AXIAL SKELETON AND THE BASE OF THE SKULL. Some bones in the human skeleton are formed by ossification of a cartilaginous model while others are not. When the bone is formed in a connective tissue other than cartilage, it is termed intramembranous ossification rather than cartilage ossification. Disturbance in cartilage formation will affect those bones produced on a cartilage model, but not those produced intramembranously. Let's check the choices. In general, the axial skeleton and skull base are ossified from cartilage models, so choice 2 is correct. Choice 3 is incorrect as most flat bones of the skull are intramembranous, not cartilaginous. Choice 4 is incorrect. The petrous portion of the temporal bone is from a cartilage model, while the squamous part is membranous. The parietal hones ossify intramembranously. Choice 1 is also incorrect. The sphenoid is mostly cartilaginous in ossification, but part of the greater wing is membranous. However, the zygomatic bone is intramembranous. So again the correct answer to question is choice 2.

Front 670

Tendons are comprised of which of the following types of collagenous connective tissue?A. AreolarB. ReticularC. Dense regularD. Dense irregular

Back 670

The correct answer is choice C, Dense regular. Tendons, as well as ligaments, fasciae and aponeuroses, are constructed of dense regular connective tissue. In this tissue, collagen fibers are arranged in a highly regular way. In tendons, the collagen fibers are parallel and resist pulling forces. Fibroblasts lie in rows between the collagen fiber rows. Dense irregular fibrous tissue is found in the dermis of skin and the capsules of many organs. The collagen fibers are thicker and are arranged in a more random pattern. Reticular connective tissue is composed of thin fibers and forms the framework for lymphoid organs and the stroma of the liver. Areolar connective tissue is another term for loose connective tissue, in which fibers are fewer, and matrix greater. So the correct answer to question is choice C

Front 671

The alveolar bone proper (cribriform plate) usually consists of1. woven bone.2. bundle bone only.3. lamellar bone only.4. bundle bone and lamellar bone.

Back 671

The correct answer is choice 4, bundle bone and lamellar bone... Let's review the choices. Woven bone is bone with a delicate framework of trabeculae, or cancellous bone. It contains many vascular spaces and is found in fetal bones when cartilage ossifies and in early repair of fractures. Choice 2, bundle bone, is a term which refers to bone adjacent to the periodontal ligament and contains Sharpey's fibers. It is not unique to the mandible, but is also found where muscles and ligaments attach to bone. Choice 3, lamellar bone, refers to concentric rings of bone laid down around central canals of haversian systems. This is known as compact bone. The correct choice is choice 4. The socket around the tooth, which is found in the alveolus of the mandible, contains both lamellar or compact bone and bundle bone with Sharpey's fibers of the periodontal ligament.

Front 672

The anterior interventricular (descending) artery is accompanied by the1. small cardiac vein.2. middle cardiac vein.3. great cardiac vein.4. coronary sinus.

Back 672

The correct answer is choice 3, the great cardiac vein... The anterior interventricular descending artery, a branch of the left coronary artery supplies blood to both the right and left ventricles. It follows the interventricular septum or sulcus to anastomose with the posterior interventricular branch of the right coronary artery. It is accompanied on this course by the great cardiac vein, choice 3. The small cardiac vein, choice 1, accompanies the marginal branch of the right coronary artery. The middle cardiac vein, choice 2, courses the heart with the posterior interventricular or descending artery. The coronary sinus, choice 4, receives most of the venous return from the epicardium and myocardium. Its tributaries include the great cardiac vein, the middle cardiac vein and the oblique vein. So the correct answer to question is choice 3.

Front 673

The apical cytoplasm of active serous glandular cells is typically filled with which of the following?A. Large amount of DNAB. Abundance of ribosomesC. Abundance of mitochondriaD. Abundance of lipid dropletsE. Abundance of zymogen granules

Back 673

The correct answer is choice E, zymogen granules... Let's use process of elimination here. Cytoplasm, in general, will not contain DNA, which is confined to the nucleus (and a small amount within mitochondria). Ribosomes produce protein, so large numbers of ribosomes should be found in cells secreting a lot of protein. Serous saliva is mostly water, salts, bicarbonate,and a small amount of amylase, so there is not much protein here. While the serous gland cells produce serous saliva, most of the work of adjusting its ionic content is acomplished by striated duct cells, which have a large number of energy-furnishing mitochondria. Large numbers of mitochondria are not found in the serous cells themselves. Lipid droplets will not be found because neither mucous nor serous saliva contains much lipid. Serous secretions are formed and secreted by way of zymogen granules, which are abundant at the cell base and then migrate to the secretory surface where their secretions are released. The correct answer to question is choice E.

Front 674

The area at which calcification of a tooth begins is the1. root.2. enamel matrix.3. cementoenamel junction.4. dentinoenamel junction

Back 674

The correct answer is choice 4, the dentoenamel junction... The calcification of a tooth begins at the dentinoenamel junction, choice 3. Maturation of the enamel is characterized by the gradual completion of mineralization. At each level, maturation begins at the dentinal end of individual enamel rods. The actual sequence of maturing rods, however, is from cusps down towards the cervical line. So. the correct answer to question is choice 4.

Front 675

A fracture of the hamulus affects the action of which of the following muscles?A. Superior constrictor of the pharynxB. Levator veli palatiniC. Tensor veli palatiniD. SalpingopharyngeusE. Buccinator

Back 675

TENSOR VELI PALATINIThe correct answer is choice C. The tendon of tensor veli palatini hooks around the pterygoid hamulus to insert into the palatal aponeurosis. Choice A is incorrect. The superior constrictor inserts into the pharyngeal tubercle of the occipital bone and the midline pharyngeal raphe. Choice B is incorrect. The levator veli palatini (levator palati) arises from the cartilaginous rim of the auditory tube and inserts directly into the palatal aponeurosis. It does not have contact with the hamulus. Choice D is incorrect. Salpingopharyngeus passes from the toms tubarius to the wall of the pharynx. Choice E is incorrect. Buccinator originates from the pterygomandibular raphe and inserts by blending with other muscles of facial expression around the corner of the mouth in an arrangement known as the modiolus.

Front 676

A major sensory innervation of the temporomandibular joint is derived from the1. great auricular nerve.2. auriculotemporal nerve.3. inferior alveolar nerve.4. temporal branches of the facial nerve.

Back 676

AURICULOTEMPORAL NERVEThe correct answer is choice 2. The temporomandibular joint is innervated by nerves from the auriculotemporal and masseteric branches of the mandibular nerve or V3. Choice 1, the greater auricular nerve, exits the spinal cord from levels C2 and C3 and innervates cutaneous areas of the neck, lower face and posterior head. Choice 3, the inferior alveolar, is a branch of the mandibular nerve or V3 which innervates the mandibular teeth, alveolar bone and gingiva. Choice 4, the temporal branches of the facial nerve, innervate the facial muscles above the palpebral fissure of the eye. So the correct answer to question 46 is choice 2.

Front 677

A patient who has damage to the right hypoglossal nerve will protrude the tongueA. upward.B. downward.C. straight forward.D. toward the right side.E. toward the left side.

Back 677

TOWARS THE RIGHTThe correct answer is choice D. If the muscles of the right side of the tongue are damaged, the effect of unopposed action of the muscles on the unaffected side will be to protrude the tongue across the midline. Hence the patient sticks out his tongue toward the side of the lesion. Choice A is incorrect. Contraction of genioglossus, the largest and most powerful of the tongue muscles, draws the root of the tongue forward and causes the tip to protrude. Choice B is incorrect. See (A) above. Choice C is incorrect. For the tongue to protrude straight forward, the genioglossi of both sides must be functional. Choice E is incorrect. In a case of unilateral damage to the hypoglossal nerve, the tongue protrudes to the same side as the lesion.

Front 678

A patient with absent direct and consensual light reflexes, but normal eyesight, is most likely to have a lesion on what cranial nerve?A. Abducens nerveB. Oculomotor nerveC. Optic nerveD. Trochlear nerveE. Trigeminal nerve

Back 678

OCULOMOTOR NERVEThe correct answer is B. The oculomotor nerve (choice B) functions to lift the upper eyelid, turn the eyeball upward, downward and medially, constricts the pupil and accommodates the eye. When this nerve is damaged both the direct and consensual light reflexes may be absent. In the direct reflex, the pupil will contract when a light is shone in the patient's eye. The consensual light reflex is seen when a light is shone in one eye and the observer notes the contraction of the pupil in the other eye. The abducent nerve (choice A) functions to turn the eyeball laterally. The optic nerve (choice C) is involved with vision and carries visual messages in nervous form to the brain for interpretation. The trochlear nerve (choice D) functions to turn the eyeball downward and laterally. The trigeminal nerve (choice E) is involved in the corneal reflex.

Front 679

A portion of which of the following muscles has fibers inserting into the articular disk of the temporomandibular joint?1. Upper head of the lateral pterygoid2. Lower head of the lateral pterygoid3. Deep head of the medial pterygoid4. Superficial head of the medial pterygoid

Back 679

UPPER HEAD OF THE LATERAL PTERYGOIDThe correct answer is choice 1. The only muscle which connects to the articular disk of the temporomandibular joint is the lateral or external pterygoid. The upper head of this muscle inserts through the fibrous capsule of the joint and into the articular disk. Choices 3 and 4 are incorrect. The medial or internal pterygoid is a jaw elevator or closing muscle. Both the superficial and deep head of the medial pterygoid insert on the medial surface of the mandible. The medial pterygoid closes (elevates) the mandible, and the lateral pterygoid acts in opening (depressing) and protruding. The primary retruding muscle is the temporalis (posterior fibers). Anyway, the correct answer to question is choice 1.

Front 680

A tumor of the maxillary sinus may cause an overflow of tears by exerting pressure on the1. lacrimal gland.2. lacrimal puncta.3. conjunctival sac.4. nasolacrimal duct.

Back 680

NASOLACRIMAL DUCTThe correct answer is choice 4. The maxillary sinus is the largest of the paranasal sinuses. It is pyramidal in shape and lies within the maxillary bone. Anteriorly, it extends to the nasolacrimal duct as a lacrimal recess. The tumor of the maxillary sinus may cause an overflow of tears when the tumor exerts pressure in the lacrimal duct, choice 4. The lacrimal duct functions as a drain into the nasal cavity and when a blockage occurs, tears cannot drain into the nose and therefore will run out onto the cheek. Lacrimal glands, choice 1 located in the superior and lateral region of the orbit, produce tears. The lacrimal puncta, choice 2, is an opening marking the beginning of the lacrimal canaliculus through which lacrimal fluid is transported to the lacrimal sac. Conjunctival sac, choice 3, is a space enclosed by the eyelid and it opens into the skin of the face at the palpebral fissure. So the correct answer to question is choice 4.

Front 681

cidophils (alpha cells) of the hypophysis secrete1. insulin.2. thyroxin.3. sex hormone.4. growth hormone.

Back 681

GROWTH HORMONEcidophils (alpha cells) of the hypophysis secrete1. insulin.2. thyroxin.3. sex hormone.4. growth hormone.

Front 682

All of the following structures are concerned with development of the tongue EXCEPT the1. copula.2. macula.3. tuberculum impar.4. second branchial arch.5. third branchial arch.

Back 682

MACULAThe correct answer is choice 2. Let's review the contribution of each choice. The first branchial arch produces an elevation known as the tuberculum impar, choice 3, which will form the anterior two-thirds of the tongue served by the mandibular nerve. The second arch, choice 4, contributes only the branch of its nerve, the chorda tympani of the facial nerve for taste sensation to the anterior two-thirds. The third branchial arch (choice 5) contributes to the hypobranchial eminence which, together with the copula (choice 1), give rise to the posterior one-thhd of the tongue. The macula, choice 2, is not involved in tongue formation. The macula can be found in the inner ear, in the retina and in the kidney, but it is not involved in tongue formation. So the correct answer to question is choice 2.

Front 683

All of the following structures can be seen in a histologic examination of the adult parotid gland EXCEPT1. striated ducts.2. serous demilunes.3. intercalated ducts.4. myoepithelial cells.5. granular serous cells.

Back 683

SEROUS DEMILUNESThe correct answer is choice 2. The parotid gland produces serous secretions. Granular serous cells, choice 5. produce the original secretion which travels through intercalated ducts (choice 3) to the striated ducts (choice 4). In the striated ducts ion exchange occurs and the final ionic concentrations of saliva arc cstahlishcd. Choice 4, myoepithelial cells are involved in contraction and movement of the saliva out of the acini, where the saliva is first produced. Choice 2. serous demilunes, are found in the submaxillary gland, a mixed mucous and serous gland. They produce serous secretions and surround mucous acini. Serous demilunes are absent in the parotid gland. The parotid is almost entirely serous. so dcmiluncs (which surround mucous acini) are not found there. So the correct answer to question is choice 2.

Front 684

An example of fibrous connective tissue of the reticular type would beA. AdiposeB. Bone marrowC. Capsules of organsD. Dermis of the skinE. Tendons

Back 684

BONE MARROWThe correct answer is B. Fibrous tissues are categorized according to their content of fibers. The two basic types of fibrous tissue are loose fibrous tissue and dense fibrous tissue. Loose fibrous tissue includes reticular tissues, such as bone marrow (choice B), lymph nodes and the spleen. Other forms of loose connective tissue include adipose tissue (choice A) and areolar tissue which is found in the capsules of organs (choice C). Dense fibrous tissue is subdivided into two types of tissue: unorganized dense fibrous tissue, such as the dermis of the skin, (choice D) and organized dense fibrous tissue, such as the tissue found in tendons (choice E).

Front 685

An individual who loses the ability to swallow food most likely has a lesion onA. Cranial nerve VIB. Cranial nerve VIIC. Cranial nerve VIIID. Cranial nerve IXE. Cranial nerve X

Back 685

CN IXThe correct answer is D. The glossopharyngeal nerve or cranial nerve IX (choice D) innervates the pharynx and posterior portion of the tongue. Therefore, if an individual loses their ability to swallow food, they most likely have a lesion on cranial nerve IX. Cranial nerve VI (choice A) is primarily responsible for eyeball movements and proprioception. Cranial nerve VII (choice B) innervates various facial muscles and the taste from the anterior portion of the tongue. Cranial nerve VIII (choice C) is involved with one's sense of hearing and equilibrium and cranial nerve X (choice E) or the Vagus nerve innervates various organs in the viscera.

Front 686

An organ with a retroperitoneal location that can be approached surgically without violating the continuity of the peritoneum is the1. ovary.2. kidney.3. spleen.4. gallbladder.

Back 686

KIDNEYThe correct answer is choice 2. Retroperitoneal structures such as the kidney are located dorsal to the dorsal peritoneum of the abdominal cavity. They lie on the ventral surface of the quadratus lumborum muscle just lateral to the psoas muscle and vertebral column. As such, they can be approached surgically from the dorsal side or back. Choice 1, the ovary, is not usually retroperitoneal and peritoneum would have to be cut in order to reach it. A retroperitoneal ovary is an abnormality. Similarly, neither the spleen nor gall bladder are retroperitoneal and are suspended by mesentery from the peritoneum. So the correct answer to question is choice 2.

Front 687

Apical abscesses on certain teeth have a marked tendency to produce cervical spread of infection that occurs most rapidly in abscesses of1. mandibular incisors.2. mandibular canines.3. maxillary premolars.4. mandibular second and third molars

Back 687

MANDIBULAR SECOND AND THIRD MOLARSThe correct answer is choice 4. This is something that you will tend to see clinically soon. Anyway certain apical abscesses have greater potential for spreading to the cervical or neck area than others. In particular, mandibular second and third molar infections may travel down fascial planes into the neck. Since three of these fascial planes form the visceral compartment which opens into the thorax, dental infections can on occasion even enter the superior mediastinum of the thorax. The superior mediastinum contains many crucial structures, including the aortic arch, the superior vena cava. the vagus and phrenic nerves, and many other structures. Of the other answer choices, note that maxillary teeth are not likely to lead to cervical fascial planes and that mandibular incisors and canines. being in the same general anatomic area, are not therefore likely to be the correct answers. Anyway, the correct answer to question is choice 4.

Front 688

As a result of a mandibular block injection, a patient has developed a paralysis of the muscles of facial expression. Where was the anesthetic solution most likely deposited?1. lnto the parotid gland2. Near the chorda tympani3. lnto the pterygoid plexus4. Through the mandibular notch

Back 688

INTO THE PAROTID GLANDThe correct answer is choice 1. All of the muscles of facial expression are innervated by the facial nerve. cranial nerve VII. It exits the skull via the stylomastoid foramen and passes anterolaterally through the parotid gland. It crosses superficial to the external carotid artery and the retromandibular vein. It breaks into a number of branches which emerge separately from the gland to supply the muscles of facial expression on their deep surfaces. Therefore, if paralysis were to develop as a result of a mandibular block injection, the anesthetic solution is probably deposited in the parotid gland, choice 1. The chorda tympani, choice 2, a branch of the facial nerve, cranial nerve VII, conveys taste sensation from the anterior two thirds of the tongue. The pterygoid plexus, choice 3, a network of veins, lies in close association with the lateral pterygoid muscle and the middle portion of the maxillary artery. It receives drainage from the veins of the nasal cavity, oral cavity and paranasal sinuses. Injection through the mandibular notch, choice 4, will not result in facial paralysis since it will already be past the major branches of the facial nerve. So the correct answer to question is choice 1.

Front 689

As a tooth undergoes attrition with age and with use, it maintains contact with its antagonist. Which of the following describes how this phenomenon occurs?1. The tooth forms additional apical dentin.2. There is continual apposition of bone at the fundus of the tooth socket.3. There is continual apposition of cementum in the tooth's apical region.4. None of these

Back 689

CONTINUAL APPOSITION OF CEMENTUM IN THE TOOTH'S APICAL REGION.The correct answer is choice 3. The wear of teeth by attrition with age is a physiologic and regular occurrence. Contact between teeth of opposing arches is kept by active eruption. This is achieved by compensatory deposition of cementum at the apical region of the root, choice 3. Choices 1 and 2 are incorrect because neither dentin nor bone is added in order to make the tooth erupt further. So the correct answer to question is choice 3.

Front 690

As demonstrated by the pattern of sensory innervation, which of the following branchial arches are concerned in development of the tongue?A. First and second onlyB. First, second, and thirdC. Second and third onlyD. Second, third, and fourthE. Third and fourth only

Back 690

FIRST SECOND AND THIRD* I BELIEVE 4TH IS ALSOThe correct answer is choice B. General sensation from the anterior two-thirds of the tongue is conveyed by the lingual branch of V3. CN V is the nerve of the first arch. Taste from the anterior two-thirds of the tongue is conveyed by chorda tympani, a branch of CN VII. CN VII is the nerve of the second arch. Both general sensation and taste from the posterior one-third of the tongue are conveyed by CN IX. CN IX is the nerve of the third arch. Choice A is incorrect. The first and second arches are concerned in development of the anterior two-thirds of the tongue. Choice C is incorrect. Branches of the nerves from arches II and III convey taste from different parts of the tongue. Choice D is incorrect. Branches of the nerves of arches II, III and IV convey taste from all parts of the tongue, but general sensation from the anterior two-thirds is not conveyed by any of these nerves. Choice E is incorrect. Branches of the nerves from arches III and IV convey sensory information from the posterior aspect of the tongue.

Front 691

As the subclavian vein crosses the first rib, it liesA. anterior to the anterior scalene muscle.B. posterior to the anterior scalene muscle.C. posterior to the posterior scalene muscle.D. between the anterior and the posterior scalene muscles.E. between the scalene posterior and the levator scapulae muscles.

Back 691

ANTERIOR TO THE ANTERIOR SCALENE MUSCLEThe correct answer is choice A. The subclavian vein passes anterior to the anterior scalene muscle in the root of the neck. Upon reaching the outer border of the first rib, it becomes the axillary artery. Choice B is incorrect. The subclavian artery and the brachial plexus pass posterior to scalenus anterior. Choice C is incorrect. The subclavian artery and the trunks of the brachial plexus emerge into the posterior triangle by passing between the anterior and middle scalene muscles. Choice D is incorrect. Choice E is incorrect.

Front 692

At a muscle-tendon junction, the union is made by1. myofibrils connecting with collagenous fibrils of the tendon.2. an abundance of reticular fibers in the area of the junction.3. a continuity of connective tissue sheaths of the muscle with those of the tendon.4. a special thickening of sarcoplasm that unites with collagenous fibrils of the tendon.

Back 692

A CONTINUITY OF CONNECTIVE TISSUE SHEATHS OF THE MUSCLE WITH THOSE OF THE TENDON.The correct answer is choice 3. When muscles attach to tendons, the connective tissue surrounding the muscle continues uninterrupted around the tendon. In the tendon, the collagen fibers unite at one end to the bone or other material that the tendon attaches to and at the other end to the sarcolemma of the muscle fiber. There is no direct connection of the muscle fiber to the collagen fiber. Therefore, choice 1 is incorrect. Choice 2 is also incorrect. Reticular fibers form the meshwork inside lymph nodes, which acts as a foundation for filtration of lymph, and reticular fibers are also found in the tunica media of arteries. Choice 4 is incorrect. Although the sarcolemma of the muscle attaches to the collagen fibers, the sarcoplasm or cytoplasm of the muscle fiber does not. So the correct answer to question is choice 3.

Front 693

Bacteria are frequently ingested by1. mast cells.2. fibrocytes.3. small lymphocytes.4. basophilic leukocytes.5. neutrophilic leukocytes.

Back 693

NEUTROPHILSThe correct answer is choice 5. Neutrophils or PMNs or polymorphonucleocytes actively ingest bacteria through the process of phagocytosis. Neutrophils are granulocyte-type white blood cells. Other granulocytes are eosinophils and basophils. Choice 4, basophils, contain heparin and histamine, but do not phagocytize bacteria. Choice 1, mast cells, are involved in the immune response and also contain heparin and histamine. They are found in large numbers in connective tissue. Choice 2, fibrocytes, produce connective tissue fibers. Choice 3, lymphocytes, are involved in immune response and serve a variety of defensive functions. Blymphocytes may become plasma cells and produce antibodies. T-lymphocytes may assist B-lymphocytes or may destroy foreign cells. Anyway, the correct answer to question is choice 5.

Front 694

Basket (myoepithelial) cells are located in the1. periodontal ligament.2. lumen of secretory acini.3. lamina propria of gingiva.4. lumen of intercalated ducts.5. spaces between the basal lamina and the secretory cell membrane.

Back 694

SPACES BETWEEN THE BASAL LAMINA AND THE SECRETORY CELL MEMBRANEThe correct answer is choice 5. Basket cells or myoepithelial cells can be found in the secretory portions of some exocrine glands. These cells function as the contractile elements of the gland and are located between the secretory cell membrane and the basal lamina, choice 5. So the correct answer to question is choice 5.

Front 695

The arterial supply of the submandibular gland is from which branch of the external carotid artery?1. Ascending pharyngeal2. Superior thyroid3. Maxillar4. Facial

Back 695

The correct answer is choice 4, the facial artery... The external carotid artery divides into multiple branches. Among the most important are the superior thyroid to the thyroid and surrounding tissue (choice 2); the lingual to the tongue; the facial to the pharynx, soft palate, tonsil. submandibular gland, upper lip and surrounding areas (correct choice 4); the ascending pharyngeal to the pharynx, palatine tonsil and auditory tube (choice 1); and the maxillary to the middle ear, skull. periosteum, mandible, teeth, chin, muscles of mastication, soft palate and maxillary sinus. among other areas (choice 3). So the correct answer to question is choice 4.

Front 696

The bony floor of the nasal cavity is formed by the1. palatine process of the maxilla and the vertical part of the palatine.2. palatine process of the temporal and the horizontal part of the palatine.3. vomer and the vertical part of the palatine.4. palatine process of the maxilla and the horizontal part of the palatine.

Back 696

The correct answer is choice 4, the palatine process of the maxilla and the horizontal part of the palatine. The bony floor of the nasal cavity is formed by two bones. The palatine bone is L-shaped with a horizontal and vertical plate. The horizontal plate has a smooth upper nasal surface and borders anteriorly on the palatine process of the maxilla. The two palatine processes of the maxilla fuse in the midline at the anterior nasal spine. So sections of the palatine and maxillary bones form the nasal floor. Choice 1 is incorrect because the horizontal, not vertical, process of the palatine is involved. Choice 2 is incorrect because the temporal bone is not involved in composing the floor of the nasal cavity. Choice 3 is incorrect. The vomer and vertical parts of the palatine bone are not involved in forming the floor of the nose. The vertical or perpendicular plate of the palatine forms part of the lateral wall of the nasal cavity, while the vomer forms part of the nasal septum. So the correct answer to question is choice 4.

Front 697

The branch of the ophthalmic artery that pierces the optic nerve is the1. supraorbital.2. anterior ciliary.3. anterior ethmoidal.4. central artery of the retina

Back 697

The correct answer is choice 4, the central artery of the retina... The ophthalmic artery, a branch of the internal carotid artery, has many tributaries. Its first branch, the central artery of the retina, choice 4, arises in the optic canal and runs with the sheath of the optic nerve. It pierces the nerve about half way along its intraorbitai course and runs in the center of the nerve to supply the retina. The supraorbital artery, choice 1, runs between the levator palpebrae superioris and the periosteum to the supraorbital foramen to supply the skin of the forehead and the anterior front of the scalp. The anterior ciliary artery, choice 2, pierces the sclera behind the corneal scleral junction to join the greater arterial circle of the iris. The anterior ethmoidal artery, choice 3, passes through the anterior ethmoidal foramen on its course to the tip of the nose to supply the frontal sinus, the nasal mucoperiosteum and the skin of the nose. So the correct answer to question is choice 4.

Front 698

The buccinator muscle is supplied by which of the following nerves?A. FacialB. LingualC. Spinal acessoryD. lnferior alveolarE. Buccal nerve of the trigeminal

Back 698

The correct answer is choice A, the facial nerve... The buccinator is a muscle of facial expression, derived from the second pharyngeal arch. It is supplied by CN VII, the nerve of the second arch. Choice B is incorrect. The lingual nerve is a sensory branch of V3. Choice C is I incorrect. The spinal accessory supplies sternocleidomastoid and trapezius. Choice D is incorrect. The inferior alveolar nerve is a branch of V3 which conveys sensory information from the mandibular teeth and gingiva. It has a motor branch, the mylohyoid neve, which supplies mylohyoid and anterior belly of digastric. Choice E is incorrect. The buccal branch of V3, or "long buccal" nerve is a sensory nerve which supplies the skin of the cheek and the buccal mucosa

Front 699

The calcified bodies sometimes found in the PDL are BEST described as which of the following?A. CementiclesB. DenticlesC. BoneD. Enamel pearlsE. Mineralized interstitial tissue

Back 699

The correct answer is choice A, cementicles... Cementicles are formed by cementoblasts, and are small isolated pieces of cementum found on x-ray, located in the PDL. Denticles are small isolated pieces of cementum, formed by odontoblasts and found on x-ray, located within the pulp. Isolated pieces of bone are not found unless broken off during surgical procedures. Enamel pearls are isolated pieces of enamel, formed by ameloblasts, located on or close to the tooth crown. The correct answer to question is choice A

Front 700

Calcium ions are sequestered byA. T-tubules.B. sarcoplasm.C. sarcosomes.D. myofibrils.E. sarcoplasmic reticulum.

Back 700

SACROPLASMIC RETICULUMThe correct answer is choice E. Sarcoplasmic reticulum is specialized endoplasmic reticulum found in muscle cells, which serves as a reservoir for calcium ions. These ions are released to begin muscle contraction. Myofibrils are the smallest units of contraction visible under the light microscope. Multiple myofibrils make up the myofiber, or muscle cell. The myofibril is composed of myofilaments of two types, actin and myosin. The cell membrane is called the sarcolemma, and the cytoplasm is the sarcoplasm. Sarcosomes are mitochondria of the muscle cell. T-tubules are invaginations of the sarcolemma, and carry stimulation from nerve cells into the sarcoplasmic reticulum, causing calcium ion release, and muscle contraction. So the correct answer to question is choice E.

Front 701

Cell bodies of primary sensory neurons of mechanoreceptors in the periodontal ligament are found in which of the following brainstem nuclei?1. Nucleus solitarius2. Reticular formation3. Descending nucleus of V4. Chief sensory nucleus of V5. Mesencephalic nucleus of V

Back 701

MESENCEPHALIC NUCLEUS OF VThe correct answer is choice 5. The periodontal ligament is the dense fibrous connective tissue which occupies the periodontal space between the root of the tooth and the bone. It consists of a stroma of fibers in a gel of ground substance containing cells, blood vessels and nerve. The periodontal ligament contains mechanoreceptors that may be involved in reflex jaw activity. These receptors are mediated by the trigeminal nerve, cranial nerve V, in association with the mesencephalic nucleus of cranial nerve V in the brainstem. This is choice 5. The nucleus solitarius, choice 1, receives input from the glossopharyngeal nerve, cranial nerve IX, to mediate the gag and carotid reflexes. Reticular formation, choice 2, is a general term used to describe those parts of the brainstem composed of scattered cells intermingling with nerve fibers. Descending nucleus of V, choice 3, and chief sensory nucleus of V, choice 4, are present to confuse the test taker as they are not valid anatomic nuclei. The three sensory nuclei of the trigeminal are the mesencephalic nucleus of V, the principal nucleus of V and the spinal nucleus of V. So the correct answer to question is choice 5.

Front 702

Cell bodies of proprioceptive fibers in V are located in theA. chief nucleus.B. spinal nucleus.C. semilunar ganglion.D. geniculate ganglion.E. mesencephalic nucleus.

Back 702

MESENCEPHALIC NUCLEUShe correct answer is choice E. The mesencephalic nucleus of CN V contains cell bodies of fibers concerned with proprioception. Choice A is incorrect. The chief nucleus of V contains cell bodies for fibers of the motor root of V3. Choice B is incorrect. The spinal nucleus of V contains second-order neurons in the pathway for pain and temperature. Choice C is incorrect. The semilunar ganglion contains sensory cell bodies for all three divisions of CN V. Choice D is incorrect. The geniculate ganglion a contains sensory cell bodies associated with CN VII.

Front 703

Cell bodies of taste fibers from the anterior two-thirds of the tongue are located in which of the following ganglia?1. Otic2. Geniculate3. Submandibular4. Pterygopalatine5. Trigeminal (semilunar)

Back 703

GENICULATEThe correct answer is choice 2. Taste from the anterior two-thirds of the tongue is supplied by the chorda tympani, a branch of the seventh nerve or the facial nerve. The cell bodies of these neurons are located in the geniculate ganglia. Choice 1 is incorrect. The otic ganglion contains cell bodies of the lesser superficial petrosal nerve of cranial nerve nine which is secretomotor to the parotid gland. Choice 3 is incorrect. The submandibular ganglion contains cell bodies from neurons of the chorda tympani which are secretomotor to the submandibular gland. Choice 4 is incorrect. The pterygopalatine ganglion contains cell bodies of neurons from the greater superficial petrosal nerve which is secretomotor to the lacrimal, nasal and palatine glands. Choice 5 is incorrect. The trigeminal ganglion contains cell bodies of neurons from the three branches of the uigeminal nerve, cranial nerve five. These do not I supply taste sensation to the anterior two-thirds of the tongue, although the mandibular branch does supply general afferent sensation to the anterior two-thirds. Anyway, the correct answer to question is choice 2.

Front 704

Cell bodies of the somatic motor system lie in which of the following locations?A. Dorsal hornB. Ventral hornC. Autonomic gangliaD. Dorsal root gangliaE. lntermediolateral horn

Back 704

VENTRAL HORNThe correct answer is choice B. Giant motor horn cells occupy the ventral horn in the gray matter of the spinal cord. Choice A is incorrect. The dorsal horn contains small central processes of sensory neurons and cell bodies and processes of synaptic cells (interneurons). Choice C is incorrect. Autonomic ganglia are collections of postsynaptic sympathetic or parasympathetic cell bodies. Choice D is incorrect. Dorsal root ganglia are collections of sensory cell bodies. Choice E is incorrect. The intermediolateral horn, or cell column, is a collection of preganglionic autonomic cell bodies.

Front 705

Cells of the stratum granulosum of thick stratified squamous epithelium characteristically contain1. melanin granules.2. keratin granules.3. keratohyalin granules.4. granules that are organelles.

Back 705

KERATOHYALIN GRANULESThe correct answer is choice 3. The stratum granulosum is a layer of epithelial cells. Let's review the layers briefly. The most undifferentiated basal layer is called the stratum basale. It consists of a single layer of columnar cells. Above this layer is the stratum spinosum or the prickle cell layer. These cells are more flattened and more differentiated than the stratum basale cells. Above the stratum spinosum is the stratum granulosum, flattened cells containing keratohyalin. The outermost layer of cells is the stratum corneum. These cells are dead, flat keratinized cells which flake off the skin or gingiva. So choice 3 is correct. Choice 2, keratin, is found in the stratum corneum. Choice 1, melanin, is found in melanocytes or dendritic cells. These are found in the deepest layer of the epidermis and have processes extending between various adjacent epidermal cells. Choice 4 is incorrect. The keratohyalin granules in the stratum granulosum cells are not organelles. So the correct answer to question is choice 3.

Front 706

Cementum differs from dentin in that cementumA. contains more inorganic material than dentin.B. is not formed following eruption of the tooth.C. can contain cells, whereas dentin contains cells as well as cell processes.D. is produced by cells of the periodontal ligament, but dentin is produced by pulp cells.E. contains some elastic fibers, whereas dentin contains only collagenous fibers.

Back 706

IS PRODUCED BY CELLS OF THE PDL, BUT DENTIN IS PRODUCED BY PULPS CELLS.The correct answer is choice D. Let's review the choices in order. Of the three hard tissues in tooth structure, enamel is most inorganic, followed by dentin, and then cementum. Cementum is histologically most similar to bone. Cementum forms from cementoblasts which become active slightly before, during and after the crown of the tooth has already erupted. Root formation is incomplete when crowns are completely formed and already erupted. Cementum may contain cells(cementocytes in cellular cementum) or not contain cells (acellular cementum). Dentin is considered to be noncellular, as only odontoblastic processes and not whole odontoblasts are found in dentin. Cementoblasts are formed originally in the periodontal ligament, from the dental sac, while odontoblasts form in the pulp (correct choice D). Elastic fibers are not found in any of the three tissues. The inorganic matrix of both dentin and cementum is primarily, but not wholly, collagen. The correct answer to question is choice D.

Front 707

Circular fibers are present in the1. free gingiva and encircle the tooth.2. free gingiva and encircle alveolar bone.3. attached gingiva and encircle alveolar bone.4. periodontal ligament and encircle the tooth.

Back 707

FREE GINGIVA AND ENCIRCLE THE TOOTHThe correct answer is choice 1. Circular fibers are composed of connective tissue and surround the teeth. These fibers are located in the free gingiva. They do not attach to or encircle the alveolar bone, and are not part of the periodontal ligament. So choices 2, 3 and 4 are all incorrect. Periodontal ligament fibers include the horizontal alveolar crest, oblique and apical fibers. In addition, transseptal periodontal fibers attach from the cementum of one tooth to the cementum of another adjacent tooth. Anyway, the correct answer to question is choice 1.

Front 708

Compared with intertubular dentin, peritubular dentin is characterized by which of the following?A. Greater stainabilityB. Higher quantity of fluidsC. Lesser content of inorganic saltsD. Greater content of inorganic saltsE. Greater content of large collagen fibers

Back 708

GREATER CONTENT OF INORGANIC SALTSThe correct answer is choice D. Peritubular dentin refers to dentin surrounding the odontoblastic process. Intertubular dentin is the remaining dentin found elsewhere. Peritubular dentin is more mineralized and therefore contains both less water and less organic material (collagen, mostly) and stains less darkly. The correct answer to question is choice D.

Front 709

Dentinal tubules are S-shaped in the crown of the tooth due to theA. incremental pattern.B. epithelial diaphragm.C. crowding of odontoblasts.D. formation of peritubular dentin.E. calcification pattern of maturing dentin.

Back 709

CROWDING OF ODONTOBLASTSThe correct answer is choice C. Remember that dentin is formed by odontoblasts lining the periphery of the dental pulp, and that as enamel depositon proceeds outward, dentin deposition proceeds inward. As the odontoblasts lay down more and more dentin and near the interior of the dental papilla, they become closer to each other. The curving pattern of the dentin is due to the decreasing amount of space available for the dentinal tubules as they get longer and more interior. A wavy S-shaped pattern results. The correct answer to question is choice C.

Front 710

The capacity of the tongue for forceful movement depends on striated muscle supplied by which of the following cranial nerves?A. VB. VIIC. IXD. XE. XII

Back 710

The correct answer is choice E, XII.... The hypoglossal nerve is the sole motor nerve of the tongue. Choice A is incorrect. CN V conveys general sensory information via its lingual branch from the anterior two-thirds of the tongue.Choice B is incorrect. CN VII conveys taste from the anterior two-thirds of the tongue via its chorda tympani branch. Choice C is incorrect. CN IX conveys general sensation and taste from the posterior one-third of the tongue.Choice D is incorrect. CN X conveys taste from the portion of the tongue which reflects onto the epiglottis.

Front 711

The cellular organelle that binds and releases calcium during relaxation and contraction of skeletal muscle is the1. nucleus.2. lysosome.3. mitochondrion.4. transverse tubule.5. sarcoplasmic reticulum.

Back 711

The correct answer is choice 5, the sarcoplasmic reticulum.... All skeletal muscles are under voluntary control and contract when a signal passes to them from their motor nerve. When activated by this electrical signal, skeletal muscle contraction is initiated by an increase in free calcium ion concentration released by the sarcoplasmic reticulum. When contraction is complete calcium ions are recaptured by the sarcoplasmic reticulum and stored until the next contractile signal is received. The nucleus, choice 1, is the largest organelle in the cell. It contains the majority of the genetic material and is also an essential part of protein synthesis. Lysosomes, choice 2, are membrane-bound organelles in which intracellular digestive enzymes are stored. The mitochondria, choice 3, can be thought of as the powerhouses of the cell. They generate energy by producing ATP in the presence of oxygen. The transverse tubules, choice 4, are found in skeletal muscles in which they carry the electrical signal for the activation of sarcoplasmic reticulum to release calcium to initiate contraction. So the correct answer to question is choice 5.

Front 712

The cerebellar cortex is characterized histologically by which of the following types of cells?1. Basket2. Purkinje3. Pyramidal4. Martinotti5. Horizontal

Back 712

The correct answer is choice 2, Purkinje cells.... Cerebellar cortex refers to the outer layers of the cerebellum which is responsible for coordination of muscular contraction and movement. In particular, Purkinje cells of the cerebellar cortex are efferent neurons. However, other inhibitory cells called outer and inner stellate cells or basket cells are also present in the cerebellum. So it appears that choice 1 is also correct. The Purkinje cells are localized in the middle layer of the cerebellar cortex, while the inner and outer stellate cells or basket cells are located in the outer or molecular level. Choice 3 is definitely incorrect. Pyramidal cells refer to the cells of I the cerebellar pyramid which is not on the outer cortex, but moF interior. Choice 4 is incorrect. Martinotti cells are neurons with ascending axon processes found in the polymorphic layer of the cerebral cortex. Choice 5 is incorrect. Horizontal cells are found in the retina and synapse with rods and cones. So the correct answer to question is choice 2.

Front 713

The common bile duct, the hepatic artery and the portal vein are found grouped in the1. mesocolon.2. lesser omentum.3. greater omentum.4. gastrosplenic ligament

Back 713

the answers to a different question were given. I believe it is the lesser omentum

Front 714

The common hepatic artery is a branch of the1. gastric artery.2. splenic artery.3. celiac artery (trunk).4. superior mesenteric artery.

Back 714

The correct answer is choice 3, the celiac artery.... The common hepatic artery arises from the celiac trunk and supplies the liver. The celiac trunk is a small branch off the aorta below the level of the diaphragm. It branches into the common hepatic artery which is correct choice 3, the left gastric (choice 1) and the splenic (choice 2). The superior mesenteric artery (choice 4) arises approximately one centimeter below the celiac trunk and supplies the midgut. The right gastric artery (choice 1) arises from the proper hepatic which is a branch of the common hepatic. So our correct answer to question is choice 3. The aorta leads to the celiac trunk which leads to the common hepatic artery.

Front 715

The component of bone tissue that gives bone tensile strength is the1. elastic fibers.2. calcified ground substance.3. interconnecting canaliculi.4. periosteal connective tissue.5. collagenous fibrils of matrix.

Back 715

The correct answer is choice 5, collagenous fibrils of matrix... Tensile strength in bone or cartilage is dependent primarily on the number of collagenous fibers present. Choice 1 is incorrect. Elastic fibers will add flexibility and elasticity, but not tensile strength. Choice 2 is incorrect. The calcified ground substance adds compressive strength, not tensile strength. Choice 3 is incorrect. The interconnecting canaliculi serve to interconnect the lacunae which contain osteocytes. They also connect the lacunae to the haversian canal which contains blood vessels. Choice 4 is incorrect. Periosteum covers the bone surface and contains bone-forming osteoblasts, but does not increase tensile strength. So the correct answer to question is choice 5.

Front 716

The connective tissue sheath that surrounds a muscle as a whole and is synonymous with the gross anatomic deep fascia is the1. epimysium.2. endomysium.3. perimysium.4. periosteum.5. perichondrium

Back 716

The correct answer is choice 1., epimysium.... The basic unit of skeletal muscle is the muscle cell or fiber. These are grouped together into elongated bundles or fasciculi. The fasciculi are in turn associated in various patterns to form the muscle as a whole. Three different types of connective tissue are found in skeletal muscle. The endomysium, choice 2, a delicate connective tissue surrounds the individual muscle fiber. The perimysium, choice 3, a loose collagenous connective tissue wraps around each fasciculus. The epimysium, choice 1, a dense connective tissue sheath encloses the entire muscle. Periosteum, choice 4, a dense fibrous connective tissue layer covers the external surface of bone. Perichondrium, choice 5, is a zone of condensed connective tissue near the periphery of mature cartilage. So the correct answer to question is choice 1.

Front 717

The core of a cilium is composed ofA. microvilli.B. microtubules.C. microfibrils.D. tonofilaments.E. microfilaments

Back 717

The correct answer is choice B, microtubules... The cilium, like the flagellum, has a regular structural arrangement of microtubules, which in cross-section appear in a "9+2" arrangement. Nine sets of paired microtubules surround 2 central single microtubules. Microvilli are extensions of intestinal absorptive cell membranes which increase surface area. Microfibrils may refer to muscle cell myofibrils, the smallest contractile units of muscle. These, in turn, are made up of myofilaments of actin or myosin. Tonofilaments are found connecting to desmosomes, which connect some types of epithelial cells. The correct answer to question is choice B.

Front 718

The crescents or demilunes of the mucous alveoli of the sublingual gland are composed of which of the following cells?A. MucousB. SerousC. NeuralD. StriatedE. Myoepithelial

Back 718

The correct choice is B, serous... No, your eyes are not deceiving you. The answer refers to the fact that mixed glands which are primarily mucous, contain some serous cells as well. The sublingual gland is a good example. The serous cells in this gland are located surrounding alveoli of mucous cells. The group of serous cells forms a crescent or demilune. Striated cells refer to duct epithelial cells which have a striped appearance due to large numbers of mitochondria near their base. Myoepithelial cells (basket cells) form the basal layer of ducts and have a contractile function. The correct answer to question is choice B.

Front 719

The dentist incises the mucous membrane of the floor of the mouth. This incision extends from the molar region to the sublingual caruncle (papilla). Which of the following structural groups will be exposed first?A. Sublingual gland, lingual nerves, and submandibular ductB. Hyoglossus and mylohyoid muscles, and hypoglossal nerveC. Lingual nerve, lingual artery, and anterior belly of the digastric muscleD. Lingual nerve, hypoglossal nerve, and submental branch of the facial arteryE. Anterior belly of the digastric muscle, mylohyoid nerve, and submental branch of the facial artery

Back 719

The correct answer is choice A, the sublingual gland, lingual nerve, and sublingual duct.....The sublingual gland, lingual nerve and submandibular duct lie immediately deep to the mucosa of the floor of the mouth. The duct of the submandibular gland crosses the lingual nerve twice, first deeply and then superficially, as it courses to its opening at the sublingual caruncle. Choice B is incorrect. The hypoglossal nerve passes deep to mylohyoid and superifical to hyoglossus as it leaves the anterior triangle to enter the floor of the mouth. Choice 2 is incorrect. The lingual artery enters the tongue by passing deep to hyoglossus. The anterior belly of digastric forms a boundary of the submental triangle, a subdivision of the anterior triangle of the neck. Choice D is incorrect. The submental artery is a branch of the facial artery which travels with the mylohyoid nerve to supply mylohyoid and anterior digastric.

Front 720

The diploid number of chromosomes is maintained in proliferating somatic cells by which of the following processes?A. MeiosisB. MitosisC. BuddingD. AmitosisE. Cytokinesis

Back 720

The correct answer is choice B, mitosis.... Mitosis is the division of somatic cells(non-gametes) into other somatic cells. The formation of gametes(sex cells) from somatic cells is called meiosis. In mitosis, chromosome number is conserved, for example in humans the number will remain at 46. In meiosis, or reduction division, the resulting cells will have half the normal chromosome number. In humans this is 23. Budding refers to a type of mitosis used for asexual reproduction by organisms such as yeast. While it is mitotic, it is different from normal mitosis as the cytoplasm is divided unequally, with the bud getting only a small portion. Amitosis means non-mitosis. Cytokinesis is the division of cytoplasm during mitosis. It follows the division of nuclear material. So the correct answer to question is choice B.

Front 721

The esophagus is subdivided into three portions on the basis of a transition in the1. submucosa.2. adventitia.3. mucosal layer.4. muscularis externa.

Back 721

The correct answer is choice 4, muscularis externa.... The esophagus is a muscular tube, 25cm or 10 inches in length, that conveys food rapidly from the pharynx to the stomach. The esophagus is subdivided into three portions based on its muscularis externa. In the upper third of the esophagus, both the inner and outer layers consist of striated muscles. In the second third, bundles of smooth muscles begin gradually to replace the striated muscle and in the lower third, only smooth muscle is found. The submucosa, choice 1, consists of collagenous and elastic fibers and does not vary throughout the length of the esophagus. The adventitia, choice 2, connects the outer surface of the esophagus with surrounding organs. This layer is made up of loose connective tissue which is also uniform throughout the length of the esophagus. The mucosal layer, choice 3, is also uniform throughout the esophagus. This is the lining layer of the esophagus. So the correct answer to question is choice 4.

Front 722

The external carotid artery contributes to the blood supply of the nasal cavity by way of the1. facial artery, the superior labial artery and angular arteries.2. lingual artery, the deep lingual artery and internal nasal arteries.3. occipital artery, the ascending palatine artery and posterior nasal arteries.4. maxillary artery, the sphenopalatine artery and posterior lateral nasal arteries.5. superficial temporal artery, the transverse facial artery and external nasal arteries.

Back 722

The correct answer is choice 4, the maxillary artery, the sphenopalatine artery and posterior lateral nasal arteries.... The external carotid artery, also discussed in another question, supplies the nasal cavity through a variety of branches. The maxillary artery supplies the nasal cavity through branches in the infraorbital, the greater palatine, the sphenopalatine and its branches, and the posterior lateral nasal. So choice 4 is incorrect. Choice 1 is incorrect. The facial artery leads to the superior labial which does supply part of the nasal area, but the angular artery supplies the medial angle of the eye. Choice 2 is incorrect. The lingual artery and deep lingual artery basically supply the tongue with no nasal branches. Choice 3 is incorrect. The occipital artery supplies the area of the base of the head and dorsal neck, or the occipital area. It has no nasal branches. Choice 5 is incorrect. The superficial temporal artery is a terminal branch of the external carotid to the temporal bone area of the head. It has no nasal branches. The transverse facial artery is a branch of the superficial temporal artery, another terminal branch of the external carotid. It also has no nasal branches. The external nasal arteries are branches of the facial artery. So the correct answer to question is choice 4.

Front 723

The foramen ovale is located in the1. interatrial septum of the adult.2. interatrial septum of embryo and fetus.3. interventricular septum of the adult.4. interventricular septum of embryo and fetus.

Back 723

The correct answer is choice 2, interatrial septum of embryo and fetus... Since the lungs and the fetus are not functioning, various shunts and special structures are present in the fetal circulation to receive oxygenated blood from the placenta. The foramen ovale, an opening between the right and left atrium allows blood from the right atrium to pass directly into the left atrium thereby bypassing the lungs. A similar lung bypass structure in the fetus is the ductus arteriorosis which connects the fetal aorta and the pulmonary artery. So. the correct answer to question is choice 2.

Front 724

The greater peritoneal sac communicates with the lesser peritoneal sac by means of the1. aortic hiatus.2. inguinal canal.3. epiploic foramen.4. lesser pelvic aperture.5. superior pelvic aperture

Back 724

The correct answer is choice 3, the epiploic foramen... The peritoneal cavity is divided into two sections: the greater sac and the omental bursa or lesser sac. The omental bursa or lesser sac is an hourglass-shaped area which lies behind the stomach,.the lesser omentum and the caudate lobe of the liver. The greater and lesser sac communicate through the epiploic foramen which is located behind the right border of the lesser omentum. Choice 1 is incorrect. The aortic hiatus or aortic opening in the diaphragm allows the aorta and thoracic duct to pass through the diaphragm. Choice 2 is incorrect. The inguinal canal is the passage in the abdominal wall which transmits the spermatic cord in the male and the round ligament of the uterus in the female, and the ilioinguinal nerve. Choice 4 and 5 are incorrect. The lesser pelvic aperture and superior pelvic aperture refer to spaces or areas within the bony pelvis. So the correct answer to question is choice 3.

Front 725

Desmosomes function by serving asA. a means for communication between cells.B. a means for attachment of adjacent cells.C. an outlet for secretory products of a cell.D. a bridge for continuity of cytoplasm between adjacent cells.E. a means by which tonofibrils can pass from one cell into another.

Back 725

A MEANS OF ATTACHMENT OF ADJACENT CELLS.The correct answer is choice B. Desmosomes attach adjacent cells to each other, and are known as macula adherens. Tonofilaments from the cytoplasm also terminate in thickened cell membrane located at the desmosome. A nexus, or gap junction, is a site of possible chemical or electrical communication between cells. (Choice A). Choice C is incorrect, as secretory products do not leave through a desmosome. Choice D is incorrect, as cytoplasm of each cell ends at the desmosome, and is distinct from the cytoplasm of adjacent cells. Choice E is incorrect. Tonofibrils from each cell anchor into thickened cell membrane of the same cell, anchoring the cells cytoskeleton. So the correct answer to question is choice B.

Front 726

During an intraoral injection to the mandibular foramen, the needle passes through the mucous membrane and the buccinator muscle. As it does so, the needle liesA. inferior to the mandibular lingula.B. superior to the auriculotemporal nerve.C. lateral to the neck of the mandible.D. lateral to the medial pterygoid muscle.E. lateral to the stylomandibular ligament.

Back 726

LATERAL TO THE MEDIAL PTERYGOID MUSCLEThe correct answer is choice D. The medial pterygoid inserts along the inferior portion of the ramus of the mandible. The mandibular foramen is located approximately at the center of the inner surface of the ramus. The inferior alveolar nerve passes lateral to the medial pterygoid as it enters the foramen. Choice A is incorrect. The opening to the mandibular foramen lies at the same level as the lingula. Choice B is incorrect. The auriculotemporal nerve passes posteriorly from the trunk of V3 as it leaves the infratemporal fossa. Choice C is incorrect. The needle approaches the mandibular ramus from its medial, not lateral, aspect. Choice E is incorrect. The stylomandibular ligament is a thickened band of deep cervical fascia which interconnects the angle of the mandible and the styloid process. It is not related to the mandibular foramen.

Front 727

During endochondral ossification of a long bone of an extremity, the function of hyaline cartilage is to1. increase strength of the developing bone.2. provide a region where bone can grow in length.3. provide undifferentiated cells that will become osteoblasts.4. form cores of trabeculae that compose most compact bone of the diaphysis.

Back 727

PROVIDE A REGION WHERE BONE CAN GROW IN LENGTHThe correct answer is choice 2. In endochondral ossification, the epiphyses or ends of the long bone have areas of actively growing hyalin cartilage. This cartilage produces new cells at the growing end and becomes calcified at the older, nongrowing end, and the calcified cartilage is then replaced by bone. The two ends of the long bone thus grow gradually away from each other. Bone width is increased by a different method in which periosteum lays down new concentric bone layers. The growth in length, due to replacement of cartilage by bone, is known as endochondral ossification. Choice 1 is incorrect. Cartilage is eventually replaced by bone. It does not add strength to it. Choice 3 is incorrect. Osteoblasts do not develop from undifferentiated cartilage cells. Instead, they develop from perichondrial chondrocytes which were present in the cartilage. These chondrocytes are not undifferentiated. Choice 4 is incorrect. The trabeculae are sections of bone formed by osteoblasts and are not formed from cartilage. So the correct answer to question is choice 2.

Front 728

During swallowing, muscular contraction results in movements that seal off the oropharynx from the nasopharynx. Which of the following muscles cause movements that result in a fold in the posterior wall of the pharynx?A. Levator veli palatiniB. Tensor veli palatiniC. PalatopharyngeusD. Musculus UvulaeE. Palatoglossus

Back 728

PALATOPHARYNGEUSThe correct answer is choice C. Palatopharyngeus is one of the three muscles which form the longitudinal muscle layer of the pharynx. The other two are stylopharyngeus and salpingopharyngeus. Choice A is incorrect. Levator veli palatini (levator palati) elevates the soft palate. Choice B is incorrect. Tensor veli palatini (tensor palati) tenses the soft palate. Choice D is incorrect. Musculus uvulae assists in closing the nasopharynx during swallowing. Choice E is incorrect. Palatoglossus elevates the back of the tongue.

Front 729

Each of the following cell types secretes the substance with which it is paired EXCEPT1. Sertoli's cells-testosterone.2. corpus luteum-progesterone.3. alpha cells of the pancreas-glucagon.4. chromaffin cells of the suprarenal-catecholamine.

Back 729

SERTOLI'S CELL-TESTOSTERONE.The correct answer is choice 1. Let's review the pairs which are correctly matched first. The corpus luteum, choice 1, in the ovary is formed after the rupture of the graafian follicle. It forms under the influence of luteinizing hormone or LH from the anterior pituitary and secretes progesterone which helps maintain the uterine lining. Choice 2, alpha cells of the pancreas, secrete glucagon, a hormone which raises blood sugar, and is the antagonist of insulin. Insulin is produced by beta cells of the pancreas. Choice 4, chromaffin cells of the suprarenal or adrenal gland produce catecholamines, epinephrine and norepinephrine. These catecholamines are produced by the suprarenal or adrenal medulla. Choice 1 is incorrectly paired and is our correct answer. Testosterone is produced by interstitial cells of the testes. but not by Sertoli cells. Sertoli cells are supporting cells which help nourish developing spermatids. So the correct answer to question is choice 1.

Front 730

Each of the following develops as an outpocketing of the gut tube EXCEPT one. Which one is this EXCEPTION?A. LungB. LiverC. SpleenD. PancreasE. Gallbladder

Back 730

SPLEENThe correct answer is choice C. The spleen forms from mesoderm within the layers of the dorsal mesogastrium. Choice A is incorrect. The lungs bud from the ventral aspect of the foregut as the respiratory diverticulum at the junction of pharynx and foregut. Choice B is incorrect. The liver forms as the hepatic diverticulum between the layers of the ventral mesogastrium at the junction of foregut and midgut. Choice D is incorrect. The pancreas arises form dorsal and ventral primordia derived from the gut tube. Choice E is incorrect. The gall bladder develops from an outpocketing of the hepatic diverticulum in the ventral mesogastrium.

Front 731

Each of the following embryologic structures is derived from the first branchial arch EXCEPT one. Which one is this EXCEPTION?A. Tuberculum imparB. Maxillary processC. Mandibular processD. Intermaxillary processE. Lateral lingual swelling

Back 731

INTERMAXILLARY PROCESSThe correct answer is choice D. The intermaxillary segment is derived from the fusion of the medial nasal processes, which develop from the frontonasal process. Choice A is incorrect. The tuberculum impar, which participates in the formation of the anterior two-thirds of the tongue, is derived from the first arch. Choice B is incorrect. The maxillary process is part of the first arch. Choice C is incorrect. The mandibular process is part of the first arch. Choice E is incorrect. The lateral lingual swelling is derived from the first arch.

Front 732

Each of the following enters the orbit by way of the superior orbital fissure EXCEPT one. Which one is this EXCEPTION?A. Abducens nerveB. Trochlear nerveC. Oculomotor nerveD. Ophthalmic arteryE. Ophthalmic division of the trigeminal nerve

Back 732

OPTHALMIC ARTERYThe correct answer is choice D. The ophthalmic artery, together with the optic nerve, enters the orbit by passing through the optic foramen. Choice A is incorrect. The abducens nerve enters the orbit through the superior orbital fissure. Choice B is incorrect. The trochlear nerve enters the orbit through the superior orbital fissure. Choice C is incorrect. The oculomotor nerve enters the orbit through the superior orbital fissure. Choice E is incorrect. The ophthalmic division of the trigeminal enters the orbit through the superior orbital fissure.

Front 733

Each of the following muscles receives motor innervation from the ansa cervicalis EXCEPT one. Which one is this EXCEPTION?A. OmohyoidB. ThyrohyoidC. GeniohyoidD. SternohyoidE. Sternothyroid

Back 733

THYROHYOID AND GENIOHYOIDThe correct answer is choice B and choice C. Geniohyoid is supplied by a branch of C1 which travels with CN XII (hypoglossal nerve) and also supplies thyrohyoid. Choice A, Omohyoid, is incorrect. Omohyoid has two bellies, both supplied by ansa cervicalis. Choice D, Sternohyoid, and choice E, Sternothyroid, are both incorrect. They are both innervated by ansa cervicalis, which is a junction of nerves from C1, C2, and C3.

Front 734

Each of the following structures is an opening into the pterygopalatine fossa EXCEPT one. Which one is this EXCEPTION?A. Facial canalB. Pterygoid canalC. Pharyngeal canalD. Sphenopalatine foramenE. Pterygomaxillary fissure

Back 734

FACIAL CANALThe correct answer is choice A. The facial canal opens to the middle cranial fossa as the hiatus of the facial canal. Choice B is incorrect. The pterygoid canal (Vidian canal) conveys the nerve of the same name to the pterygopalatine fossa. It begins in the anterior wall of foramen lacerum at the base of the skull, and passes through the body of the sphenoid bone. Choice C is incorrect. The pharyngeal canal passes from the roof of the nasopharynx to the pterygopalatine fossa. Choice D is incorrect. The sphenopalatine foramen is an opening in the medial wall of the pterygopalatine fossa. It communicates with the nasal cavity. Choice E is incorrect. The pterygomaxillary fissure leads from the infratemporal fossa to the pterygopalatine fossa.

Front 735

The ground substance of hyaline cartilage is basophilic because it contains1. phosphatases.2. polypeptides3. orthophosphoric esters.4. sulfated proteoglycans.

Back 735

answers were to a different question---- sulfated proteoglycans is correct."The ground substance is composed of a mixture of amorphous (non-formed) and fibrous (formed) components. The amorphous component predominantly contains proteoglycans. These consist of polysaccharide chains (glycosaminoglycans) such as keratan sulphate and chondroitin sulphate, which are covalently bound to a protein core. These core proteins are in turn non-covalently bound to a long filament of hyaluronic acid to form large proteoglycan aggregates (Figure 1⇓). Their principle function is to retain water, which is bound to the negatively charged glycosaminoglycans (GAGs), and represents 75% of the total volume of the ground substance. The formed component of the ground substance is composed of collagen fibres that constitute 50% of the dry weight of cartilage. The collagen fibres interact electrostatically with the GAGs to form a cross-linked matrix. The main type of collagen fibre in hyaline cartilage is type II collagen which consists of three alpha-1 (type II) chains [α1(II)]3. This differs from the more common type I collagen, which occurs in skin, tendons and bone, in that it contains higher levels of hydroxylysine and is thus more hydrophilic."

Front 736

The growth rate in the cartilage of the epiphyseal plate of a long bone is markedly retarded when there is a lack of hormone from which of the following?A. HypophysisB. AdrenalsC. TestesD. ParathyroidsE. Islets of Langerhans

Back 736

The correct answer is choice A, hypophysis....The hypohysis is the anterior pituitary, and is the source of GH(STH, growth hormone, somatotropic hormone). It stimulates long bone growth at the epiphyseal plate. The adrenal medulla secretes noradrenaline, while the adrenal cortex secretes glucocorticoids and mineralcorticoids (choice B). The testes secrete testosterone (choice C). The parathyroids secrete parathyroid hormone (PTH). The islets of Langerhans of the pancreas secrete insulin and glucagon (choice E). None of these hormones have a direct influence on bone growth at the epiphyseal plate. The correct answer to question is choice A.

Front 737

The hepatic veins drain blood from the liver into theA. inferior vena cava.B. superior vena cava.C. azygos vein.D. portal vein.E. superior mesenteric vein.

Back 737

The correct answer is choice A, the inferior vena cava... Two or three hepatic veins drain from the liver to the inferior vena cava as it passes through the diaphragm to enter the right atrium of the heart. Choice B is incorrect. The superior vena cava returns blood from the head, neck and upper limbs to the right atrium of the heart. Choice C is incorrect. The azygos system drains blood from the veins of the posterior abdominal wall and posterior thoracic wall to the superior vena cava. Choice D is incorrect. The portal vein transports blood from the GI system and spleen to the liver. Choice E is incorrect. The superior mesenteric vein is a major tributary of the portal vein, which transports blood from the GI system and spleen to the liver.

Front 738

The hypophysis is situated in a fossa of which of the following bones?A. EthmoidB. FrontalC. TemporalD. SphenoidE. Palatine

Back 738

The correct answer is choice D, sphenoid... The hypophysis rests in a depression in the body of the sphenoid bone known as the hypophyseal fossa. The body of the sphenoid bone is also known as the sella turcica. It forms the midportion of the middle cranial fossa. Choice A is incorrect. The ethmoid bone contributes to the floor of the anterior cranial fossa, in the form of the crista galli and cribriform plate. Choice B is incorrect. The orbital plate of the frontal bone forms much of the floor of the anterior cranial fossa. Choice C is incorrect. The petrous portion of the temporal bone forms the postero-lateral aspect of the middle cranial fossa. Choice E is incorrect. The palatine bone does not contribute to the floor of the cranial cavity.

Front 739

The impulse-conducting mechanism in the heart is composed of1. autonomic nerve fibers.2. bundles of collagenous fibers.3. reticuloendothelial components.4. modified cardiac muscle fibers.

Back 739

The correct answer is choice 4, modified cardiac muscle fibers.... The conducting tissue of the heart or Purkinje fibers are specialized cardiac musclc cells which spread out throughout the heart and speed conduction. They are structurally different on the cellular level from normal contracting cardiac muscle fibers. Choice 1 is incorrect. Autonomic nerve fibers may control the heart rate through sympathetic and parasympathetic stimulation; however, they do not conduct the contraction impulse. Choice 2 is incorrect as collagenous fibers would be unlikely to have impulse-conducting abilities. Choice 3 is incorrect. Reticuloendothelial components refers to the tissue macrophage system and are part of the immune system. So the correct answer to question is choice 4.

Front 740

The infrahyoid muscles receive their motor innervation from which of the following?A. Vagus nerveB. Supraclavicular nervesC. Brachial plexusD. Pharyngeal plexusE. Branches of the cervical plexus

Back 740

The correct answer is choice E, branches of the cervical plexus.... The infrahyoid (strap) muscles receive their innervation from ansa cervicalis, with the exception of thyrohyoid, which is supplied by a branch of cervical nerve I which also supplies geniohyoid. Choice A is incorrect. The vagus supplies muscles of the pharynx and larynx. It does not supply the infrahyoid muscles. Choice B is incorrect. Supraclavicular nerves are cutaneous branches of cervical plexus derived from c3 and c4. They form three sets of branches (medial, intermediate, lateral) which supply the skin over the clavicle. Choice C is incorrect. The brachial plexus is derived from the lower four cervical nerves and the first thoracic nerve. It supplies muscles of the shoulder and axillary regions, and of the upper limb. Choice D is incorrect. Pharyngeal plexus consists of pharyngeal branches of CN's IX, X and the cranial poriton of XI. It supplies muscles of the pharynx and - soft palate.

Front 741

The jugular foramen transmits which cranial nerves?1. VII, IX, and XII2. IX, X, and XI3. IX, XI, and XII4. X, XI, and XII

Back 741

The correct answer is choice 2, IX, X, and XI... The jugular foramen is an irregular foramen situated lateral to the occipital condyle. It transmits the internal jugular vein, the glossopharyngeal nerve (cranial nerve IX), the vagus nerve (cranial nerve X) and the spinal accessory nerve (cranial nerve XI). So the correct answer to question is choice 2. Note that the questions of this nature are very straightforward and appear often on the boards. Review all the major foramina of the skull and the structures that pass through them in your review notes

Front 742

The junction between primary and secondary dentin is characterized by a1. resting line.2. reversal line.3. sharp reduction in number of dentinal tubules.4. sharp change in direction of dentinal tubules.5. Both 1 and 3 above

Back 742

The correct answer is choice 4, sharp change in direction of the dentinal tubules... Secondary dentin can be found just interior to primary dentin, narrowing and enclosing the pulpal tissue. When primary dentin borders on secondary dentin, the tubules abruptly change direction although their number is approximately the same. So choice 3 is incorrect. Choices 1 and 2 are also incorrect. Resting lines and reversal lines are lines present in bone remodeling and not in primary and secondary dentin. Reversal lines show where resorption ends and deposition begins and are scalloped. Arrest lines are highly calcified straight lines between layers of bone. Both types of lines are highly basophilic. So the correct answer to question is choice 4.

Front 743

The lamina papyracea is located in the orbital1. roof.2. floor.3. lateral wall.4. medial wall

Back 743

The correct answer is choice 4, medial wall.... The orbit consists of a roof, floor, medial and lateral walls. The roof is formed primarily by the orbital part of the frontal bone and also by the lesser wing of the sphenoid, The lateral wall is formed by the greater wing of the sphenoid, the zygomatic and the frontal bone. The medial wall is formed primarily by the frontal process of the maxilla, the maxillary process of the frontal bone, the small thin lacrimal bone, and the ethmoid bone. A thin section of the ethmoid bone, about the thickness of a sheet of paper, is known as the lamina papyracea. So the correct answer is choice 4. The only other choice we haven't mentioned is choice 2, the floor of the orbit, and that is formed by the orbital surface of the maxilla, the zygomatic bone, and the orbital process of the palatine bone.

Front 744

The large ascending bundle of fibers in the medulla that is composed of second order neuron fibers conveying proprioception and discriminatory touch sensations to conscious levels is the1. medial lemniscus.2. reticular formation.3. spinal trigeminal tract.4. inferior cerebellar peduncle.

Back 744

The correct answer is choice 1, medial lemniscus..... The medial lemniscus is an ascending fiber tract in the medulla and carries proprioceptive and touch sensation. Choice 2 is incorrect. The reticular formation is also in the medulla and contains both afferent and efferent fibers. Many of them connect to areas of the cerebellum, thalamus, corpus striatum and cerebral cortex. Choice 3 is incorrect. The spinal trigeminal tract is located in the lateral aspect of the medulla and carries painful and thermal sensations. Choice 4 is also incorrect. The inferior cerebellar peduncle connects the cerebellum to the medulla, and carries proprioceptive information back and forth from the cerebellum to the medulla. It does not reach the conscious levels of the cerebrum. So the correct answer to question is choice 1.

Front 745

The large mass of gray matter that bulges into the floor and the lateral aspect of the lateral ventricle is the1. hypothalamus.2. caudate nucleus.3. substantia nigra.4. amygdaloid complex

Back 745

The correct answer is choice 2, caudate nucleus.... The caudate nucleus is a comma-shaped section of the cerebrum and is located just inferiorly and laterally to the lateral ventricle of the brain. The hypothalamus, choice 1, is located far inferior to this area, below the thalamus and third ventricle. Among other functions, the hypothalamus produces hormone-releasing factors and controls temperature, hunger and thirst and other basic functions. Choice 3, the substantia nigra, is a large nucleus deep in the base of the cerebrum below the thalamus and too inferior to be the correct answer. Reduced dopamine production in the substantia nigra is associated with Parkinson's disease. Choice 4 is also incorrect. The amygdaloid complex is located within the tail of the caudate nucleus. Its function is not clearly known and it is located near the anterior portion of the lateral ventricle. So the correct answer to question is choice 2.

Front 746

The lateral boundary of the retropharyngeal space at the level of the oropharynx is the1. carotid sheath.2. pterygomandibular raphe.3. medial pterygoid muscle and its fascia.4. stylopharyngeus muscle and its fascia

Back 746

The correct answer is choice 1, carotid sheath.... The retropharyngeal space is an area anterior to the cervical vertebrae and composed of loose areolar tissue. It is bordered laterally by the carotid sheath with the contained vessels, including the carotid artery, internal jugular vein and vagus nerve. Choice 2, the pterygomandibular raphe, is a fibrous line to which the buccinator and superior constrictor of the pharynx attach. Choices 3 and 4 are incorrect. The medial pterygoid is a primary closing or elevating muscle which attaches to the mandible, the pterygoid plate and the palatine bone. The stylopharyngeus attaches to the styloid process, the wall of the pharynx and the thyroid cartilage. So anyway, the correct answer to question is choice 1.

Front 747

The lateral pterygoid muscle inserts into which of the following?A. Condylar process onlyB. Medial aspect of the mandibular ramusC. Articular disk of the temporomandibular joint onlyD. Articular disk of the temporomandibular joint and neck of the mandibleE. Articular disk of the temporomandibular joint and coronoid process

Back 747

The correct answer is choice D, articular disk of the TMJ and neck of the mandible..... Most of the fibers of lateral pterygoid insert into the fovea, a pit-like depression on the neck of the mandible. In most individuals, some fibers insert directly into the disk as well. Choice A is incorrect. Fibers of the lateral pterygoid insert specifically into the fovea of the neck of the mandible, and the articular disk (meniscus), which is not part of the condylar process. Choice B is incorrect. The medial pterygoid inserts along the medial aspect of the mandibular ramus. Choice C is incorrect. The majority of fibers of the lateral pterygoid do not insert into the disk. Choice E is incorrect. The temporalis inserts on the coronoid process of the mandible.

Front 748

The left recurrent laryngeal nerve is closely related at its beginning to theA. left subclavian artery.B. arch of the aorta and the left pulmonary veins.C. ligamentum arteriosum and the arch of the aorta.D. pulmonary trunk and the left brachiocephalic vein.E. ligamentum arteriosum and the left brachiocephalic vein.

Back 748

The correct answer is choice C, ligamentum arteriosum and the arch of the aorta.... The left recurrent laryngeal nerve recurs in the mediastinum, around the ligamentum arteriosum and arch of the aorta. Choice A is incorrect. The left recurrent laryngeal nerve is not associated with the left subclavian artery. The right recurrent laryngeal nerve, however, recurs around the right subclavian artery in the root of the neck. Choice B is incorrect. The recurrent laryngeal nerves do not contact the pulmonary veins. Choice D is incorrect. The recurrent laryngeal nerves ascend to the larynx by travelling between the trachea and esophagus, and do not contact the pulomonary trunk or brachiocephalic veins. Choice E is incorrect. The left recurrent laryngeal nerve does not contact the left brachiocephalic vein.

Front 749

The lingula of the mandible serves as an attachment for which of the following?A. TemporalisB. Stylomandibular ligamentC. Sphenomandibular ligamentD. Temporomandibular ligamentE. Tendon of the digastric muscle

Back 749

The correct answer is choice C, the sphenomandibular ligament.... The sphenomandibular ligament extends from the spine of the sphenoid bone to the lingula of the mandible. Choice A is incorrect. The temporalis inserts on the coronoid process of the mandible. Choice B is incorrect. The stylomandibular ligament extends from the angle of the mandible to the styloid process. Choice D is incorrect. The temporomandibular ligament attaches to the neck of the mandible. Choice E is incorrect. The intermediate tendon of the digastric muscle attaches to the hyoid bone.

Front 750

Each of the following structures is bound by a membrane EXCEPT one. Which one is this EXCEPTION?A. NucleolusB. LysosomeC. NucleusD. MitochondrionE. Pinocytotic vesicle

Back 750

NUCLEOLUSThe correct answer is choice A. The nucleolus is a darkly staining section of the nucleus, rich in RNA, in particular ribosomal RNA. It is not separated from the rest of the nucleus by a membrane. The lysosome is a single layer membrane-enclosed organelle containing various hydrolytic enzymes. The nucleus is separated from the cytoplasm by a double membrane, with many pores, known as the nuclear membrane. The mitochondrion, site of ATP synthesis, is also enclosed by a double layered membrane. Pinocytotic vessicles are formed as the plasma membrane(cell membrane) encloses material surrounding the cell and forms a vacuole (pinocytotic vessicle) around it. It is therefore surrounded by a single layered membrane. The correct answer to question is choice A.

Front 751

Each of the following structures lies between the hyoglossus and the mylohyoid muscles EXCEPT one. Which one is this EXCEPTION?A. Lingual nerveB. Lingual arteryC. Sublingual glandD. Submandibular ductE. Hypoglossal nerve

Back 751

LINGUAL ARTERYThe correct answer is choice B. The lingual artery passes deep to both mylohyoid and hyoglossus to enter the tongue. Choice A is incorrect. The lingual nerve enters the floor of the mouth between mylohyoid and hyoglossus to lie superficially under the mucosa. Choice C is incorrect. The sublingual gland lies immediately under the mucosa of the floor of the mouth. Choice D is incorrect. The submandibular duct crosses the lingual nerve twice as it passes toward the sublingual caruncle at the anterior aspect of I the sublingual gland. Choice E is incorrect. The hypoglossal nerve passes between mylohyoid and hyoglossus as it leaves the anterior triangle to enter the tongue.

Front 752

Enamel spindles are formed by1. cracks.2. ameloblasts.3. hypoplastic rods.4. hypocalcified rods.

Back 752

HYPOPLASTIC RODSThe correct answer is choice 3. Enamel spindles are formed from odontoblastic processes which project into the enamel and probably originally projected into the ameloblast layer. They are at right angles to the DEJ and may be responsible for sensitivity shown by patients as excavation nears the DEJ. Choice 1 is incorrect. Enamel lamellae, which are not related to spindles, appear to be naturally occurring cracks or cleavages in enamel. Choice 2 is incorrect. Ameloblasts form enamel and move away from the area of the DEJ as enamel is formed. Choices 4 and 5 are incorrect as enamel spindles are not related to enamel rods which are the mineralized structural components of enamel. So the correct answer to question is choice 3.

Front 753

Enlargement of the third ventricle and both lateral ventricles is caused by obstruction of theA. cerebral aqueduct.B. foramen of Magendie.C. foramina of Luschka.D. interventricular foramina of Monro.

Back 753

CEREBRAL AQUEDUCTThe correct answer is choice A. Obstruction of the cerebral aqueduct is the only blockage that will affect the lateral and third ventricles exclusively. Choice B is incorrect. Obstruction of the foramen of Magendie, in the roof of the fourth ventricle, will cause enlargement of the fourth ventricle as well as the other three. Choice C is incorrect. Obstruction of the foramina of Luschka in the fourth ventricle will cause enlargement of the entire ventricular system. Choice D is incorrect. Obstruction of the interventricular a foramina will cause enlargement of only the lateral ventricles.

Front 754

Fordyce spots appearing on the mucous membrane of the cheek result from the presence of1. aberrant sweat glands.2. aberrant sebaceous glands.3. superficial salivary glands.4. aberrant fatty accumulations.5. none of these.

Back 754

ABERRANT SEBACEOUS GLANDSThe correct answer is choice 2. Fordyce spots manifest most frequently as small yellow spots in a bilaterally symmetrical pattern on the cheek mucosa. Fordyce spots are considered a developmental anomaly. They are characterized by heterotopic collections of sebaceous glands at various sites in the oral cavity. It has been postulated that the occurrence of sebaceous glands in the mouth may result from inclusion of ectoderm having potentialities of skin during embryonic development of the maxillary and mandibular processes. The remaining choices do not describe origins of Fordyce spots. So the correct answer to question is choice 2.

Front 755

From an anatomic standpoint, an emergency airway may be established most readily by opening into the trachea1. between thyroid cartilages.2. at the level of the jugular notch.3. through the thyrohyoid membrane.4. through the median cricothyroid ligament.

Back 755

THROUGH THE MEDIAN CRICOTHYROID LIGAMENTThe correct answer is choice 4. The preferred location of an emergency airway is between the thyroid cartilage and cricoid cartilage in a ligamentous area known as the cricothyroid ligament. It is easier to pass an instrument through this connective tissue than through nearby hard tissue areas. Choice 1 is incorrect. The two thyroid cartilages are fused in the anterior midline. Choice 2 is incorrect. Jugular notches exist in the temporal and occipital bones and in the sternum. How they relate to this question is unclear. Choice 3 is incorrect. The thyrohyoid membrane runs from the hyoid bone to the thyroid cartilage. This area lies above the thyroid cartilage and is not used as an area for establishing airways. So the correct answer to question is choice 4.

Front 756

From which of the following is the periodontal ligament derived?A. Dental sacB. Enamel organC. Dental papillaD. Epithelial root sheathE. Outer enamel epithelium

Back 756

DENTAL SACThe correct answer is choice A. Briefly, the dental sac forms the periodontal ligament and, indirectly, the cementum, while the enamel organ produces, of course, enamel. The dental papilla produces pulp, and indirectly, the dentin. The epithelial root sheath forms the outline of the root, and induces the odontoblasts of the root to lay down the first layer of root dentin. Outside of this layer, it forms the periodontal ligament and from there cementoblasts will form the cementum of the tooth. The outer enamel epithelium, with the inner enamel epithelium and stellate reticulum form the enamel organ. The correct answer to question is choice A.

Front 757

Gingiva is different from alveolar mucosa in that gingiva has1. elastic fibers.2. simple epithelium.3. muscularis mucosa.4. stratified epithelium.5. high connective tissue papillae.

Back 757

HIGH CONNECTIVE TISSUE PAPILLAEThe correct answer is choice 5. Let's review the choices. Gingiva differs from alveolar mucosa in the types of fibers present. Gingiva contains collagenous fibers only, while alveolar or lining mucosa contains both collagenous and elastic fibers. So choice 1 is opposite and incorrect. Alveolar mucosa and gingiva do not differ in this way because both gingiva and alveolar mucosa are stratified epithelium, not simple. Choice 3 is incorrect. The submucosa of gingival tissue contains many collagen fibers, but not muscle or elastic fibers, while the submucosa of alveolar or lining mucosa contains collagenous, elastic and muscle fibers. So choice 3 is opposite and incorrect. Choice 5 is correct. Connective tissue papillae extend into the gingiva to a much greater degree than they do into the alveolar mucosa. Rete pegs which are epithelial extensions into the submucosal tissue are also more prominent in gingival tissue than in alveolar mucosa. So the correct answer to question is choice 5.

Front 758

Hertwig's epithelial root sheath is derived from which of the following?A. Inner dental epithelium and stellate reticulumB. Inner dental epithelium and stratum intermediumC. Outer dental epithelium and stellate reticulumD. Outer dental epithelium and stratum intermediumE. Inner dental epithelium and outer dental epithelium

Back 758

INNER AND OUT DENTAL EPITHELIUMThe correct answer is choice E. At the cervical end of the crown, the inner and outer enamel epithelia come together and the stellate reticulum is lost. The joined layers are now called the epithelial root sheath of Hertwig. It induces the tissue nearby to form odontoblasts for root dentin, which in turn induces exterior cells nearby to form into cementoblasts, and produce cementum. Note that the stratum intermedium is a thin layer of cells between the inner enamel epithelium and the stellate reticulum. Its function is unclear. The correct answer to question is choice E.

Front 759

Highly skilled, discrete motor activity of the hand is dependent on which of the following cortical areas of the hemisphere?A. Transverse temporal gyrusB. Angular gyrus of the parietal lobeC. Precentral gyrus of the frontal lobeD. Paracentral lobule on the medial surface

Back 759

PRECENTRAL GYRUS OF THE FRONTAL LOBEThe correct answer is choice C. The precentral gyrus of the frontal lobe is the "motor strip" from which voluntary motor activity originates. Choice A is incorrect. The transverse temporal gyrus is an auditory area. Choice B is incorrect. The angular gyrus of the parietal lobe is a sensory language area in the dominant hemisphere. Choice D is incorrect. The paracentral lobule is the portion of the motor strip which reflects onto the medial surface of the frontal lobe. It is concerned with movement of the distal lower extremity.

Front 760

Histologically, the osteoclasts of bone resorption are typicallyA. anuclearB. mononuclear.C. multinuclear.D. polymorphonuclear

Back 760

MULTINUCLEARThe correct answer is choice C. Osteoclasts are bone resorbing cells which are are involved in calcium equillibrium, bone remodeling, and bone maintenance. They are stimulated by parathyroid hormone. They have an unusual appearance, with many nuclei (multinuclear). Anuclear, choice A, refers to lack of a nucleus(ex:erythrocyte). Mononuclear, choice B, refers to one nucleus (most cells). Polymorphonuclear, choice D, refers to cells of the same type having nuclei of various shapes, but only one per cell.(ex: neutrophils or polymorphonucleocytes). The correct answer to question is choice C.

Front 761

How many lobes does the right lung usually have?A. 1B. 2C. 3D. 4E. 5

Back 761

3The correct answer is choice C. The right lung has three lobes: superior, middle, and inferior. Choice A is incorrect. Choice B is incorrect. The left lung has two lobes: superior and inferior. Choice D is incorrect. Choice E is incorrect.

Front 762

Hyaline cartilage differs from bone in that hyaline cartilage1. cells lie in lacunae.2. may grow interstitially.3. may grow appositionally.4. can become more highly calcified.

Back 762

MAY GROW INTERSTITIALLYThe correct answer is choice 2. Hyalin cartilage is a support tissue which may later be replaced by bone or may persist throughout life. In cartilage, cells called chondrocytes are found in spaces called lacunae. However, this does not differ from bone where osteocytes can also be found in lacunae, so choice 1 is incorrect. Choice 2 is our correct answer. Cartilage may grow interstitially, which means growth from within the interior of the tissue up to a certain size beyond which the chondrocytes will die, being too far from vascular supply. Bone cannot grow interstitially as osteocytes are locked into their calcified lacunae. Bones grow at their ends rather than throughout their interior. This growth at the ends is known as appositional growth. So while cartilage can undergo both types of growth. bone can only grow appositionally. Choice 3 is therefore incorrect as they both can grow appositionally. Choice 4 is incorrect. Hyaline cartilage generally does not calcify and become bone. Rather, it calcifies and is replaced by bone in a process known as ossification. However, cartilage does not ever become more highly calcified than bone. So the correct answer to question is choice 2.

Front 763

If the facial nerve were to be cut just after it exited the stylomastoid foramen, it would cause loss of innervation to which of the following?A. Lacrimal glandB. Mylohyoid muscleC. Submandibular glandD. Oribicularis oculi muscleE. Anterior belly of the digastric muscle

Back 763

ORIBICULARIS OCULI The correct answer is choice D. The motor root of the facial nerve enters the parotid gland, where it branches to supply the muscles of facial expression. Choice A is incorrect. The branch of CN VII which supplies the lacrimal gland is the greater superficial petrosal nerve. It is given off inside the petrous portion of the temporal bone, where it runs in the facial canal. Choice B is incorrect. The nerve to mylohyoid is a branch of the inferior alveolar nerve, a branch of CN V3. Choice C is incorrect. The parasympathetic fibers to the submandibular ganglion and gland travel in the chorda tympani, a branch of CN VII which leaves the motor root in the middle ear cavity. Choice E is incorrect. Anterior belly of digastric is supplied by the branch of CN V3 which innervates mylohyoid.

Front 764

If the spinal tract of the fifth cranial nerve were sectioned at the level of the caudal medulla, which of the following modalities would be most affected?1. Taste2. Proprioception3. Pain from the ipsilateral side of the face4. Light touch from the contralateral side of the face

Back 764

PAIN FROM IPSILATERAL SIDE OF THE FACEThe correct answer is choice 3. The fifth cranial nerve or trigeminal nerve has many functions, including motor, sensory and parasympathetic. It is sensory to all areas of the face through its branches: the ophthalmic V1, the maxillary V2, and the mandibular V3. Sensation is carried to the ipsilateral or same side of the brain as the sensation is received on. Choice 4 is therefore incorrect. The trigeminal nerve would be the afferent nerve for light touch, but the sensations do not cross to the contralateral side of the brain. B Choice 2 is incorrect. Some proprioception from the TMJ and muscles of mastication is related to the trigeminal nerve, but other proprioceptive information from the facial muscles is transmitted by the facial nerve, cranial nerve 7. Choice 1 is incorrect. Taste from the anterior two-thirds of the tongue is transmitted by the facial nerve. The taste sensation from the posterior one-third of the B tongue is transmitted by the glossopharyngeal nerve, cranial nerve 9. So the correct answer to question is choice 3.

Front 765

In a faciolingual section through a tooth and its related gingiva, the demarcation line between free gingiva and attached gingiva extends between the1. alveolar crest and the free gingival groove.2. bottom of the gingival sulcus and the free gingival groove.3. apical margin of the epithelial attachment and the alveolar crest.4. apical margin of the epithelial attachment and the free gingival groove.

Back 765

BOTTOM OF THE GINGIVAL SULCUS AND THE FREE GINGIVAL GROOVEThe correct answer is choice 2. The gingiva may be subdivided into the attached gingiva and the free gingiva. The attached gingiva is firmly bound to the periosteum of the alveolus and to the teeth. The free gingiva lies unattached around the cervical margin of the tooth. These two regions are distinctly demarcated by the free gingival groove. When viewed from a facial lingual section, the division line between the attached and free gingiva extends between the bottom of the gingival sulcus and the free gingival groove. So the correct answer to question is choice 2.

Front 766

In a newly erupted tooth, the junction between tooth surface and the crevicular epithelium consists of which of the following?A. Interstitial crevicular fluidB. Basal lamina-like structure between enamel and epitheliumC. Basal lamina-like structure between cementum and epitheliumD. Basal lamina-like structure between dentin and epitheliumE. Keratin fibers, running from the epithelium deeply into the enamel

Back 766

BASAL LAMINA LIKE STRUCTURE BETWEEN ENAMEL AND EPITHELIUMThe correct answer is choice B. When the crown of the tooth is fully formed, eruption begins. The root continues to form. The remnants of the enamel organ, now known as reduced enamel epithelium, join with the oral mucosal epithelium above the emerging crown. The crown pushes through this combined tissue, which is now termed the junctional epithelium. This junctional epithelium can form hemi- desmosomes and a basal lamina-like structure between the epithelium and adjacent enamel at the CEJ. This is the basal lamina-like structure referred to in the question. Note that this structure only exists between enamel and epithelium as neither the root dentin nor root cementum is fully formed, and only enamel of the crown contacts the reduced enamel epithelium and mucosa on the way up. Also note that at no time is enamel pierced deeply by any fibers from the exterior. Only cementum contains fibers of the PDL. The correct answer to question is choice B.

Front 767

In a relaxed state, transitional epithelium can be distinguished from stratified squamous epithelium because transitional epithelium contains1. stratum corneum.2. flattened superficial cells.3. dome-shaped superficial cells.4. more visible ground substance.

Back 767

DOME-SHAPED SUPERFICIAL CELLSThe correct answer is choice 3. Transitional epithelium is present only in the urinary bladder and ureters. Transitional epithelium, unlike most epithelial tissue, is capable of expansion. The dome-shaped superficial cells, choice 3, can flatten when the bladder is distended with urine, thus. in effect, stretching the bladder. Choice 1 is incorrect. The stratum corneum is the superficial keratinized layer of stratified squamous epithelium, not transitional epithelium. Choice 2 is incorrect. The transitional epithelium becomes flattened when the bladder is in the expanded state, not in the relaxed state. Choice 4 is incorrect. Ground substance usually refers to material secreted by cells, such as the ground substance secreted by chondrocytes in cartilage. Its relationship to this question is unclear. So the correct answer to question is choice 3.

Front 768

In a routine demineralized histologic section of an adult tooth, the area representing enamel is generally optically clear because1. enamel is very poor in organic matrix.2. enamel is very brittle and breaks off during sectioning.3. ordinary stains do not stain the organic matrix of enamel4. the mounting medium has the same refractive index as enamel.

Back 768

ENAMEL IS VERY POOR IN ORGANIC MATRIXThe correct answer is choice 1. When demineralized sections of teeth are made, the mineral is removed and the organic matrix remains. Enamel, being approximately 95% mineral and approximately 4% water, will leave behind very little structure when demineralized and so will appear empty and clear to light. Choice 2 is incorrect as teeth are demineralized first before histologic sectioning. Choice 3 is incorrect. Stains will stain the organic matrix, but very little matrix exists. Choice 4 is incorrect. Whether or not the mounting medium has the same refractive index as the enamel or not is irrelevant, as 99% of the enamel is not there when you look at the histologic slide. So the correct answer to question is choice 1.

Front 769

In salivary glands, folds of the basal portion of the cell membrane containing mitochondria are characteristic of the1. cells composing demilunes.2. cells of the striated ducts.3. cells of the intercalated ducts.4. serous cells of the parotid gland.

Back 769

CELLS OF THE STRIATED DUCTSThe correct answer is choice 2. Striated duct cells have specialized basal portions which contain numerous mitochondria. These striated duct cells are specialized for ion transport and exchange ions in such a way that saliva has a predictable ionic composition. The mitochondria supply energy for active transport of ions. Choice 1 is incorrect. Serous demilune cells produce serous and mucous secretion, but do not accomplish the ion exchange just mentioned for the striated ducts. The demilunes are located in the submaxillary gland. Choice 3 is incorrect. The intercalated ducts cany the mucous or serous secretions from the acini where they are produced to the striated ducts where the ion content is adjusted. Choice 4, serous cells of the parotid gland, is also incorrect. The serous cells produce serous secretion which is later adjusted by the ion exchange in the striated duct. So the correct answer to question is choice 2.

Front 770

In terms of wall thickness, the relative proportion of smooth muscle is GREATEST in which of the following?A. VeinsB. VenulesC. ArteriolesD. CapillariesE. Large arteries

Back 770

ARTERIOLESThe correct answer is choice C. We should only consider choices C and E in our answers. In general, arteries have thicker smooth muscle layers(tunica media) than veins, due to the necessity of having to resist high pressures during systole. Capillaries have no smooth muscle layer at all, consisting of endothelial cells only. If we cross section both the large artery and arteriole, we find that, relative to its size, the arteriole contains a greater proportion of muscle tissue compared to the large artery, even though both are muscular. This is due to the fact that the tunica adventitia (outer layer) and tunica intima (inner layer) of the arterioles are often relatively thin. The correct answer to question is C.

Front 771

In the circulating blood of an adult, which of the following leukocytes normally appears in the highest numbers?1. Basophils2. Monocytes3. Eosinophils4. Neutrophils5. Lymphocytes

Back 771

NEUTROPHILSThe correct answer is choice 4. Leukocytes, or white blood cells, are made up of five cell types which are subdivided into two main classes, the granulocytes and the agranulocytes. The granulocytes consist of neutrophils, eosinophils and basophils. The agranulocytes consist of lymphocytes and monocytes. Neutrophils, choice 4, of the granulocyte class are the most common type of leukocytes in blood. They constitute from 55-65% of total circulating leukocytes. This is followed by lymphocytes, choice 5, monocytes. choice 2, eosinophils, choice 3, and the rarest leukocyte, the basophil. choice 1. So the correct answer to question is choice 4.

Front 772

In the developing embryo the palate is separated from the lip by a shallow sulcus in the depths of which two epithelial laminae arise. The outer lamina is theA. dental lamina for primary teeth.B. dental lamina for permanent teeth.C. primordium of the parotid gland.D. primordium of the buccal frenula.E. vestibular lamina.

Back 772

VESTIBULAR LAMINAThe correct answer is choice E. The first sign of tooth development is the formation of two thickenings, known as the primary epithelial bands, on each developing arch. The outer band eventually becomes the vestibular lamina, while the inner band becomes the dental lamina. The vestibular lamina indents and forms a furrow which separates the lips and cheeks from the alveolar processes. The dental lamina eventually forms the tooth buds (20 buds for the primary teeth). The correct answer to question is choice E.

Front 773

In the fetal heart, the foramen ovale connects the1. pulmonary artery and the aorta.2. right and the left atria, permitting the flow of blood from right to left.3. right and the left atria, permitting the flow of blood from left to right.4. right and the left ventricles, permitting the flow of blood from right to left.5. right and the left ventricles, permitting the flow of blood from left to right.

Back 773

RIGHT AND THE LEFT ATRIA, PERMITTING FLOW OF BLOOD FROM RIGHT TO LEFTThe correct answer is choice 2. The foramen ovale is a right-to-left shunt in the fetal heart connecting the two atria. Blood from the umbilical vein returns from oxygenation in the placenta and enters the fetus. Most of the oxygenated blood bypasses the liver through another fetal structure, the ductus venosus. It enters the vena cava and returns to the right atrium. Since the lungs are nonfunctioning in the fetus, the bulk of the blood is not pumped through the pulmonary system. but instead crosses to the left atrium and then to the left ventricle and aorta. So the correct answer to question is choice 2. Choice 1 refers to the ductus aneriosus, another pulmonary system bypass where blood in the pulmonary artery will bypass the lungs by traveling through the ductus arteriosus into the aorta. Anyway, the correct answer to question then is choice 2.

Front 774

In the fetus, blood enters the common carotid arteries by means of the1. aorta.2. pulmonary vein.3. pulmonary artery.4. ductus arteriosus.5. thebesian veins (venae cordis minimae).

Back 774

AORTAThe correct answer is choice 1. In the fetus as in the adult, the common carotid arteries branch from the aorta. The left common carotid branches from the aortic arch and the right common carotid from the innominate or brachiocephalic artery which branches from the aortic arch. Choices 2 and 3 are incorrect. The pulmonary system in the fetus is mostly nonfunctional, with oxygenation occurring in the placenta rather than in the lungs. Choice 4 is incorrect. The ductus venosus is a fetal structure connecting the umbilical vein to the inferior vena cava of the fetus, bypassing the fetal liver. It allows oxygenated blood from the placenta to bypass the liver and directly enter the fetal circulation. Choice 5 is incorrect. Thebesian veins or venae cordis minimae are tiny veins which return blood from the heart muscle itself into the right atrium. So the correct answer to question is choice 1.

Front 775

In the human embryo, during the third week of development, the first branchial arch divides to form the mandibular process and the1. hyoid arch.2. thyrohyoid arch.3. branchial pouch.4. maxillary process.5. frontonasal process.

Back 775

MAXILLARY PROCESSThe correct answer is choice 4. Let's review the branchial arches and what structures are derived from them. The first branchial arch forms the mandibular process and the maxillary process through the formation of Meckel's cartilage. It also produces the malleus and incus. The second and third branchial arches form the components of the hyoid bone, while the second forms the styloid process and stapes. The fourth and sixth arches form the laryngeal cartilages. So choice 1, the hyoid, is from branchial arch 2 and 3. Choice 2, the thyrohyoid arch, is also from the second and third arches. Choice 3, branchial pouches or pharyngeal pouches, exist between the branchial arches and are not products of the branchial arches. Branchial pouches or pharyngeal pouches have their own derivatives. Choice 5 is incorrect. The frontonasal process is not formed from branchial arches. So the correct answer to question is choice 4.

Front 776

In the life cycle of an ameloblast, there are cells that contain Tomes' processes. These cells are in which of the following stages?A. SecretoryB. MorphogenicC. OrganizingD. MaturativeE. Protective

Back 776

SECRETORYThe correct answer is choice A. Tome's processes are extensions of ameloblast cytoplasm into the enamel matrix. They form at the apical end of the ameloblast, and contain secretory granules with the glycoprotein matrix of the enamel. Therefore, Tome's processes are involved in enamel matrix secretion. The opposite end of the ameloblast in the secretory phase contains the nucleus and numerous mitochondria. The correct answer to question is choice A.

Front 777

In the sulcular epithelium, small spaces between cells in the stratum spinosum (prickle cell layer) are normally filled by1. keratin.2. a small amount of tissue fluid.3. capillaries that course between cells to approach the free surface.4. none of the above.

Back 777

A SMALL AMOUNT OF TISSUE FLUIDThe correct answer here is choice 2. The stratum spinosum is a cell layer within the sulcular epithelium. From the lowest underlying layer going towards the surface, the layers arc the stratum basale, the stratum spinosum, the stratum pranulosum and the stratum corneum. Reviewing the choices briefly: choice 1 is incorrect because keratin is found in the most superficial layer, the stratum corneum, but not in the stratum spinosum. It also should be noted that the keratin in the stratum corneum is contained within the cells and not between them. Choice 3 is incorrect because capillaries remain below the epithelial layer in the connective tissue layer. Choice 2 is correct. In general, all cells are surrounded by tissue fluid and this quality is not specifically applied only to sulcular epithelial stratum spinosum cells. Anyway, it is our correct answer to question.

Front 778

In the temporomandibular joint of an older person, the articulating surface of the temporal bone is covered by1. hyaline cartilage.2. elastic cartilage.3. highly cellular fibrous connective tissue.4. fibrous connective tissue containing chondrocytes.

Back 778

FIBROUS CONNECTIVE TISSUE CONTAINING CHONDROCYTESThe correct answer is choice 4. As a person becomes older, many degenerative changes occur in the body. The temporal mandibular joint is no exception. The degeneration in the temporal mandibular joint is marked by changes in the articulating surface of the temporal bone. It becomes covered by fibrous connective tissue containing chondrocytes, which produce small amounts of cartilage. This is choice 4. So the correct answer to question is choice 4.

Front 779

In which of the following are numerous afferent lymphatic channels found?A. SpleenB. ThymusC. Lymph nodesD. Palatine tonsilsE. Pharyngeal tonsils

Back 779

LYMPH NODESThe correct answer is choice C. All of the organs listed have some role in the lymphoid or immunologic system. The lymph node contains numerous afferent(inward) lymphatic channels. After lymph passes through these channels, it enters the sinuses of the node, where reticuloendothelial cells, including fixed macrophages, remove microorganisms and foreign material. The spleen contains similar reticuloendothelial cells, but they act to filter blood rather than lymph. The thymus gland produces lymphocytes and helps them specialize into "T-cell" types, but does not have incoming lymph channels. Both the palatine and pharyngeal tonsils can secrete antibodies (secretory IgA), but neither has incoming lymph channels. The correct answer to question is C.

Front 780

It is possible to distinguish histologically between the stomach and the duodenum because of the presence of1. mucosal glands in the stomach only.2. muscularis mucosa in the stomach only.3. simple columnar epithelium lining the stomach only.4. submucosal glands-in the duodenum only.5. smooth muscle in the external musculature of the duodenum only.

Back 780

SUBMUCOSAL GLANDSThe correct answer is choice 4. Let's review the choices. Choice 1 is incorrect. The stomach contains mucosal cells which secrete pepsinogen, hydrochloride acid and intrinsic factor, as well as other materials. Likewise, in the duodenum, there are mucosal glands. However, the duodenum also contains mucous-secreting glands in the submucosa, while the stomach glands are all in the mucosal layer. Choice 2 is incorrect as both the stomach and duodenum conkin a muscularis mucosa layer. Choice 5 is incorrect as both organs are surrounded by smooth muscle. Choice 3 is incorrect. Both stomach and duodenum are lined by simple columnar epithelium. So the correct answer to question is choice 4.

Front 781

Lateral clefting of the lip results from the failure of merging of1. maxillary with mandibular processes.2. maxillary processes with each other.3. maxillary and medial nasal processes.4. medial and lateral nasal processes.5. palatine processes with the nasal septum.

Back 781

MAXILLARY AND MEDIAL NASAL PROCESSESThe correct answer is choice 3. On each side of the face, the medial nasal process located at the midline of the face fuses with the maxillary process which is located further laterally. Failure to fuse can result in a cleft located slightly lateral to the midline on either the left or right side. Choice 1 is incorrect as the maxillary and mandibular processes do not normally merge. Choice 2 is incorrect. Failure of the two maxillary processes to merge is a rare event resulting in a midline cleft of the upper lip. Choice 4, failure of the medial and lateral nasal processes to join would lead to a deformation in the nasal area as the median nasal processes form the anterior nasal septum and the lateral nasal processes form the ala of the nose. Choice 5 is incorrect. Failure of the palatine process of the maxilla to merge with the nasal septum would cause a midline deformation rather than a lateral one. So the correct answer to question is choice 3.

Front 782

Long bones of the skeleton increase in length because of the1. mitotic division of osteocytes.2. mitotic division of osteoblasts.3. resorption of primary bone by osteoclasts.4. appositional growth on the cartilaginous epiphyseal plate.5. interstitial growth in the cartilaginous epiphyseal plate.

Back 782

INTERSTITIAL GROWTH IN THE CARTILAGINOUS EPIPHYSEAL PLATE.The correct answer is choice 5. Long bones such as those of the extremities have structurally distinct regions. The diaphysis makes up the shaft of the long bone. Its growth in thickness occurs by circumferential apposition of bone. The metaphyses make up the ends of the long bones. The epiphyses towards the ends of the long bones are separated from the metaphyses in a growing long bone by cartilaginous growth regions, called epiphyseal plates. Longitudinal growth occurs both proximally and distally from the epiphyseal plates by cartilage proliferation, cartilage calcification and eventually replacement by bone. So the correct answer to question is choice 5.

Front 783

Melanocytes are derived from which of the following?A. EctodermB. EndodermC. MesodermD. DermatomesE. Neural crest

Back 783

NEURAL CRESTThe correct answer is choice E. Melanocytes produce melanin, the dark colored skin pigment. They are derived from neural crest cells, which form from the neural fold area, which is originally ectoderm. Other derivatives of neural crest are craniospinal and a sympathetic ganglia, and the adrenal medulla. Mesoderm is involved in formation of the dermis while endoderm is not generally involved in skin formation. Dermatomes refer to areas of skin innervated by particular spinal nerves or groups of nerves. They are not germ layers, such as endoderm, mesoderm, etc. Note that choice A is a rational choice for this question, but choice C, neural crest, is closer to the formation of melanocytes than is ectoderm, which precedes neural crest. So our best answer to question is choice E.

Front 784

Most intrinsic muscles of the larynx receive their motor innervation from1. the laryngeal plexus.2. the inferior (recurrent) laryngeal nerve.3. the external branch of the superior laryngeal nerve.4. the internal branch of the superior laryngeal nerve.5. both external and internal branches of the superior laryngeal nerve.

Back 784

INFERIOR (RECURRENT) LARYNGEAL NERVEThe correct answer is choice 2. Intrinsic laryngeal muscles include the cricothyroid, the cricoarytenoids, the arytenoids and the thyroarytenoid. These intrinsic laryngeal muscles alter the length and shape of the vocal cords and are involved in speech production. Most receive innervation from the recurrent laryngeal branch of the vagus nerve, choice 2. The cricothyroid is an exception which is innervated by the external laryngeal branch of the superior laryngeal nerve. So choices 3 and 5 are incorrect. Choice 4 is incorrect. The internal branch of the superior laryngeal nerve is primarily sensory and not motor. Choice 1 is incorrect. The laryngeal plexus is probably meant to refer to the pharyngeal plexus which innervates the three pharyngeal constrictor muscles. The correct answer to question is choice 2.

Front 785

Most of the antibodies in the body that act against bacterial antigens are produced by1. T-lymphocytes.2. B-lymphocytes.3. macrophages.4. plasma cells.

Back 785

PLASMA CELLSThe correct answer is choice 4. Antibodies are produced by plasma cells. These plasma cells are highly differentiated former B cells. The B cells become plasma cells under the influence of antigen, antigen antibody complexes, and sometimes helper T cells. Choice 1 is incorrect. T cells do not differentiate into plasma cells or produce antibodies. T cells recognize specific antigens and are involved in cell-mediated immunity, especially against fungi and viruses. They are also involved in cytotoxicity, graft rejection, immunologic memory, and they may help B cells to differentiate into plasma cells. Choice 2 is incorrect. B cells, as mentioned, may become plasma cells, but do not themselves produce antibodies. Choice 3 is incorrect. Macrophages engulf or phagocytize bacteria and also antibody-coated bacteria, sometimes following stimulation by T cells. So the correct answer to question is choice 4.

Front 786

Most of the fibers ascending to or descending from the cerebral cortex traverse the1. pyramids2. internal capsule.3. medial lemniscus.4. cerebral peduncles.

Back 786

INTERNAL CAPSULESThe correct answer is choice 2. The cerebral cortex is the thin outer sheet of grey matter covering the cerebral hemispheres. The vast majority of the afferent and efferent projection fibers of the cerebral cortex traverse the internal capsule, choice 2. The pyramids, choice 1, are prominent longitudinal ridges that run the length of the medulla oblongata. They contain corticospinal fibers. The medial lemniscus, choice 3, is formed by fibers originating in the dorsal column nuclei which transversely cross the medulla and then turn cranially close to the midline. The cerebral peduncles, choice 4, consist of a right and a left and they make up the midbrain. So the correct answer to question is choice 2.

Front 787

Most of the lymph is returned to the blood at which of the following sites?1. Right brachiocephalic vein2. Left external jugular vein3. Junction of left internal jugular and subclavian veins4. Junction of right internal jugular and subclavian veins

Back 787

JUNCTION OF LEFT INTERNAL JUGULAR AND SUBCLAVIAN VEINSThe correct answer is choice 3. Lymph is returned to the blood through a system of lymph channels or lymph veins. These are valved structures which return fluid to the blood system. When the lymph veins collect into larger lymph vessels, the largest lymph vessel, the thoracic duct, empties into the venous system at the junction of the left subclavian and left internal jugular veins. The thoracic duct begins below the level of the diaphragm, passes through the aortic opening of the diaphragm, and begins its ascent along the right side of the vertebral column, but changes to the left before it joins the veins at the junction of the left subclavian and left internal jugular veins. So the correct answer to question is choice 3.

Front 788

Movement of the head about its vertical axis (rotation to right or left) occurs chiefly at which of the following joints?1. Atlanto-axial2. Spheno-occipital3. Atlanto-occipital4. Third to seventh cervical vertebrae

Back 788

ATLANTO-AXIALThe correct answer is choice 1. Rotation of the head occurs around the atlantoaxial joint. This refers to the joint between atlas and axis. The atlas is the first cervical vertebra while the axis is the second. In brief, the atlas can rotate on the axis which contains a peg-like projection or dens. Choice 2 is incorrect. The union between the sphenoid bone and occipital bone is osseous and no movement exists between these two bones. Choice 3, the atlantooccipital joint, refers to the union between the atlas and the occipital bone at the base of the skull. No rotational movement can occur here; only a nodding or bending movement. Some rotational movement exists in the third to seventh cervical vertebrae, but it is much less than that exhibited by the atlantoaxial joint. So the correct answer to question 50 is choice 1.

Front 789

Movement of which of the following joints causes lateral rotation of the head?A. Atlanto-axial jointB. Atlanto-occipital jointC. Costochondral jointD. Manubriosternal jointE. Temporomandibular joint

Back 789

ATLANTO-AXIALthe correct answer is A. Movement at the atlanto-axial joint (choice A) causes lateral rotation of the head. In other words, it involves moving the head in a manner as to say "no." Movement of the atlanto-occipital (choice B) joint causes flexion and extension, or nodding of the head to say "yes." Both the costochondral joint (choice C) and manubriosternal joint (choice D) are sternocostal articulations and are not associated with head movements. The temporomandibular joint (choice E) is between the mandibular fossa of the temporal bone and the condylar process of the mandible. This joint is associated with movement of the mandible.

Front 790

Normally, the free gingiva can be distinguished from the epithelial attachment because the1. underlying connective tissue of the gingiva does not contain lymphoid cells.2. epithelium of the epithelial attachment does not have rete pegs.3. epithelium of the gingiva is not keratinized.4. underlying connective tissue of the epithelial attachment is less vascular.

Back 790

EPITHELIUM OF THE EPITHELIAL ATTACHMENT DOES NOT HAvE RETE PEGSNormally, the free gingiva can be distinguished from the epithelial attachment because the1. underlying connective tissue of the gingiva does not contain lymphoid cells.2. epithelium of the epithelial attachment does not have rete pegs.3. epithelium of the gingiva is not keratinized.4. underlying connective tissue of the epithelial attachment is less vascular.

Front 791

Odontoblasts are characterized byA. being located on external surfaces of roots.B. being shed from the tooth at the time of eruptionC. differentiating first at the cervical region of a forming tooth.D. secreting a non-fibrous matrix composed of chains of amino acids.E. possessing long cytoplasmic processes which lie within dentinal tubules.

Back 791

POSSESSING LONG CYTOPLASMIC PROCESSES WHICH LIE WITHIN DENTINAL TUBULESThe correct answer is choice E. In this question, there is a problem with each of the four first choices. In roots, cementoblasts are located externally and secrete cementum. Odontoblasts are located internally and secrete dentin. Odontoblasts, being located next to the pulp, are never shed. Ameloblasts are shed after eruption, with the loss of the enamel organ. Odontoblasts specialize at the coronal end of the tooth first. The tip of the crown is formed first, enamel by ameloblasts and dentin by odontoblasts. Development then proceeds in a cervical direction. The matrix secreted by odontoblasts is a chain of amino acids(protein), but is definitely fibrous (mostly collagen). Choice E is correct. Odontoblastic processes are long cytoplasmic extensions which lie in the dentinal tubules.

Front 792

Optic nerve fibers from the nasal half of the retina cross the midline and enter the optic tract of the opposite side by way of theA. optic chiasma.B. lateral geniculate body.C. bipolar cells of the retina.D. brachium of the superior colliculus.E. geniculocalcarine tract (optic radiations).

Back 792

OPTIC CHIASMAThe correct answer is choice A. Optic nerve fibers undergo a partial decussation in the optic chiasm, with fibers from the nasal halves of each retina crossing while those from the temporal halves of each retina do not cross. Choice B is incorrect. The optic tracts which pass posteriorly from the optic chiasm terminate in the lateral geniculate bodies. These bodies give rise to neurons of the geniculocalcarine tracts (optic radiations), which pass posteriorly to the occipital cortex. Choice C is incorrect. Bipolar cells of the retina are the first neurons in the visual pathway. Choice D is incorrect. The brachium of the superior colliculus is a band of fibers which bypasses the lateral geniculate body to terminate directly in the superior colliculus. Choice E is incorrect.

Front 793

Pain fibers from the posterior third of the tongue travel with which cranial nerve?A. VagusB. FacialC. TrigeminalD. GlossopharyngealE. Hypoglossal

Back 793

GLOSSOPHARYNGEALThe correct answer is choice D. The glossopharyngeal nerve contains both general sensory and taste fibers from the posterior one-third of the tongue. Choice A is incorrect. The vagus contains some taste fibers from the most posterior portion of the tongue. Choice B is incorrect. The chorda tympani branch of the facial nerve conveys taste from the anterior two-thirds of the tongue.Choice C is incorrect. The lingual branch of V3 carries fibers which convey general sensation, including pain, from the anterior two-thirds of the tongue. Choice E is incorrect. The hypoglossal nerve is a motor nerve which supplies all intrinsic muscles of the tongue and all extrinsic muscles except palatoglossus.

Front 794

Pain, touch, temperature and proprioceptive modalities for the temporomandibular joint are carried by way of which of the following nerves?A. AuriculotemporalB. AuditoryC. TemporalD. Superior alveolarE. Inferior alveolar

Back 794

AURICULOTEMPORALThe correct answer is choice A. The auriculotemporal nerve is a sensory branch of V3 which travels within the parotid gland conveying sensory information from the face and temporomandibular joint. Choice B is incorrect. The auditory, or vestibulocochlear, nerve conveys the special senses of hearing and equilibrium from the inner ear. Choice C is incorrect. Temporal nerves are of two kinds: motor branches of CN VII, to muscles of facial expression, and deep temporal branches of V3, which supply the temporalis muscle with motor fibers. Choice D is incorrect. Superior alveolar nerves are branches of the maxillary division of the trigeminal which supply the maxillary sinus, gingiva and teeth. Choice E is incorrect. The inferior alveolar nerve is a branch of V3 which conveys sensory information from the mandibular teeth and gingiva. It also has a motor branch to mylohyoid and anterior belly of digastric.

Front 795

Parasympathetic innervation controlling salivation originates with which of the following cranial nerves?A. V,VII, IX,X,and XIIB. V,VII, IX, and XC. V, IX, and XD. VII, IX,and XIE. VII and IX

Back 795

VII AND IXThe correct answer is choice E. CN VII contains preganglionic parasympathetic fibers which travel in the chorda tympani to synapse in the submandibular ganglion. Postganglionic fibers then pass to the sublingual and submandibular salivary glands. CN IX contains fibers which travel in the tympanic nerve and lesser petrosal nerve to synapse in the otic ganglion. Postganglionic parasympathetic fibers then travel in the auriculotemporal branch of V3 to reach the parotid gland. Choice A is incorrect. CN's V and XII do not contain preganglionic parasympathetic fibers. CN X has a parasympathetic component which distributes to viscera of thorax and abdomen. Choice B is incorrect. CN V is not a parasympathetic nerve. CN X does not innervate salivary glands. Choice C is incorrect. CN V is not a parasympathetic nerve, although it does transport postganglionic parasympathetic fibers to their destinations. Choice D is incorrect. CN XI does not contain preganglionic parasympathetic fibers.

Front 796

Peripheral (lower motor neuron) lesions of cranial nerve VII will cause which of the following?A. A contralateral paralysis of the facial musculatureB. An ipsilateral flaccid paralysis of the facial musculatureC. A contralateral paralysis of only the lower facial musclesD. A contralateral paralysis of only the upper facial musclesE. An ipsilateral flaccid paralysis of only the lower facial muscles

Back 796

AN IPSILATERAL FLACCID PARALYSIS OF THE FACIAL MUSCULATUREThe correct answer is choice B. Damage to the motor root of CN VII will cause paralysis of the facial muscles on the same (ipsilateral) side as the lesion. If the nerve is damaged before it ramifies within the parotid gland, all the muscles of facial expression will be affected. Choice A is incorrect. Contralateral refers to muscles on the side of the face opposite the lesion. Choice C is incorrect. If the marginal mandibular branch of CN VII were selectively damaged, an ipsilateral paralysis of the lower facial muscles would result.Choice D is incorrect. Contralateral paralysis of only the lower facial muscles would result from a central (upper motor neuron) lesion. Choice E is incorrect.

Front 797

Pharyngotympanic (eustachian) tubes connect the nasopharynx with the1. outer ear.2. middle ear.3. semicircular canals.4. vestibule of the inner ear.

Back 797

MIDDLE EARThe correct answer is choice 2. The pharyngotympanic tube or eustachian tube connects the nasopharynx and the middle ear. It extends downward, forward and inward towards the nasopharynx. Its function is to equalize pressure against the inner and outer surfaces of the tympanic membrane. Pathologically, it is also a root by which infections may travel from the throat into the ear. The eustachian tube does not connect to the outer ear (choice 1) or the inner ear which contains the semicircular canals (choice 3) and vestibule (choice 4). It should be noted that the middle ear is the area containing the malleus, incus and stapes, known as the ear bones, hammer, anvil and stirrup. So the correct answer to question is choice 2.

Front 798

Preganglionic parasympathetic fibers pass through which of the following structures?1. Foramen ovale2. Stylomastoid foramen3. Foramen magnum and hypoglossal canal4. Superior orbital fissure and petrotympanic fissure

Back 798

SUPERIOR ORBITAL FISSURE AND PETROTYMPANIC FISSUREThe correct answer is choice 4. The cranial preganglionic neurons are found in the parasympathetic efferent nuclei of the brainstem. Their axons pass in third (or oculomotor), 7th (or facial), 9th (glossopharyngeal), and tenth (vagus) cranial nerves. The oculomotor nerve exits the cranium via the superior orbital fissure. The facial nerve passes through the skull via the stylomastoid foramen and its branch, the chorda tympani, exits via the petrotympanic fissure. The glossopharyngeal and the vagus nerves leave the cranium through the jugular foramen. Therefore, the correct answer is choice 4, superior orbital fissure and petrotympanic fissure. Choice 1, the foramen ovale, transmits the mandibular branch of the trigeminal nerve, cranial nerve V. Choice 2, the stylomastoid foramen, transmits the facial nerve, cranial nerve VII. This choice is also correct but since the question asks for all structures which preganglionic parasympathetic fibers pass through, choice 4 is the more appropriate answer. Choice 3, the foramen magnum, passes the spinal accessory, cranial nerve XI, and the hypoglossal canal transmits the hypoglossal nerve, cranial nerve XII. So the correct answer to question is choice 4.

Front 799

Primary afferent neurons in the gag reflex are carried by which of the following cranial nerves?A. Vagus (X)B. Facial (VII)C. Trigeminal (V)D. Hypoglossal (XII)E. Glossopharyngeal (IX)

Back 799

GLOSSOPHARYNGEALThe correct answer is choice E. The mucosa of the back of the throat (oropharynx) is supplied with sensory innervation by fibers from CN IX as part of the pharyngeal plexus, which is composed of fibers from CN's IX, X, and XI. Choice A is incorrect. The vagus does not convey sensory information from the oropharynx. Choice B is incorrect. The facial nerve may cany fibers conveying taste from the soft palate via the greater superficial petrosal nerve. Choice C is incorrect. Sensory fibers from the nasopharynx form the pharyngeal branch of V2, the maxillary nerve. Choice D is incorrect. The hypoglossal nerve is a motor nerve supplying the muscles of the tongue.

Front 800

Production of bile takes place in1. Kupffer cells.2. the gallbladder.3. the hepatic duct.4. the common bile duct.5. none of these.

Back 800

NONE OF THESEThe correct answer is choice 5. Bile plays an important role in digestion. The function of bile is to aid in the emulsification of fats to solubilized monoglycerides in water prior to absorption and to retard putrefaction. Bile is secreted by the hepatocytes of the liver. It is concentrated and stored in the gallbladder and emptied into the duodenum in response to a meal. Kupffer cells, choice 1, are the phagocytic cells of the liver. They remove spent erythrocytes and other particulate debris from circulation. The gallbladder, choice 2, concentrates and stores bile but does not produce it. The hepatic duct, choice 3, and the common bile duct, choice 4, are external structures of the hepatic tree. They do not produce bile. So the correct answer to question is choice 5.

Front 801

Right subclavian and right common carotid arteries arise from the1. thoracic aorta.2. ascending aorta.3. arch of the aorta.4. pulmonary artery.5. brachiocephalic artery.

Back 801

BRACHIOCEPHALIC ARTERYThe correct answer is choice 5. The brachiocephalic artery arises from the arch of the aorta and divides into the right subclavian and right common carotid arteries. By contrast, the left common carotid arises directly from the arch of the aorta -- that is incorrect choice 3 -- as does the left subclavian. So choice 3 is correct for the left side, but not for the right side. Choice 1 is incorrect. The thoracic aorta refers to the section of the aorta following the aortic arch. It gives rise to a number of branches including the bronchial arteries and the intercostal arteries. Choice 2, the ascending aorta, refers to the section of aorta beginning at the left ventricle and continuing to become the aortic arch. It gives off branches only of the right and left coronary arteries. Choice 4 is incorrect. The pulmonary artery carries deoxygenated blood to the lungs and does not give off any systemic branches. So the correct answer to question is choice 5.

Front 802

Salivary gland striated ducts are composed of which of the following types of epithelium?A. Simple squamousB. Simple cuboidalC. Stratified squamousD. Simple low columnularE. Psuedostratified ciliated columnar

Back 802

SIMPLE LOW COLUMNARThe correct answer is choice D. Striated cells of salivary gland ducts are simple(one layer) columnar cells. At their base, there is a large concentration of mitochondria which give the cell a striped appearance. The organelles provide energy for transport of water and salt ions, and are present in great numbers whenever energy need is high. Note that most acinar cells (which produce secretions)of salivary glands are simple cuboidal. The correct answer to question is choice D.

Front 803

Salivary glands of the hard palate are located in the1. median raphe.2. gingival zone.3. anterolateral zone.4. posterolateral zone.

Back 803

POSTEROLATERAL ZONEThe correct answer is choice 4. Salivary glands, which secrete a fluid called saliva, aid in the mastication, digestion and deglutition of food. These glands are present in various numbers and sizes throughout the oral cavity. In the hard palate, salivary glands are found in the submucosal layer situated in the posterolateral zone, choice 4. These glands seldom extend anteriorly beyond the line drawn from one first molar to the other. Posteriorly, they increase in size and thickness and reach far into the soft palate. So the correct answer to question is choice 4.

Front 804

Salivary, sweat, sebaceous, and von Ebner's glands all have in common the characteristic of being1. simple.2. compound.3. exocrine.4. holocrine.5. merocrine.

Back 804

EXOCRINEThe correct answer is choice 3. Glands are divided into two main categories based on their structure and function. The exocrine glands contain ducts in which their secretions leave the gland. The endocrine glands do not contain ducts but pour their secretions directly into the circulation. The exocrine glands are further subdivided into holocrine, choice 4, in which the cells composing the gland break down completely in order to liberate their secretion, apocrine, in which some of the cytoplasm at the free surface of the cells composing the gland is discharged with the secretion and merocrine, choice 5, which discharge their secretion without any fragmentation of the cytoplasm of their cells. Exocrine glands may also be described as simple, choice 1, those glands with a single unbranched duct or compound, choice 2, those glands with a branched duct system. Salivary glands are exocrine in nature and belong to a the subdivision of being compound and merocrine in secretion. Sweat glands are exocrine in nature and are simple and apocrine in secretion. Sebaceous glands are exocrine, simple and holocrine in secretion. Von Ebner's glands are also glands with ducts and are compound with merocrine secretion. These glands are all exocrine, choice 3, in nature but are all different in their subdivisions. So the correct answer to question is choice 3.

Front 805

Second, third and fourth right posterior intercostal veins drain from the right superior intercostal vein into the1. azygos vein.2. hemiazygos win.3. accessory hemiazygos vein.4. left brachiocephalic vein.5. left internal jugular vein.

Back 805

AZYGOS VEINThe correct answer is choice 1. Intercostal veins from left, right, and upper and lower ribs end up draining into different larger veins. The highest posterior intercostal vein drains into either the brachiocephalic or vertebral vein. The second, third and fourth right posterior intercostal veins drain into the superior intercostal vein which joins the azygos vein, choice 1, our correct answer. The left superior intercostal vein drains into the left brachiocephalic vein. The remaining right intercostal veins drain into the azygos and the remaining left intercostal veins drain into the hemiazygos and accessory hemiazygos veins. So we see that choices 2, 3 and 4 are incorrect but are involved in intercostal drainage. Choice 5, the internal jugular vein, is not involved in intercostal drainage. So our correct answer to question is choice 1.

Front 806

Skeletal muscle enlarges with prolonged activity as a consequence of1. differentiation of myoblasts.2. mitotic division of muscle fibers.3. an increase in endomysial connective tissue.4. an increase in sarcoplasm and in the number of myofibrils of existing muscle fibers.

Back 806

AN INCREASE IN SARCOPLASM AND IN THE NUMBER OF MYOFIBRILS OF EXISTING MUSCLE FIBERSThe correct answer is choice 4. As you know from experience, muscle size can increase through exercise over long periods of time. This is due to an increase in amount of sarcoplasm and an increased number of myofibrils. The sarcoplasm refers to the cytoplasm of the fiber which is the multinucleated muscle cell. Within each fiber are myofibrils which are the contractile elements of the fiber. So both the amount of sarcoplasm and the number of myofibrils can increase through exercise. Choice 1 is incorrect. Myoblasts are precursor cells of fibers and do not differentiate because of exercise; rather, they differentiate during embryonic muscle formation. Choice 2 is incorrect. Muscle fibers, or cells, once formed, generally do not undergo further mitosis. Choice 3 is incorrect. Endomysium is a thin connective tissue separating the individual fibers and it does not grow due to exercise. So the correct answer to question is choice 4.

Front 807

Some medications can be absorbed through the mucosa of the tongue's ventral surface and through the mucosa of the floor of the mouth. This absorption can take place in these areas because the mucosa isA. covered by pseudostratified squamous epithelium.B. covered by simple squamous epithelium with a vascular lamina propria.C. covered by thin nonkeratinized stratified squamous epithelium with a thin lamina propria.D. covered by keratinized stratified squamous epithelium that contains numerous capillaries.E. pierced by the ducts of numerous minor salivary glands through which some types of medication are easily absorbed.

Back 807

COVERED BY THIN NONKERATINIZED STRATIFIED SQUAMOUS EPITHELIUM WITH A THIN LAMINA PROPRIAThe correct answer is choice C. Some medications are taken by dissolving them under the tongue and absorbing them by diffusion. The ease of diffusion is due to the fact that the epidermis is thin in this area and is composed of stratified(1ayered) squamous(flat) cells. This epithelium is non-keratinized. Medications will diffuse most readily through non-keratinized tissue. Lamina propria refers to loose connective tissue underneath the epithelial layer. On the ventral tongue, this is also thin. The correct answer to question is choice C.

Front 808

The long axes of mandibular condyles intersect at the foramen magnum indicating that these axes are directed1. transversely.2. anteroposteriorly.3. anteromedially.4. posteromedially.5. None of the above

Back 808

The correct answer is choice 4, posteromedially..... The foramen magnum is the large foramen at the base of the skull through which the spinal fl cord will pass. Review a model diagram or preserved specimen of a mandible and a skull for this question. The condyle of the mandible terminates in pointed areas known as the medial and lateral poles. Lines drawn through the poles from each side will extend horizontally medially and posteriorly until they meet near the anterior border of the foramen magnum. This is, therefore. a medial and posterior direction, choice 4. It is said that this line is parallel to a line connecting the buccal and lingual cusps of the premolar and molar teeth although the significance of this parallelism is not known. Anyway, the correct answer to question is choice 4.

Front 809

The lymph from the upper lateral quadrant of the mammary gland primarily drains into theA. Anterior (pectoral) axillary nodesB. Central axillary nodesC. Infraclavicular (deltopectoral) axillary nodesD. Lateral axillary nodes

Back 809

The correct answer is A, the anterior (pectoral) axillary nodes..... The axillary lymph nodes drain lymph vessels from the lateral quadrants of the breast, superficial lymph vessels of the thoracoabdominal walls above the umbilicus and the vessels from the upper limb. The lymph from the upper lateral quadrant of the mammary gland primarily drains into the anterior (pectoral) axillary nodes (choice A). The central axillary nodes (choice B) receive lymph from the anterior, posterior and lateral axillary lymph nodes. The infraclavicular (deltopectoral) axillary nodes (choice C) receive lymph from the lateral'side of the hand, forearm and arm. The lateral axillary nodes (choice D) receive most of the lymph from the upper arm and the posterior (subscapular) axillary nodes (choice E) receive lymph vessels from the back extending down as far as the iliac crest.

Front 810

The lymph vessels that drain both dental arches connect directly with which of the following nodes?A. SubmandibularB. Deep cervicalC. SublingualD. RetropharyngealE. Superficial cervical

Back 810

The correct answer is choice A, the submandibular nodes.... Gingival and dental lymphatic vessels drain to the submandibular nodes of their respective sides. An exception is the region of the lower four incisor teeth, which drain to submental lymph nodes. Choice B is incorrect. All head and neck lymphatics drain ultimately to deep cervical nodes, either directly or indirectly. Submandibular nodes drain to deep cervical nodes. Choice C is incorrect. Sublingual nodes are small and variable. They drain to deep cervical nodes. Choice D is incorrect. Retropharyngeal nodes receive afferents from the nasopharynx and Eustachian tube. They drain to deep cervical nodes. Choice E is incorrect. Superficial cervical nodes receive lymph from the external ear and lower parotid region. They drain to deep cervical nodes.

Front 811

The mandible, except for the condyle, is principally formed by1. endochondral ossification.2. intramembranous ossification.3. expansion of the dental lamina.4. the conversion of Meckel's cartilage directly into bone.

Back 811

The correct answer is choice 2, intramembranous ossification..... The mandible ossifies in membrane (intramembranous ossification) from two centers that appear close to the site of the future mental foramen during the sixth week of intrauterine life. The Meckel's cartilage provides a framework around which the mandible forms. Between the 10th and 14th week, three secondary cartilages develop within the growing mandible. The largest and most important of these is the condylar cartilage. In short, the mandible is principally formed by intramembranous ossification while the condyle is formed by secondary cartilage. So the correct answer to question is choice 2.

Front 812

The middle constrictor muscle of the pharynx originates from the1. hyoid bone.2. thyroid cartilage.3. pterygoid hamulus.4. pterygomandibular raphe.

Back 812

The correct answer is choice 1, the hyoid bone.... The middle constrictor muscle connects the lower section of the stylohyoid ligament to the greater and lesser horns of the hyoid bone. It is involved in involuntary contraction during swallowing. Choice 2 is incorrect. The thyroid cartilage has muscle attachments for the cricothyroid muscle. Choice 3 is incorrect. The pterygoid hamulus is a process around which the tensor veli palatini muscle hooks. The tensor veli palatini tightens and flattens the soft palate. Choice 4 is incorrect. Pterygomandibular raphe is a frbrous line of connective tissue which attaches to the superior constrictor and buccinator muscles. So the correct answer to question is choice 1.

Front 813

The middle nasal concha is part of which of the following bones?1. Nasal2. Vomer3. Ethmoid4. Palatine5. Sphenoid

Back 813

The correct answer is choice 3, the ethmoid bone....The ethmoid bone consists primarily of the two lateral masses, one on each side of the nasal cavity. It is notable for containing the cribriform plate through which the olfactory and anterior ethmoidal nerves pass. It also contains many hollow air cells and both the superior and middle conchae of the nose. Choice 1, the nasal bones, a seemingly logical choice, do not contain any conchae of the nose. The two nasal bones are small and border on the nasal cartilage, the nasal spine of the m frontal bone, the perpendicular plate of the ethmoid, and the maxilla. The vomer, choice 2, forms the posterior part of the nasal septum and does not contain a nasal concha. Choice 4, the palatine bone, borders on the inferior nasal concha which is a separate bone, as does the maxilla. Choice 5, the sphenoid, also does not contain the nasal conchae. So the correct answer to question is choice 3.

Front 814

The middle pharyngeal constrictor muscle originates from the1. hyoid bone.2. thyroid cartilage.3. pterygoid hamulus.4. pterygomandibular raphe.

Back 814

The correct answer is choice 1, the hyoid bone.... The middle pharyngeal constrictor muscle arises from the whole length of the superior border of the greater horn of the hyoid bone, from the lesser horn, and from the inferior end of the stylohyoid ligament. The fibers course posteriorly to be inserted into the median raphe. So the correct answer to question is choice 1.

Front 815

The most common immunoglobulin found in mucosal secretions of the respiratory and gastrointestinal tract and colostrum isA. IgAB. IgDC. IgED. IgGE. IgM

Back 815

The correct answer is A, IgA.... Immunoglobulin A (IgA) (choice A) helps to defend against bacteria on mucosal surfaces. When IgA is deficient, there is an increased susceptibility to infections, especially upper-respiratory infections. IgD (choice B) plays a minor role in the bodies immune system. IgE (choice C) is primarily involved in allergic reactions. Both IgG (choice D) and IgM (choice E) are involved in the majority of all bacterial infections. These antibodies, as well as IgA, IgD and IgE, protect the body by directly attacking the "invader" as well as activating the complement system.

Front 816

The most prominent functional component in the tunica media of small arteries is1. elastic fibers.2. smooth muscle.3. striated muscle.4. reticular fibers.5. collagenous fibers

Back 816

The correct answer is choice 2, smooth muscle.....Arteries consist of a tunica intima or inner layer, a tunica media or middle layer, and a tunica adventitia or outer layer. The tunica intima generally contains epithelium and elastic fibers. The tunica media is generally composed of smooth muscle with some few reticular fibers, elastic fibers and collagen fibers. However, the major distinguishing component is smooth muscle. The tunica adventitia is characterized by collagen fibers. So, reviewing our choices: choice 1, elastic fibers are present in the tunica media but are not the most prominent; choice 3, striated muscle is not present in the artery; choice 4, reticular fibers are present in the tunica media but are, again, not the most prominent; choice 5, collagen fibers are characteristic of the tunica adventitia, not the tunica media. So the correct answer to question is choice 2.

Front 817

The most vascular portion of the temporomandibular joint's articular disk is usually found on the disk's1. periphery.2. superior surface.3. inferior surface.

Back 817

The correct answer is choice 1, the periphery.... The temporal mandibular joint is the synovial articulation between the mandible and the cranium. A fibrocartilage biconcave articulating disks interposed between the rounded condyle of the mandible and the corresponding articular surface of the temporal bone. The articulatlng disk is supplied by an impressive compact crown of interwined capillary twigs hugging the thick rim of the avascular fibrous disk. The most vascular portion of the disk, therefore, is found on the periphery. So the correct answer to question 16 is choice 1.

Front 818

The muscle that is the prime mover in left lateral excursion is theA. right masseter.B. left medial pterygoid.C. right medial pterygoid.D. left lateral pterygoid.E. right lateral pterygoid

Back 818

The correct answer is choice E, right lateral pterygoid..... Acting together, the lateral pterygoids protrude the mandible and open the jaw. Acting individually, they cause movement of the mandible to the opposite side (right lateral pterygoid moves the mandible to the left). Choice A is incorrect. The major function of the masseter is to elevate the mandible (close the jaw). Choice B is incorrect. Acting together, the medial pterygoids elevate the mandible. Choice C is incorrect. Choice D is incorrect.

Front 819

The nerves in dental pulp are1. afferent only.2. sympathetic only.3. parasympathetic only.4. afferent and sympathetic.5. afferent and parasympathetic.

Back 819

The correct answer is choice 4, afferent and sympathetic.... Compared to a similar volume of connective tissue elsewhere in the body, the dental pulp is richly innervated. The pulp is supplied with thick bundles of myelinated fibers with fine nonmyelinated terminals extending into the predentin, some of which may run through the dentinal tubules to he dentin. These fibers are both afferent or sensory and sympathetic, choice 4. It's important to note that there are no motor nerves to the dental pulp and no parasympathetic nerves to the dental pulp. So the correct answer to question is choice 4.

Front 820

The nucleolus produces1. DNA.2. transfer RNA.3. ribosomal RNA.4. messenger RNA.5. both (1) and (2) above

Back 820

The correct answer is choice 3, ribosomal RNA..... The nucleolus of the cell located within the nucleus is composed of and produces rRNA or ribosomal RNA. rRNA comprises the bulk of the structure of the ribosome. Choice 1 is incorrect. DNA is produced by replication in the nucleus, but outside of the nucleolus. Choice 2 is incorrect. Transfer RNA is also synthesized in the nucleus, but not in the nucleolar region. Choice 4 is incorrect. Messenger RNA is produced by transcription from the DNA in the nucleus, but outside of the nucleolus. So the correct answer to question is choice 3.

Front 821

The number of roots that are formed is determined by the1. thickness of the cervical loop.2. number of root sheaths developed by the enamel organ.3. number of discontinuities developed in the root sheath.4. number of medial ingrowths of the cervical loop.

Back 821

The correct answer is choice 4, the number of medial ingrowths of the cervical loop..... After full formation of enamel, the inner and outer enamel epithelium meet to form the cervical loop, the tip of which becomes Hertwig's root sheath. The Hertwig root sheath will cause root formation through induction of the cells of the dental papilla to become odontoblasts. As the cervical loop forms inpockets or ingrowths, various numbers of roots will form. Choice 1 is therefore incorrect. Likewise, choice 2 is incorrect. The enamel organ itself does not form the root sheath. It is only the inner and outer enamel epithelium at their tip which form the root sheath and only after enamel formation is complete. Choice 3 is incorrect. Hertwig's root sheath is perforated by dental sac tissue which will become the periodontal ligament. However, these perforations are not involved in determining the number of roots. So the correct answer to question is choice 4.

Front 822

The obliquus superior muscle is innervated by which of the following nerves?A. AbducentB. AccessoryC. OculomotorD. OpticE. Trochlear

Back 822

The correct answer is E, the trochlear nerve..... The trochlear nerve (choice E) is involved with ocular movement and innervates the obliquus superior muscle. The abducent nerve (choice A) is also involved with ocular movements. It innervates the rectus lateralis muscle. The accessory nerve (choice B) innervates various muscles in the pharynx, larynx, and shoulders, including sternocleidomastoid and trapezius. It is involved with swallowing, phonation, and movements of the head and shoulder. The oculomotor nerve (choice C) is responsible for ocular movement, contraction of the pupil and accommodation. This nerve innervates various eye muscles, including the obliquus inferior. The optic nerve (choice D) is responsible for vision and innervates rods and cones of the retina.

Front 823

The optic tracts consist of axons from which of the following cells?1. Rod2. Bipolar3. Ganglion4. Horizontal5. All of the above

Back 823

The correct answer is choice 3, ganglion cells..... Let's review the cells associated with vision. The sensory cells, rods, choice 1, and cones lie in the external layer of the retina and activate the bipolar cells (choice 2) of the middle layer. The innermost layer contains ganglion cells (choice 3), our correct answer. The fibers of the ganglion cells converge to form the optic nerve and optic tract to the visual cortex. Choice 4, horizontal cells, lie in the middle layer of the retina and interconnect rods, cones, ganglion cells and bipolar cells. The correct answer to question is choice 3.

Front 824

The organelle that binds and releases calcium during relaxation and contraction of skeletal muscle is a1. nucleus.2. lysosome.3. mitochondrion.4. transverse tubule.5. sarcoplasmic reticulum

Back 824

The correct answer is choice 5, the sarcoplasmic reticulum..... The sarcoplasmic reticulum releases calcium ions when muscles contract and binds them during muscle relaxation. The sarcoplasmic reticulum tubules run parallel to the muscle fibers. Choice 1, nucleus, is incorrect. The nucleus stores genetic material in the form of DNA and directs the cell's activities. Choice 2 is incorrect. The lysosome stores digestive enzymes within a membrane. Choice 3 is incorrect. The mitochondrion produces ATP molecules through oxidative phosphorylation and the oxidative degeneration of glucose. Choice 4 is incorrect. The transverse tubules are separate from the sarcoplasmic reticulum. They extend transversely into the sarcoplasm and are invaginations of the sarcolemma membrane. They are not involved in calcium binding or calcium release. So the correct answer to question is choice 5.

Front 825

The organic matrix of dentin is synthesized by which of the following?A. AmeloblastsB. CementocytesC. OdontoblastsD. OsteoblastsE. Osteocytes

Back 825

The correct answer is C, odonotoblasts..... Teeth are composed of a core pulp surrounded by a mineralized dentin, which is covered by a mineralized enamel on the crown and a mineralized cementum on the root. Dentin contains an organic matrix composed of collagen and proteoglycans synthesized by odontoblasts (choice C). Ameloblasts (choice A) produce the hardest substance of the human body known as enamel. Cementocytes (choice B) produce a calcified tissue similar to that of bone that covers the dentin of the root. This substance is called cementum. Osteoblasts (choice D) are the basophilic cells that actively secrete bone matrix and osteocytes (choice E) are mature bone cells.

Front 826

The parotid duct pierces the buccinator muscle opposite the1. mandibular first premolar.2. maxillary first premolar.3. maxillary first molar.4. maxillary second molar.5. maxillary third molar.

Back 826

The correct answer is choice 4, maxillary second molar.... The parotid gland is the largest of the paired salivary glands and contains serous rather than mucous acini, and is located in a space roughly bordered by the styloid process, the external auditory meatus and the mastoid process. The parotid duct or Stensen's duct leaves the anterior border of the gland and pierces the buccinator muscle to enter the oral cavity on the buccal surface opposite the second maxillary molars. Of the incorrect choices, it should be noted that the sublingual and submandibular glands empty into the floor of the mouth and might be considered to be opposite the mandibular teeth. The submandibular gland drains through Wharton's duct into the floor of the mouth, while the sublingual gland drains through a large number of openings in the floor of the mouth. So the correct answer to question is choice 4.

Front 827

The point on the lateral aspect of the skull where the greater wing of the sphenoid, parietal, frontal and temporal bones converge is known as theA. AsterionB. BregmaC. LambdaD. PterionE. Stephanion

Back 827

The correct answer is D, pterion...... The point on the lateral aspect of the skull where the greater wing of the sphenoid, parietal, frontal and temporal bones converge is known as the pterion (choice D). The asterion (choice A) is the point of meeting of the parietomastoid, occipitomastoid and lambdoidal sutures. The bregma (choice B) is the point at which the coronal suture intersects the sagittal suture and is the site of the anterior fontanelle in an infant. The lambda (choice C) is the point at which the sagittal suture intersects the lamboid suture and is the site of the posterior fontanelle in an infant. The stephanion (choice E) is the point where the superior temporal line cuts the coronal suture.

Front 828

The postcentral gyrus is located in the1. insula.2. frontal lobe.3. temporal lobe.4. parietal lobe.5. occipital lobe.

Back 828

The correct answer is choice 4, the parietal lobe..... The postcentral gyrus is the primary sensory area of the brain receiving general sensation from the contralateral side of the body via relays in the thalamus. The postcentral gyrus is located in the parietal lobe, choice 4, of the brain. So the correct answer to question is choice 4.

Front 829

The posterior cervical triangle is bounded partly by1. trapezius and subclavius muscles.2. splenius capitis and trapezius muscles.3. trapezius and sternocleidomastoid muscles.4. the clavicle and the longus colli muscle.

Back 829

The correct answer is choice 3, trapezius and sternocleidomastoid muscles..... The side of the neck is often thought of as being divided into two triangles. The sternocleidomastoid muscle divides the area into an anterior and posterior triangle. The posterior triangle is bounded by the clavicle, the posterior border of the stenzocleidomastoid and the anterior border of the trapezius. The anterior triangle is bordered by the anterior side of the sternocleidomastoid, the lower border of the mandible, and the midline of the neck. Choice 1 is incorrect. The subclavius is a muscle located underneath the pectoralis major and inserts on the clavicle and first rib. Choice 2 is incorrect. The splenius capitis is a muscle which extends the head and neck and is located in the floor of the posterior triangle and inserts on the mastoid process. Choice 3 is incorrect. The longus colli is a muscle of the prevertebral group and inserts on the vertebrae. So the correct answer to question is choice 3.

Front 830

The posterior cord of the brachial plexus gives rise to which of the following nerves?1. Radial2. Long thoracic3. Thoracoacromial4. Medial pectoral5. Lateral pectoral

Back 830

The correct answer is choice 1, the radial nerve...... The brachial plexus is a network of nerves which provides innervation primarily to the upper extremity. It is subdivided into roots, trunks, divisions and cords. Each of these are then further named according to the positions in the plexus. For example, the cords are referred to as lateral, medial and posterior cords. The radial nerve, choice I, is a branch of the posterior cord. The long thoracic nerve, choice 2, originates from the roots of the brachial plexus. The thoraco-acromial, choice 3, usually refers to a large artery and its branches that supply the upper extremity. The medial pectoral nerve, choice 4, branches off the medial cord and the lateral pectoral nerve, choice 5, branches off the lateral cord. So the correct answer to question is choice 1.

Front 831

The postganglionic sympathetic fibers to the vessels of the submandibular salivary gland arise from cells in the1. otic ganglion.2. submandibular ganglion.3. pterygopalatine ganglion.4. superior cervical ganglion.

Back 831

The correct answer is choice 4, the superior sympathetic ganglion...... The submandibular salivary gland folds around the posterior edge of the mylohyoid muscle so that one section is within the oral cavity and the other is outside. It is innervated by parasympathetic secretomotor fibers from cranial nerve 7, the facial nerve. These post-ganglionic fibers begin in the submandibular ganglion, choice 2. However, post-ganglionic sympathetic fibers also innervate the gland. These fibers come from synapses in the superior cervical ganglion which contains the synapse between the post-ganglionic fibers and the pre-ganglionic fibers which run up from the thoracic vertebrae into the inferior, middle and superior cervical ganglia. So our correct answer is choice 4. Choice 1 is incorrect. The otic ganglion contains cell bodies of post-ganglionic fibers which are secretomotor to the parotid gland. The post-ganglionic fibers travel via the auriculotemporal nerve. The pre-ganglionic neurons originate with cranial nerve 9, the glossopharyngeal. Choice 3 is incorrect. The pterygopalatine ganglion contains post-ganglionic fibers which are secretomotor to the lacrimal, nasal and palatine glands. So the correct answer to question is choice 4.

Front 832

The presence of valves characterizes1. veins only.2. blood sinusoids only.3. lymphatic vessels only.4. veins and lymphatic vessels.5. blood sinusoids and blood capillaries.

Back 832

The correct answer is choice 4, veins and lymphatics..... Within the circulatory system, valves can be found in veins of more than 2mm in diameter and in small and medium sized lymphatic vessels, choice 4. Blood sinusoids, choice 2, are capillaries of wide diameter but do not contain valves. Blood capillaries, choice 5, are small blood vessels with diameters similar to that of a red blood cell and in general, these do not have valves. So the correct answer to question is choice 4.

Front 833

The primary histologic characteristic of the pancreas is1. follicles filled with secretion.2. groups of special cells scattered among glandular alveoli.3. small groups of cells scattered between follicles.4. cells arranged in layers among which are special cells.

Back 833

The correct answer is choice 2, groups of specialized cells scattered among glandular alveoli..... The pancreas is both an exocrine and endocrine gland. The exocrine cells produce digestive enzymes and their enzymatic secretions enter ducts which eventually enter the duodenum. Scattered within areas of exocrine cells are endocrine areas of cells called islets of Langerhans. These areas contain alpha cells which produce glucagon and beta cells which produce insulin. Their endocrine secretions pass directly into the blood stream without passing through ducts. Choices 1 and 3 are incorrect. The term "follicle" is usually used to describe hair follicles or ovarian follicles and applies a large area filled with a substance or secretion, such as an ovum or a hair. Large areas filled with enzyme or hormone do not exist in the pancreas. Choice 4 is incorrect as there is no layered arrangement of cells in the pancreas. So the correct answer to question is choice 2.

Front 834

The ribonucleic acid involved in protein synthesis is found primarily in the1. nucleolus.2. mitochondria.3. Golgi apparatus.4. fluid ground substance.5. granular endoplasmic reticulum.

Back 834

The correct answer is choice 5, granular endoplasmic reticulum....... Proteins are not only a major structural component of cells but in the form of enzymes mediate every metabolic process within the cell. Protein synthesis is therefore an essential and continuous activity of all cells. The process involves the transcription of the DNA code to a messenger RNA in the nucleus which then enters into the cytoplasm to associate with ribosomes upon which protein synthesis can occur. The principal organelles are therefore the nucleus and ribosomes in which the DNA and RNA respectively are primarily found. Ribosomes are found free in the cytoplasm but the majority are found on the surface of granular endoplasmic reticulum. In summary, the ribonucleic acid, RNA, involved in protein synthesis is found primarily in the granular endoplasmic reticulum, choice 5. Nucleolus, choice 1 , found in the nucleus of some cells, is the site of ribosomal RNA synthesis. Mitochondria, choice 2, and Golgi apparatus, choice 3, are described in previous questions. The mitochondria produce ATP from glucose and other food molecules and the Golgi apparatus packages prepared proteins for secretion by the cell. Fluid ground substance, choice 4, an organic material, serves as the matrix of the extracellular material present in connective tissue. So the correct answer to question is choice 5.

Front 835

The root (radix linguae) of the tongue is connected to the hyoid bone by what two muscles?A. Chondroglossus and StyloglossusB. Genioglossus and StyloglossusC. Hyoglossus and GenioglossusD. Palatoglossus and HyoglossusE. Styloglossus and Palatoglossus

Back 835

The correct answer is C, hyoglossus and genioglossus..... The root (radix linguae) of the tongue is connected to the hyoid bone by the Hyoglossus and Genioglossus muscles (choice C) and the hyoglossal membrane. The Chondroglossus muscle is often considered to be part of the Hyoglossus, but is separated from it by fibers of the Genioglossus muscle. The Palatoglossus muscle is primarily associated with the soft palate and the Styloglossus muscle arises from the anterior and lateral surfaces of the styloid process.

Front 836

The roots of the brachial plexus are derived from the ventral rami ofA. the cervical plexus.B. the spinal accessory nerve.C. spinal nerves C3 through C5D. spinal nerves C3 through C7.E. spinal nerves C5 through T1.

Back 836

The correct answer is choice E, C5 to T1........ The ventral primary rami of the lower four cervical nerves and the first thoracic nerve participate in the formation of the brachial plexus. Choice A is incorrect. The cervical plexus is derived from the ventral primary rami of the first four cervical nerves. It is a somatic plexus consisting of cutaneous branches, motor branches to several neck muscles, and the phrenic nerve. Choice B is incorrect. The spinal accessory is a cranial nerve (CN XI) which includes a spinal root derived from upper cervical segments. The spinal portion is responsible for innervation of sternocleidomastoid and trapezius. Choice C is incorrect. Cervical spinal nerves 3,4 and 5 contribute to the phrenic nerve. Choice D is incorrect. Spinal nerves C3 and C4 participate in the cervical plexus. C5,6 and 7 contribute to the brachial plexus.

Front 837

The secretion of which of the following with development of the tongue EXCEPT the endocrine glands is NOT essential to life?1. Parathyroids2. Adrenal cortex3. Adrenal medulla4. Anterior pituitary5. Pancreatic islets (Langerhans)

Back 837

The correct answer is choice 3, the adrenal medulla...... The adrenal or suprarenal medulla, which produces epinephrine and norepinephrine, is not essential to life. The parathyroids, choice 1, produce parathyroid hormone which raises blood calcium through bone resorption. Steady blood calcium level is essential. The adrenal cortex, choice 2, produces aldosterone which aids in sodium resorption, as well as I cortisone and many glucocorticoids and mineral corticoids. As these are involved in ion balance, the adrenal cortex is essential to life. Choice 4, the anterior pituitary, is the so-called master gland and, as such, controls many other glands. It produces, among other 1 hormones. GH, FSH. LH, ACTH and TSH. It is considered essential to life. The pancreatic islets produce both glucagon, which raises blood sugar, and insulin, which lowers blood sugar. Since blood sugar control is essential, the pancreas is also essential to life. So the correct answer to question is choice 3.

Front 838

The semicircular canals of the middle ear send information relating to equilibrium to which of the following nuclei of the reticular formation?A. Interstitial nucleusB. Nucleus ambiguusC. Olivary nucleusD. Solitary nucleusE. Vestibular nucleus

Back 838

The correct answer is E, vestibular nucleus....... The vestibular nucleus (choice E) is divided into four separate subdivisions, each of which receives signals from the semicircular canals of the middle ear relating to equilibrium. These four subdivisions correct the movement of the eyes, neck, head, as well as other portions of the body. The interstitial nucleus (choice A) is responsible for only the rotational movements of the head and eyes. The nucleus ambiguus (choice B) supplies motor fibers to skeletal muscles. The olivary nucleus (choice C) is associated with the auditory pathway. The solitary nucleus (choice D) receives information on taste sensations.

Front 839

The structure first formed by the tooth bud that remains in evidence in the formed tooth is the1. primary cuticle.2. secondary cuticle.3. inner enamel epithelium.4. cementoenamel junction.5. dentinoenamel junction

Back 839

The correct answer is choice 5, the dentinoenamel junction....... Let's review the choices briefly. The primary cuticle consists of the outer layer of enamel which is not mineralized when enamel formation is complete. Together with the nonfunctioning leftover enamel organ, they form Nasmyth's membrane which is present on the tooth surface when it erupts. Secondary cuticle, choice 2, refers to an older term for a keratinized reduced enamel epithelium prior to eruption. It will not remain after eruption. Inner enamel epithelium, choice 3, is the layer of the tooth bud that causes cells of the dental papilla to differentiate into odontoblasts. The layer itself will later become the ameloblasts and will later form enamel, and then after that, it will degenerate and sections will form the epithelial rests of Malassez. The cemento-enamel junction, choice 4, forms as cementoblasts deposit cementum on the surface of root dentin, but the CEJ is formed later than choice 5, the dentino-enamel junction. The dentino-enamel junction first forms as ameloblasts and odontoblasts begin to lay down enamel and dentin, respectively. The DEJ remains in the formed tooth and it is the first structure formed which remains in the formed tooth. So the correct answer to question is choice 5.

Front 840

The submucosa is present in each of the following EXCEPT one. Which one is this EXCEPTION?A. ColonB. StomachC. JejunumD. GallbladderE. Duodenum

Back 840

The correct answer is choice D, the gallbladder...... Note that choices A, B,C and E are all part of the alimentary canal, while choice D, the gall bladder is an accessory gland. The layers of the alimentary canal include, from the inside out, the epithelium(of various types), a lamina propria of connective tissue underneath the epithelium, the submucosa of loose connective tissue, circular and longitudinal muscle layers, and the outer loose connective tissue, the tunica adventitia(in the esophagus) or serosa (in the stomach and intestines). By contrast, the wall of the gall bladder contains epithelium, lamina propria, muscle layers, a perimuscular connective tissue layer and a serosa. Note that no submucosal layer is found in the gallbladder. The correct answer to question is choice D.

Front 841

The superior and inferior ophthalmic veins drain directly or indirectly into theA. frontal vein.B. cavernous sinus.C. anterior facial vein.D. internal jugular vein.E. superior petrosal sinus.

Back 841

The correct answer is choice B, the cavernous sinus....... The ophthalmic veins join the sphenoparietal sinus which travels along the lesser wing of the sphenoid to form the cavernous sinus. Choice A is incorrect. The frontal vein, when present, is a tributary of the superior ophthalmic vein. Choice C is incorrect. Anterior facial vein is archaic terminology for the facial vein, which begins as the angular vein at the side of the nose and terminates by joining the anterior limb of the retromandibular vein to form the common facial vein. Choice D is incorrect. The internal jugular vein is the direct continuation of the sigmoid sinus. It receives the inferior petrosal sinus directly. Choice E is incorrect. The superior petrosal sinus, along with the inferior petrosal sinus, drains the cavernous sinus posteriorly.

Front 842

The superior laryngeal artery pierces the thyrohyoid membrane in company with which of the following laryngeal nerves?A. lnferior laryngealB. Internal laryngealC. External laryngealD. Superior laryngealE. Recurrent laryngeal

Back 842

The correct answer is choice B, the internal laryngeal nerve..... The internal laryngeal nerve, a purely sensory branch of the superior laryngeal branch of the vagus, pierces the thyrohyoid membrane to supply the mucosa of the larynx above the vocal folds. Choice A is incorrect. The inferior laryngeal nerve is the terminal portion of the recurrent laryngeal nerve. It enters the larynx by passing deep to the inferior border of the inferior constrictor muscle, along with the inferior laryngeal artery. Choice C is incorrect. The external laryngeal nerve does not supply the interior of the larynx. It innervates the cricothyroid muscle. Choice D is incorrect. The superior laryngeal nerve divides to form the internal and external laryngeal nerves. Choice E is incorrect. The recurrent laryngeal nerve is a mixed nerve which supplies all intrinsic laryngeal muscles except cricothyroid, and conveys sensation from the laryngeal mucosa below the vocal folds. Its terminal portion is the inferior laryngeal nerve.

Front 843

The temporalis muscle inserts into theA. coronoid process.B. condylar process.C. fovea of the mandible.D. lateral aspect of the mandibular angle.E. articular disk of the temporomandibular joint.

Back 843

The correct answer is choice A, the coronoid process...... The fibers of temporalis converge to a tendon which inserts primarily on the coronoid process of the mandible. Choice B is incorrect. The condylar process, or head and neck of the mandible, is the site of insertion of the lateral pterygoid muscle. Choice C is incorrect. Most of the fibers of the lateral pterygoid muscle insert into the depression on the neck of the mandible known as the fovea. Choice D is incorrect. The masseter inserts on the lateral aspect of the ramus of the mandible, including its angle. Choice E is incorrect. The lateral pterygoid may contain fibers which insert directly into the articular disk.

Front 844

The tendon of the tensor veli palatini muscle curves around the1. angular spine.2. styloid process.3. pterygoid hamulus.4. lateral pterygoid plate.5. spine of the sphenoid.

Back 844

The correct answer is choice 3, the pterygoid hamulus...... The tensor veli palatini muscle arises from the sphenoid bone and from the lateral surface of the auditory tube. It inserts into the aponeurosis of the soft palate and onto the posterior edge of the bony hard palate. The tensor veli palatini curves around the pterygoid hamulus, choice 3, before reaching its final insertion pulling the soft palate laterally when it contracts. This prevents the passage of a bolus of food from forcing the soft palate upwards into the nasal part of the pharynx. The tensor veli palatini is innervated by the motor division of the trigeminal nerve. So the correct answer to question is choice 3.

Front 845

The thick myofilaments observed in transmission electron microscopic preparations of skeletal muscle are1. composed mainly of actin.2. present only in the A band.3. present in both A and I bands.4. traversed or crossed by the Z band.

Back 845

The correct answer is choice 2, present only in the A band....... It will be helpful to review a diagram from your home study notes or your text when checking this question. A-bands consist of thick myofilaments made up of myosin. I-bands consists of thin myofilaments made up of actin. I-bands, or actin filaments, connect to Z-lines or bands. So choice 2 is correct. Choice 1 is incorrect because thick myofilaments are myosin, not actin. Choice 3 is incorrect because I-bands consist of only actin, not myosin. Choice 4 is incorrect because only actin I-bands join the Z-band. Myosin A-bands do not connect to the Z-band. So the correct answer to question is choice 2.

Front 846

The thoracic duct empties directly into the junction of theA. superior vena cava and the azygos vein.B. left jugular and brachiocephalic veins.C. right jugular and brachiocephalic veins.D. left internal jugular and subclavian veins.E. right internal jugular and subclavian veins.

Back 846

The correct answer is choice D, the left jugular and subclavian veins...... The thoracic duct terminates at the beginning of the left brachiocephalic vein (junction of left internal jugular and subclavian veins). Choice A is incorrect. The azygos vein arches over the root of the right lung to empty into the superior vena cava before it enters the right atrium. Choice B is incorrect. The external jugular vein terminates by joining the subclavian vein. Choice C is incorrect. Choice E is incorrect. The right lymphatic duct terminates by joining the junction of the right internal jugular and right subclavian veins. It drains lymph from the upper right quadrant of the body, and may also drain a portion of the left lung.

Front 847

The three divisions of the trigeminal nerve pass through openings in which of the following bones?A. FrontalB. SphenoidC. TemporalD. ParietalE. Occipital

Back 847

The correct answer is choice B, the sphenoid bone...... Superior orbital fissure is located between the greater and lesser wings of the sphenoid. Foramen rotundum and foramen ovale are found in the greater wing. Choice A is incorrect. The frontal bone forms much of the floor of the anterior cranial fossa. Choice C is incorrect. The temporal bone contains the internal auditory meatus. which transmits CN's VII and VIII. Choice D is incorrect. The parietal bone does not contribute to the floor of the cranial cavity. Choice E is incorrect. The occipital bone forms much of the floor of the posterior cranial fossa. It contains foramen magnum and the hypoglossal canal, and forms a boundary of the jugular foramen, which transmits CN's IX, X, and XI and the internal jugular vein.

Front 848

The trigeminal nerve innervates exclusively which of the following muscles or muscle parts?A. Buccinator and masseterB. Mylohyoid and geniohyoidC. Medial and lateral pterygoidD. Tensor and levator veli palatiniE. Anterior and posterior bellies of digastric

Back 848

The correct answer is choice C, the medial and lateral pterygoids....... The medial and lateral pterygoid muscles are two of the four muscles of mastication, which are derived from the first pharyngeal arch. The nerve of the first (mandibular) arch is V3, the mandibular nerve. Choice A is incorrect. Buccinator is a muscle of facial expression, derived from the third pharyngeal arch. It is supplied by CN VII. Masseter is supplied by V3. Choice B is incorrect. Mylohyoid is supplied by V3. Geniohyoid is supplied by a branch of cervical nerve IX which also supplies thyrohoid. Choice D is incorrect. The tensor veli palatini is supplied by V3. Levator palati is supplied by a motor branch of pharyngeal plexus, which is derived from CN X and the cranial portion of CN XI. Choice E is incorrect. Anterior belly of digastric is supplied by V3. Posterior belly is supplied by CN VII

Front 849

The unpaired vessels contributing to the arterial circle of the brain include the1. internal carotid and vertebral arteries.2. posterior and anterior cerebral arteries.3. anterior cerebral and anterior communicating arteries.4. anterior cerebral and posterior communicating arteries.5. anterior communicating and basilar arteries

Back 849

The correct answer is choice 5, the anterior communicating and basilar arteries...... The arterial circle of the brain, also known as the circle of Willis, is formed by the carotid and vertebral arteries anastomosing with each other on the ventral surface of the brain stem. It consists of seven vessels: a pair of anterior cerebral arteries, a branch of the anterior communicating artery unpaired, a pair of posterior communicating branches and a pair of posterior cerebral arteries. It also receives contribution from the basilar artery which is unpaired. Therefore, the unpaired vessels that contribute to the circle of Willis include the anterior communicating artery and the basilar artery choice 5. Choice 1, the internal carotid and vertebral arteries are both paired. Choice 2, the posterior and anterior cerebral arteries are both paired. Choice 3, the anterior cerebral arteries are paired and the anterior communicating artery is single and unpaired. Choice 4, the anterior cerebral and posterior communicating arteries are both paired. So the correct answer to question is choice 5.

Front 850

The vagus nerve supplies parasympathetic fibers to which of the following?A. Descending colonB. Ascending colonC. Sigmoid colonD. RectumE. Anus

Back 850

The correct answer is choice B, the ascending colon...... The ascending colon is part of the midgut, which extends from the hepatic diverticulum to the junction of the proximal two-thirds and distal one-third of the transverse colon. All structures derived from midgut and foregut receive preganglionic parasympathetic innervation from the vagus. Choice A is incorrect. The descending colon is derived from embryonic hindgut. which receives preganglionic parasympathetic innervation from pelvic splanchnic nerves (S2, S3, and S4). Choice B is incorrect. Sigmoid colon is derived from embryonic hindgut. Choice C is incorrect. The upper part of the rectum is derived from hindgut. The lower portion is derived from the embryonic cloaca1 region. Choice E is incorrect. The anus is innervated by the inferior rectal branch of the pudendal nerve. This is a somatic nerve.

Front 851

The vertebral artery is a branch of theA. brachiocephalic artery.B. external carotid artery.C. internal carotid artery.D. subclavian artery.E. thyrocervical trunk.

Back 851

The correct answer is choice D, the subclavian artery...... The vertebral artery is the largest branch of the first portion of the subclavian artery. It enters foramen magnum to supply the brainstem. Choice A is incorrect. The brachiocephalic artery (trunk) normally has no branches other than its terminal branches, the right subclavian and the right common carotid arteries. Choice B is incorrect. The external carotid artery has branches which supply structures of the neck and face. Choice C is incorrect. The internal carotid artery has no branches in the neck. Choice E is incorrect. The thyrocervical trunk is a branch of the subclavian artery which supplies the thyroid gland and structures of the neck and shoulder regions.

Front 852

The visceral and parietal pericardia are continuous at the1. pulmonary artery only.2. inferior vena cava only.3. veins and arteries entering and leaving the heart.

Back 852

The correct answer is choice 3, the veins and arteries entering and leaving the heart...... The pericardium is a fibroserous sac surrounding the heart and the beginning of the great vessels. It consists of a strong outer fibrous layer and a relatively thin inner serous layer. This serous layer is again subdivided into two layers, the visceral on the heart and the parietal on the fibrous portion of the pericardium. These layers are continuous with one another along a line running from the inferior vena cava, right pulmonary veins, superior vena cava and left pulmonary veins at one end and the aorta and pulmonary trunk at the other end. So the correct answer to question is choice 3.

Front 853

The white pulp of the spleen is composed primarily of1. sinusoids.2. macrophages.3. lymphocytes.4. connective tissue.

Back 853

The correct answer is choice 3, lymphocytes...... The spleen is a large lymphoid organ responsible for the removal of particulate matter from circulating blood, production of immunological responses against blood-borne antigens and removal of aged or defective blood cells from the circulation. Structurally, the spleen is composed of an outer capsule surrounding lymphoid tissues, known as the white pulp separated by blood-filled sinuses known as the red pulp. The white pulp is composed primarily of lymphocytes, choice 3. So the correct answer to question is choice 3.

Front 854

The zona glomerulosa of the adrenal cortex produces which of the following?A. AldosteroneB. CortisolC. EpinephrineD. ProgesteroneE. Somatostatin

Back 854

The correct answer is A, aldosterone........ The adrenal cortex is composed of three relatively distinct layers: zona glomerulosa, zona fasciculata, and zona reticularis. The zona glomerulosa of the adrenal cortex secretes aldosterone (choice A). The zona fasciculata and zona reticularis secrete cortisol (choice B) and several other glucocorticoids. Epinephrine (choice C) is produced by the adrenal medulla. Progesterone (choice D) is secreted by the corpus luteum of the ovaries and somatostatin (choice E) is produced by the pancreas

Front 855

The zona pellucida is associated with which of the following?1. Corpus luteum2. Corpus albicans3. Oocyte in a mature follicle4. Oocyte in an early primary follicle

Back 855

The correct answer is choice 3, an oocyte in a mature follicle....... With the onset of puberty, a number of primordial follicles begin to mature with each ovarian cycle. The ovocyte is an early primary follicle, choice 4. It undergoes several important changes as it matures. It begins to increase in size. The surrounding epithelial cells, the follicle cells, change from flat to cuboidal and a layer of acellular material is deposited on the surface of the ovocyte. This material which is produced by the follicular cells as well as the oocyte gradually increases in thickness forming the zona pellucida present in a mature follicle of the oocyte, choice 3. The corpus luteum, choice 1, is formed by the luteal cells following ovulation and secretes progesterone. The corpus albicans, choice 2, is a mass of fibrotic scar tissue and it is formed by the degeneration of the corpus luteum when fertilization fails to occur. So the correct answer to question is choice 3.

Front 856

The zona reticularis is the inner layer of the1. cortex of the thymus.2. medulla of the thymus.3. cortex of the suprarenal (adrenal).4. medulla of the suprarenal (adrenal).

Back 856

The correct answer is choice 3, cortex of the suprarenal (adrenal)....... The zona reticularis is the innermost layer of the cortex portion of the suprarenal glands, choice 3. The suprarenal glands are a pair of small yellowish brown bodies lying on the medial pan of the superior end of each kidney. The suprarenal glands are also known as the adrenal glands. These glands are essential for the secretion of imponant hormones including aldosterone. cortisone, adrenaline, and noradrenaline. Each gland is divided into two distinct parts, an outer cortex and an inner medulla. The outer cortex is further subdivided into three layers, the zona glomerularosa, the zona fasiculata and the zona reticularis, with the zona reticularis as the innermost layer. So the correct answer to question is choice 3.

Front 857

Tropocollagen is a protein molecule found in1. collagen and elastic fibers only.2. elastic and reticular fibers only.3. collagen and reticular fibers only.4. collagen, elastic and reticular fibers.

Back 857

The correct answer is choice 3, collage and reticular fibers....... Tropocollagen is the name for the 3-polypeptide chain molecule often referred to just as collagen. Collagen is found of course, in collagen fibers. It is also found in reticular fibers. However, collagen is not found in elastic fibers. Elastic fibers are composed of the protein elastin which is notable for the presence of amino acids, desmosine and isodesmosine. By contrast, collagen contains the unusual amino acids, hydroxyproline and hydroxylysine. So the correct answer to question is choice 3.

Front 858

Uniform growth in the infolding portion of an epithelial root sheath (Hertwig) results in formation of a1. single-rooted tooth.2. double-rooted tooth.3. three-rooted tooth.4. tooth without a root.

Back 858

The correct answer is choice 1, single rooted tooth..... Hertwig's epithelial root sheath formed by the enamel organ molds the shape of the roots. Prior to the beginning of root formation, the root sheath forms the epithelial diaphragm. Uniform growth in the infolding portion of the sheath, the epithelial diaphragm, will result in the formation of a single rooted tooth, choice 1. Invaginations along with differential growth of the epithelial diaphragm will result in a multirooted tooth, choices 2 and 3. Malformation or the absence of the Hertwig's epithelial root sheath can result in a tooth without a root, choice 4. So the correct answer to question is choice 1.

Front 859

Variation of the size of the lumen of the bronchiole during inspiration and expiration is caused primarily by1. striated muscle and cartilage.2. smooth muscle and elastic fibers.3. the basement membrane and collagen fibers.4. areolar connective tissue and cartilage.

Back 859

The correct answer is choice 2, smooth muscle and elastic fibers...... Respiratory bronchioles, the smallest units of the bronchopulmonary system, are short, smooth muscle tubes without cartilage. During inspiration and expiration, the bronchiole expands and contracts with its smooth muscle walls and supporting reticular a d elastic fibers. The other answer choices are incorrect because they contain cartilage or striated muscle. both of which are not contained in the bronchiole. Choice 3 is incorrect because the basement membrane and collagen fibers would not be able to vary in size since they cannot contract. So the correct answer to question is choice 2.

Front 860

What layer of the epidermis is composed of multilaminar cuboidal-like cells that are bound together by means of numerous cytoplasmic extensions and desmosomal junctions?A. Stratum basaleB. Stratum corneumC. Stratum granulosumD. Stratum lucidumE. Stratum spinosum

Back 860

The correct answer is E, the stratum spinosum...... The epidermis is the outermost layer of the integument. The layers of the epidermis from deep to superficial can be remembered with the following mnemonic: BiG Stars Give Lots of Charity; Stratum Basale (Germinativum), Spinosum, Granulosum, Lucidum, Corneum. The stratum spinosum (choice E) is a layer of the epidermis composed of multilaminar cuboidal-like cells that are bound together by means of numerous cytoplasmic extensions and desmosomal junctions. The stratum basale (choice A) is a proliferative basal layer of columnar-like cells that contain the fibrous protein keratin. The stratum corneum (choice B) is the outermost layer of the epidermis. This layer consists of many layers of flat, anucleated and keratinized cells. The stratum granulosum (choice C) consists of flat polygonal cells filled with basophilic keratohyalin granules. The stratum lucidum is a thin layer of cells located between the stratum granulosum and stratum corneum.

Front 861

When a tooth first erupts into the oral cavity, the attachment epithelium is derived from1. oral mucosa.2. reduced enamel epithelium.3. epithelial rests of Malassez.4. the epithelial root sheath (Hertwig).

Back 861

The correct answer is choice 2, reduced enamel epithelium..... When the cusps of the tooth emerge from the gingiva, the reduced enamel epithelium fuses with the gingival epithelium and, together with the primary cuticle or last cell layer of enamel, forms the epithelial attachment. The reduced enamel epithelium is tbe name for the combination of ameloblasts, stellate reticulum and outer enamel epithelium which remain after tooth formation is complete. Choice 3 is incorrect. The epithelial rests of Malassez are epithelial remnants of the epithelial sheath of Hertwig, choice 4. This sheath causes differentiation of odontoblasts to form root dentin and is composed of both inner and outer enamel epithelium. So the correct answer to question is choice 2.

Front 862

Which group of fibers of the periodontal ligament is the first to offer resistance to movement of the tooth in an occlusal direction?A. Alveolar crestB. lnterradicularC. HorizontalD. ObliqueE. Apical

Back 862

The correct answer is choice E, apical fibers...... From the coronal down to the apical, the periodontal fiber groups are: the alveolar crest fibers, slanted upward and coronally from alveolar crest to CEJ, then horizontal fibers from cementum horizontally to alveolar bone, then oblique fibers slanting downward and apically from alveolar bone to cementum, then apical fibers, connecting vertically from the apical part of the bony socket to the apex of the root. Because of their vertical position and attachment at the base of the root, these fibers are the first to resist an upward (occlusal, coronal) motion of the tooth. The correct answer to question is choice E.

Front 863

Which of the following are mobilized when a cell produces an excessive amount of protein?1. Lysosomes2. Mitochondria3. Lipofuscin granules4. Rough endoplasmic reticula5. All of the above

Back 863

The correct answer is choice 1, lysosomes....... Apparently, the question is referring to the method by which a cell can rid itself of excessive protein that it has produced. In this case, choice 1 is the logical answer, as lysosomes contain proteolytic enzymes capable of digesting cellular proteins. Choice 4 may come to mind because the proteins are produced by ribosomes of the rough endoplasmic reticulum. However, the question is referring to what occurs after these proteins are made. Choice 2 is incorrect because mitochondria produce ATPs from the oxidation of glucose. Choice 3 is incorrect. Lipofuscin granules refers to a fatty proteinaceous material that accumulates in older cells as a result of the action of lysosomes on cell materials. So the correct answer to question is choice 1.

Front 864

Which of the following are pure serous glands?A. Sublingual glandsB. Glands of BrunnerC. Submandibular glandsD. Glands of von EbnerE. Glands of Blandin-Nuhn

Back 864

The correct answer is choice D, glands of von ebner....... Lets review the serous/mucous content of the salivary glands. The largest gland, the parotid, is primarily, but not wholly, serous. (In infants, some mucous secretion is produced). Both the submandibular and sublingual are mixed serous/mucous, although the submandibular is primarily serous while the sublingual is primarily mucous. On the tongue, Von Ebner's glands are found in the area surrounding the vallate papillae. These glands are serous only. Other lingual glands are known as anterior lingual or Blandin-Nuhn glands. They are mixed, but primarily mucus. Labial and buccal glands are usually mixed glands. Brunners glands are found in the villi of the small intestine. So our correct answer to question is choice D.

Front 865

Which of the following arteries does NOT accompany the corresponding nerve throughout its course?1. Lingual2. lnfraorbital3. Inferior alveolar4. Posterior superior alveolar

Back 865

The correct answer is choice 1, the lingual artery...... The lingual artery is the main source of blood to the tongue and is a branch of the external carotid. The innervation of the tongue is supplied by the lingual branch of the mandibular nerve of the trigeminal for sensation to the anterior two-thirds; the chorda tympani, a branch of cranial nerve 7, for taste to the anterior two-thirds: the lingual branch of the glossopharyngeal nerve, cranial nerve 9, to the posterior one-third; and the superior laryngeal nerve of the vagus to the circumvallate papillae. None of these nerves travels completely with the lingual artery. Choice 2 is incorrect. The infraorbital nerve and artery travel together through the infraorbital foramen to the face below the orbit and to the anterior maxillary teeth. Choice 3 is incorrect. The inferior alveolar nerve and artery travel through the mandibular canal together to the mandibular teeth. The inferior alveolar artery is a branch of the maxillary artery. The posterior superior alveolar nerve and artery also travel together and the artery is also a branch of the maxillary artery. This artery and nerve supply the maxillary molar teeth. So the correct answer to question is choice 1.

Front 866

Which of the following arteries is NOT a branch of the maxillary artery?1. Deep temporal2. Middle meningeal3. Inferior alveolar4. Superficial temporal5. Posterior superior alveolar

Back 866

The correct answer is choice 4, the superficial temporal..... The maxillary artery, the terminal branch of the external carotid, gives off many branches. These include the deep temporal, choice 1, the middle meningeal, choice 2, the inferior alveolar, choice 3, and the posterior superior alveolar, choice 5. Only the superficial temporal, choice 4, is not a branch of the maxillary artery. It is actually a terminal branch of the external carotid. So the correct answer to question is choice 4.

Front 867

Which of the following BEST characterizes the alveolar mucous membrane?A. Has no melanocytesB. Firmly bound to underlying boneC. Well developed epithelial ridgesD. Separated from the gingiva by the free gingival grooveE. Appears red due to high vascularity and thinness of epithelium

Back 867

The correct answer is choice E, appears red due to high vascularity and thinness of epithelium.... Alveolar mucosa is a loosely bound non-keratinized epithelium of stratified epithelium above a lamina propria, with a submucosal layer. This is unlike the gingiva and epithelial tissue covering the hard palate, whih is tightly bound, keratinized and does not possess a submucosal layer. Melanocytes can be present in alveolar mucous membrane, and many dark-skinned people have darkly pigmented gingiva and oral mucosa. Well developed epithelial ridges are not found in alveolar mucous membrane. The gingiva is separated from the alveolar mucosa by the mucogingival junction. The free gingival groove marks the end of free gingiva, and the beginning of the attached gingiva. So, choices A,B,C, and D are all incorrect. Choice E is correct. Thin, non keratinized epithelium overlying a rich blood supply will appear red. Our correct answer to question is choice E.

Front 868

Which of the following BEST describes the passage of material through the hepatic sinusoids?A. Blood passes toward the central vein.B. Bile passes peripherally toward the portal canal.C. Lymph moves centrally to join the sublobular duct.D. Lymph moves peripherally toward the space of Disse.E. Blood passes peripherally away from the central vein.

Back 868

The correct answer is choice A. Blood from branches of the portal vein(nutrient rich) and hepatic artery(O2 rich) enters the liver sinusoids at the periphery of the liver lobule, and passes centripetally to reach the central vein. Choice B is incorrect. Bile is excreted by hepatocytes into radicles of the bile duct system. Choice C is incorrect. Lymphatic vessels of the liver lead to larger vesssels in the pona hepatis and enter hepatic nodes. Choice D is incorrect. The space of Disse separates the hepatocyte from the sinusoidal vessel. It is not a lymphatic channel. Choice E is incorrect. Blood passes centripetally towards the central vein of the liver lobule.

Front 869

Which of the following blood elements is a fragment of megakaryocytic cytoplasm?1. Platelet2. Normoblast3. Erythrocyte4. Promyelocyte5. Proerythroblast

Back 869

The correct answer is choice 1. Platelets are formed in the red bone marrow and to a small extent in the spleen by fragmentation of very large cells known as megakaryocytes. These megakaryocytes have large multilobed nuclei of varied shapes. Choice 2, normoblast, is incorrect. Normoblasts are a precursor stage of erythrocytes or red blood cells. Choice 3 is incorrect. Erythrocytes or red blood cells form by erythropoiesis in the red bone marrow from nucleated cells known as hemocytoblasts or stem cells. Choice 4 is incorrect. Promyelocytes are precursor cells of the granulocytes: the neutrophils, basophils and eosinophils. Choice 5 is incorrect. A proerythroblast is another precursor cell of erythrocytes or red blood cells. So the correct answer to question is choice 1.

Front 870

Which of the following branches of the axillary artery usually supplies the latissimus dorsi muscle?1. Thoracodorsal2. Thoracoacromial3. Lateral thoracic4. Circumflex scapular5. Posterior humeral circumflex

Back 870

The correct answer is choice 1. The latissimus dorsi muscle is a very broad, flat triangular muscle in the lower part of the back which is overlapped by the lower part of the trapezius muscle. It is innervated by the thoracodorsal nerve, a branch of the brachial plexus. The blood is supplied by the thoracodorsal artery, choice 1, a branch of the subscapular from the axillary artery. The thoracoacromial artery, choice 2, a branch of the axillary artery gives off branches that supply the deltoid, pectoralis major and minor and the subclavius muscles. The lateral thoracic, choice 3, also a branch of the axillary artery, primarily supplies the mammary glands. The circumflex scapular artery, choice 4, a branch of the subscapular off the axillary artery, curves around the scapular and anastomoses with the suprascapular and dorsal scapular aneries. The posterior humeral circumflex artery, choice 5, branches off the lower part of the axillary artery and anastomoses with the anterior humeral circumflex artery, also a branch of the axillary artery. So the correct answer to question is choice 1.

Front 871

Which of the following cells is most likely to have an abundant amount of rough-surfaced endoplasmic reticulum?1. Osteocyte2. Macrophage3. Osteoblast4. Mesothelial cell5. Small lymphocyte

Back 871

The correct answer is choice 3. This is really an indirect question about the function of cell organelles. Rough-surfaced endoplasmic reticulum produces proteins for export out of the cell. The rough surface is lined with ribosomes which produce proteins. Choice 1, osteocytes, are mature bone cells living within already-formed bone and do not produce large quantities of protein for export. Choice 2, macrophages, are primarily involved in ingesting foreign material and are involved in immune respose. They do not produce large quantities of export protein. Choice 3, osteoblasts, is correct. Osteoblasts are bone-forming cells which lay down bone matrix which is primarily protein. Choice 4, mesothelial cells, are lining cells inside blood vessels. They do not produce large amounts of export protein. Choice 5, lymphocytes, is also incorrect. Lymphocytes, involved primarily in immune response, do not produce large quantities of export protein. It should be noted that if lymphocytes become plasma cells -- in particular, B lymphocytes when they differentiate into plasma cells -- then large quantities of antibodies would be produced. However, we're talking here about lymphocytes, so the correct answer to question is choice 3.

Front 872

Which of the following branches of the external carotid artery originates just below the level of the hyoid bone's greater cornu?1. The facial artery2. The occipital artery3. The maxillary artery4. The superior thyroid artery5. The posterior auricular artery

Back 872

The correct answer is choice 4. The external carotid anery extends from the upper border of the thyroid cartilage to the back of the neck of the mandible where it ends by dividing into the superficial temporal and maxillary artery. Eight branches arise from the external carotid artery. Only the superior thyroid artery, choice 4, originates just below the tip of the greater horn of the hyoid bone and runs downwards to the thyroid gland. The facial artery, choice 1 , arises immediately above the lingual and ends at the medial angle of the eye. Thc occipital artery, choice 2, originates opposite the facial artery and ends near the medial end of the occipital bone. The maxillary artery, choice 3, beglns between the parotid gland and the back of the neck of the mandible and ends in the pterygopalatine fossa. The posterior auricular artery, choice 5, arises just above the posterior belly of the digastric and runs into the internal space between the mastoid process and the auricle. So the correct answer to question is choice 4.

Front 873

Which of the following cranial nerves contain parasympathetic preganglionic fibers?A. II, III, IV, and VB. III, IV, V, and VIC. III, V, VII, and IXD. III, VII, IX, and XE. VII, IX, X, and XI

Back 873

The correct answer is choice D. CN's III, VII, IX and X are the only cranial nerves which contain preganglionic parasympathetic fibers, which synapse in the four parasympathetic ganglia of the head, or (in the case of CN X), in thoracic and abdominal nerve plexuses. Choice A is incorrect. Only CN III contains preganglionic parasympathetic fibers, which synapse in the ciliary ganglion. Choice B is incorrect. Only CN III contains preganglionic parasympathetic fibers. Choice C is incorrect. Although CN V distributes postganglionic fibers which have synapsed in the four parasympathetic ganglia of the head (ciliary, pterygopalatine, submandibular and otic), it is not considered a parasympathetic nerve because it contains no preganglionic fibers. Choice E is incorrect. CN XI, the spinal accessory, is a motor nerve which supplies trapezius and sternocleidomastoid.

Front 874

Which of the following empty into the right atrium?1. The pulmonary and bronchial veins2. The coronary sinus and pulmonary veins3. The superior and inferior venae cavae and coronary sinus4. The superior vena cava, coronary sinus, and hemiazygos vein

Back 874

The correct answer is choice 3. The heart is divided into right and left sides, each of which is composed of two chambers, an atrium and a ventricle. The right atrium has the thinnest walls of the four chambers. It receives deoxygenated blood from the superior vena cava, inferior vena cava, coronary sinus and anterior cardiac veins. This corresponds to answer choice 3. So the correct answer to question is choice 3.

Front 875

Which of the following explains why the Barr body found in certain epithelial cells is significant?A. It suggests mitotic activity.B. It indicates protein synthesis.C. It indicates a metaplasmic change.D. It is a symptom of nuclear disintegration.E. It assists in differentiating between the sexes.

Back 875

The correct answer is choice E. The Barr body is useful in determining the sex of a cell. In certain epithelial cells, the presence of the Barr body indicates a female cell, while its absence indicates a male cell. During interphase, one X chromosome remains condensed as a dark staining body near the nuclear membrane. One X chromosome does not take this form. Since only the female has two X chromosomes, only the female can have a Barr body. The Barr body can be used in identifying the genetic sex of an individual, and has been used, for example, in the Olympics, to ensure the accurate sex of the participants. The correct answer to question is choice E.

Front 876

Which of the following features distinguishes bone from osteoid?A. Bone is not resorbed.B. Bone has a mineralized matrix.C. Osteoid contains fewer lacunae per unit area.D. Osteoid contains a different type of fiber in its matrix.

Back 876

The correct answer is choice B. Osteoid is uncalcified bone matrix. Small temporary areas of osteoid are part of the normal bone-forming process. Large abnormal areas may be present in diseases such as rickets. Osteoid contains matrix fibers but no calcium phosphate mineral salts. Looking at the other choices, A is incorrect because mature bone is constantly resorbed and remodeled by osteoclasts and osteoblasts. C is incorrect because the number of lacunae, with trapped osteocytes, is determined once the unmineralized matrix is set down, so that bone and osteoid have the same number of lacunae. D is incorrect as the only change that occurs to osteoid matrix is mineralization. No fiber change occurs. So the correct answer to question is choice B.

Front 877

Which of the following forms of connective tissues has a preponderance of amorphous ground substance over fibers?1. Loose2. Cartilage3. Reticular4. Dense, regularly arranged5. Dense, irregularly arranged

Back 877

The correct answer is choice 2. Connective tissue usually contains fibers, often of collagen, and ground substance which is an amorphous material surrounding the fibers. In particular, loose connective tissue (choice 1) is stretchable and contains collagenous and elastic fibers and hyaluronic acid ground substance. Choice 2, cartilage, our correct choice, contains fibers of collagen or elastic, but a much greater percentage of ground substance than found in the other connective tissues. Choice 3, reticular connective tissue, is primarily fibrous; in particular, reticular fibers. It is found in lymph nodes and spleen and does not contain much ground substance. Dense connective tissues, choices 4 and 5, consist primarily of collagenous or elastic fiber bundles with only smaller amounts of fluid matrix. Dense connective tissue comprises tendons and ligaments. So the correct answer to question is choice 2.

Front 878

Which of the following glands stimulates osteoclast activity?A. Anterior pituitaryB. HypothalamusC. PancreasD. ParathyroidE. Thyroid

Back 878

The correct answer is D. Osteoclasts are large, motile multinucleated cells found on bone surfaces at sites of resorption. When stimulated by parathyroid hormone produced in the parathyroid gland (choice D), osteoclasts increase blood calcium levels by the resorption of bone tissue. The anterior pituitary (choice A) produces various hormones, such as growth hormone, prolactin, adrenocorticotropin hormone, thyroid stimulating hormone, luteinizing hormone and follicle stimulating hormone, all of which do not affect blood calcium levels. The hypothalamus (choice B) produces hormones that lead to increased uterine contraction and water reabsorption in the kidney. The pancreas (choice C) is primarily involved with regulating blood glucose levels. The thyroid (choice E) produces calcitonin which lowers blood calcium levels.

Front 879

Which of the following groups of periodontal ligament fibers has a cementum-to cementum attachment?1. Oblique2. Transseptal3. Free gingival4. lnterradicular5. Dentoalveolar crest

Back 879

The correct answer is choice 2. Transseptal fibers are fibers of the periodontal ligament which extend from the cementum of one tooth above the alveolar crest to the cementum of an adjacent tooth. Oblique fibers, choice 1, extend from cementum to alveolar a bone as do dental alveolar fibers, choice 5. Free gingival fibers (choice 3) attach to the tooth cementum and extend out into the gingival tissue. Choice 4, interradicular fibers, connect from cementum to bone in multi-rooted teeth. So the correct answer to question is choice 2.

Front 880

Which of the following is derived from ectomesenchyme?A. AmeloblastsB. OdontoblastsC. Stellate reticulumD. Stratum intermediumE. Reduced enamel epithelium

Back 880

The correct answer is choice B. This is a case of "one of these things is not like the others". Note that all of the choices except B are related to enamel formation, and enamel is derived from ectodermal tissue of neural crest origin. Only odontoblasts, which form dentin, are not from this origin. Odontoblasts, as well as the pulp and the dental papilla from which they form, are of mesenchymal(and therefore mesodermal) origin. Don't be fooled by the "ecto" in ectomesenchyme. Mesenchyme is still mesodermal tissue. The correct answer to question is choice B.

Front 881

Which of the following is located at the opening between the small and the large intestines?1. The cardiac sphincter2. The pyloric sphincter3. The ileocecal valve4. The tricuspid valve

Back 881

The correct answer is choice 3. The cardiac sphincter, choice 1, is located between the inferior end of the esophagus and the stomach. The smooth muscle of this junction is continuous with that of the stomach and the muscle is not considered a true structural sphincter. The pyloric sphincter, choice 2, is located between the pyloric end of the stomach and the duodenum. While it does not control the rate of stomach emptying, it does however control the size of the particle that enters the duodenum. The ileocecal valve, choice 3, guards the opening into the cecum, the anterior portion of the large intestine, from the ileum, the posterior portion of the small intestine. It functions as an impediment to regurgitation of the cecal contents into the ileum. The tricuspid valve, choice 4, transmits blood from the right atrium of the heart to the right ventricle. It also prevents regurgitation of blood back into the right atrium during ventricular systole. So the correct answer to question is choice 3.

Front 882

Which of the following is necessary for cementum to be deposited during tooth development?1. The tooth must be erupting.2. A bony socket must develop.3. An apical vascular plexus must be present.4. The continuity of the root sheath (Hertwig) must be broken.

Back 882

The correct answer is choice 4. Root development is begun by the Hertwig root sheath which consists of inner and outer enamel epithelium. This root sheath causes dental papilla tissue to differentiate into odontoblasts and then lay down root dentin. The root sheath is then broken down as connective tissue elements form the fibers of the periodontal ligament. The remaining cells of the dental sac will then form cementum and alveolar bone. The leftover root sheath cells will become epithelial rests of Mallasez. The cementum deposition does not depend on tooth eruption (choice 1) or bony socket development (choice 2) or the presence of a vascular plexus at the root apex (choice 3). So the correct answer to question is choice 4.

Front 883

Which of the following is surrounded partly by connective tissue and epithelium, contains lymphoid follicles, has no sinuses, and is penetrated by a number of crypts?A. SpleenB. ThymusC. Lymph nodeD. Palatine tonsilE. Bursa of Fabricius

Back 883

The correct answer is choice D. The palatine tonsil is a lymphoid organ which forms a ring in the pharynx, between the glossopalatine and pharyngopalatine arches. It consists of blind sacs, or crypts which are composed of epithelial tissue overlying thin connective tissue. They may contain lymphocytes and polymorphonucleocytes. Their exact protective function is not known, but the tonsils are protective against microorganisms. The spleen has lymphoid follicles, as well as sinuses(in the red pulp), but does not contain crypts. The thymus also contains lymphoid follicles, with great numbers of lymphocytes surrounded by conective tissue, but lacks crypts. The lymph node contains filtering lymph sinuses with macrophages and reticular cells, but does not contain crypts. The Bursa of Fabricius is an organ in birds where B lymphocytes become specialized. It does not exist in humans. So the correct answer to question is choice D.

Front 884

Which of the following layers is totally lacking in thin skin?1. Stratum corneum2. Stratum lucidum3. Stratum spinosum4. Stratum germinativum

Back 884

The correct answer is choice 2. The skin, or integument, is the largest organ of the body constituting almost one sixth of the total body weight. Its functions include protection, sensation, and thermal regulation. Structurally, the skin is divided into a deep layer, the dermis, and a superficial layer, the epidermis. The epidermis is made up of five layers of cells in thick skin and four layers of cells in thin skin. From superficial to deep, thick skin consists of firstly, the stratum corneum on the surface, then the stratum lucidum, the stratum granulosum, the stratus spinosum and the stratum germinativum. In thin skin, however, the stratum lucidum, choice 2, is not present. So the correct answer to question is choice 2.

Front 885

Which of the following layers of the epidermis is least cytodifferentiated1. Stratum basale2. Stratum corneum3. Stratum spinosum4. Prickle-cell layer5. Stratum granulosum

Back 885

The correct answer is choice 1. Let's review the layers of the epidermis. Stratum basale, choice 1, is the deepest layer and consists of a single layer of columnar cells. This layer and the stratum spinosum, choice 3, above it produce the replacement cells for all other epidermal layers. However, the stratum spinosum layer cells are more flat and more differentiated than. the stratum basale. Choice 5, stratum granulosum, is above the stratum spinosum and the cells in this layer contain keratohyalin and they are more flattened. Stratum corneum, choice 2, contains the dead, flattened keratinized surface cells which flake off to the outside. Choice 4, a prickle cell layer, refers to the stratum spinosum, choice 3, and describes the appearance of the cells in the stratum spinosum. So the correct answer to question is choice 1.

Front 886

Which of the following ligaments of the temporomandibular joint is attached to the circumference of the mandibular fossa, the articular tubercle, and to the neck of the condyle of the mandible?A. Articular CapsuleB. Articular DiskC. LateralD. SphenomandibularE. Stylomandibular

Back 886

The correct answer is A. The articular capsule (choice A) of the temporomandibular joint is attached to the circumference of the mandibular fossa and the articular tubercle, and to the neck of the condyle of the mandible. The articular disk (choice B) is located between the condyle of the mandible and mandibular fossa. The lateral ligament (choice C) is attached to the lateral surface of the zygomatic arch and to the tubercle on its inferior border superiorly. It is also connected to the lateral surface and posterior border of the neck of the mandible inferiorly. The sphenomandibular ligament (choice D) is attached to the spine of the sphenoid bone and to the lingula of the mandibular foramen. The stylomandibular ligament (choice E) extends from the apex of the styloid process of the temporal bone to the ramus of the mandible between the Masseter and Pterygoideus medialis (medial pterygoid).

Front 887

Which of the following may cause dead tracts in dentin?1. Caries2. Erosion3. Cavity preparation4. Odontoblastic crowding5. Any of the above

Back 887

The correct answer is choice 5. Dark areas in dentinal tubules viewed under the light microscope are known as dead tracts. They are believed to be dead or coagulated cytoplasmic processes of odontoblasts or degenerated contents of the tubules. Common causes of dead tracts are any acute aggravations of the cytoplasmic processes of the odontoblasts. These would include caries, erosion and cavity preparation. Since the dead tracts are also found in unerupted and intact mature teeth, they have other nonpathological causes including crowding of the odontoblasts. So actually all four answers are correct, and the correct answer to question #1 is choice 5

Front 888

Which of the following muscles insert(s) onto the neck of the condyle?A. MasseterB. TemporalisC. Lateral pterygoidD. Medial pterygoid

Back 888

The correct answer is choice C. The lateral pterygoid inserts (in part) onto the fovea of the neck of the condyle. Choice A is incorrect. The masseter inserts along the lateral surface of the mandibular ramus. Choice B is incorrect. The temporalis inserts on the coronoid process of the mandible. Choice D is incorrect. The medial pterygoid inserts on the medial surface of the mandibular ramus, below the mandibular foramen.

Front 889

Which of the following muscles receives its motor supply from the facial nerve?1. Masseter2. Temporal3. Buccinator4. Lateral pterygoid5. Tensor veli palatini

Back 889

he correct answer is choice 3. Let's review the choices. The masseter and temporalis (choices 1 and 2) are muscles of mastication and act primarily as closing or elevating muscles. They receive their innervation from cranial nerve 5; in particular, from motor efferents in the anterior division of the mandibular nerve or V3. Choice 4, the lateral pterygoid, is also a muscle of mastication and it generally depresses, opens or protrudes the mandible. It also receives innervation from the anterior division of the mandibular nerve. Choice 5, tensor veli palatini, tightens the soft palate and is also innervated by the anterior division of the mandibular nerve, in particular, by the branch to the medial pterygoid. This leaves the buccinator muscle which makes up the bulk of the cheek and is innervated by cranial nerve 7, the facial nerve; in particular, the buccal branches. So the correct answer to question is choice 3.

Front 890

Which of the following muscles serve to raise the soft palate during swallowing?A. Levator veli palatiniB. PalatopharyngeusC. PalatoglossusD. SalpingopharyngeusE. Tensor veli palatini

Back 890

The correct answer is A. Movement of the soft palate occurs in the following manner: The soft palate is raised by the contraction of the levator veli palatini (choice A). At the same time that the soft palate is being raised, the superior constrictor muscle contracts to pull the posterior pharyngeal wall forward. The palatopharyngeus muscle (choice B) also contracts to pull the palatopharyngeal arches medially. This results in the nasal part of the pharynx being closed off from the oral part. The palatoglossus muscle (choice C) pulls the root of the tongue upward and backward. The salpingopharyngeus (choice D) serves to elevate the larynx and pharynx during the act of swallowing. The tensor veli palatini (choice E) muscles move the soft palate downward.

Front 891

Which of the following muscles serves as the forearm's principal extensor?1. Pronator teres2. Brachioradialis3. Triceps brachii4. Coracobrachialis5. Extensor carpi radialis longus

Back 891

The correct answer is choice 3. The principal extensor of the forearm is the triceps brachii, choice 3. Its main action is to extend the forearm because its direction of pull is posterior to the axis of the elbow joint. The pronator teres, choice 1, acts to pronate the hand and flex the forearm. Brachioradialis, choice 2, acts to initiate supination and pronation and to flex the forearm. Coracobrachialis, choice 4, acts primarily to flex the arm and abduct it. Extensor carpi radialis longus, choice 5, acts to extend and abduct the hand. So the correct answer to question is choice 3.

Front 892

Which of the following nerves contributes to the motor innervation of intrinsic muscles of the tongue?A. V3B. VIIC. IXD. XII

Back 892

The correct answer is choice D. The hypoglossal nerve provides innervation to all intrinsic and extrinsic muscles of the tongue except palatoglossus. Choice A is incorrect. The motor division of V3 supplies the four muscles of mastication, the tensor tympani and tensor veli palatini, and mylohyoid and anterior belly of digastric, all of which are derived from the first pharyngeal arch. Choice B is incorrect. CN VII supplies muscles derived from the second pharyngeal arch. Muscles of the tongue originate from occipital somites. Choice C is incorrect. CN IX, the nerve of the third arch, supplies only stylopharyngeus. It conveys sensory information, general and special (taste) from the posterior one-third of the tongue.

Front 893

Which of the following nerves innervate the upper canine and incisor teeth?A. Anterior superior alveolar nerveB. Middle superior alveolar nerveC. Posterior superior alveolar nerveD. Tympanic nerveE. Zygomatic nerve

Back 893

The correct answer is A. The maxillary nerve arises from the trigeminal ganglion located in the cranial fossa and branches into the anterior superior alveolar nerve, middle superior alveolar nerve, posterior superior alveolar nerve, and zygomatic nerve. It also has meningeal and ganglionic branches. The anterior superior alveolar nerve (choice A) innervates the upper canine and incisor teeth as well as the lateral wall and floor of the nose. The middle superior alveolar nerve (choice B) supplies the upper premolar teeth and the adjoining parts of the gum and cheek. The posterior superior alveolar nerve (choice C) supplies the maxillary sinus, upper molar teeth and the adjoining parts of the cheek and gingiva. There may be some overlap innervation of the maxillary teeth. The tympanic nerve (choice D) supplies the lining of the tympanic cavity and the zygomatic nerve (choice E) supplies the skin of the face.

Front 894

Which of the following nerves innervates the capsule of the temporomandibular joint?1. Facial2. Buccal3. Maxillary4. Mylohyoid5. Auriculotemporal

Back 894

The correct answer is choice 5. The temporal mandibular joint is a synovial joint formed by the condyle of the mandible articulating against the mandibular or glenoid fossa of the temporal bone. The innervation of the temporal mandibular joint including the joint capsule is provided mainly from the auriculotemporal branch of the mandibular division of the trigeminal nerve which is cranial nerve V. So the correct answer to question is choice 5.

Front 895

Which of the following nerves innervates the trapezius muscle?A. RadialB. AxillaryC. AccessoryD. ThoracodorsalE. Long thoracic

Back 895

The correct answer is choice C. The spinal accessory nerve (CN XI) originates from upper cervical spinal cord segments. A root is formed which ascends through foramen magnum to join the cranial portion of the nerve, which arises from the brainstem. The nerve exits the skull through the jugular foramen, and the spinal portion passes to the posterior triangle of the neck, where it supplies sternocleidomastoid and trapezius. Choice A is incorrect. The radial nerve arises from the posterior cord of the brachial plexus. It innervates extensor muscles of the arm and forearm. Choice B is incorrect. The axillary nerve is a terminal branch of the posterior cord of the brachial plexus. It supplies deltoid and teres minor. Choice D is incorrect. The thoracodorsal nerve is a branch of the posterior cord of the brachial plexus. Also known as the middle subscapular nerve, it supplies latissimus dorsi. Choice E is incorrect. The long thoracic nerve arises from the roots of the brachial plexus. It supplies serratus anterior.

Front 896

Which of the following nerves is the MOST likely to become injured in fractures of the mid-humeral shaft?A. UlnarB. RadialC. MedianD. AxillaryE. Musculocutaneous

Back 896

The correct answer is choice B. The radial nerve travels in the radial (spiral) groove on the posterior aspect of the midhumeral shaft. Choice A is incorrect. The ulnar nerve passes posterior to the medial epicondyle of the humerus at its most inferior aspect. Choice C is incorrect. The median nerve lies in the anterior compartment of the arm on the brachialis muscle. It is unlikely to be damaged by a midhumeral fracture. Choice D is incorrect. The axillary nerve passes from the axilla through the quadrangular space to reach deltoid and teres minor. It is subject to injury in fractures of the surgical neck of the humerus. Choice E is incorrect. The musculocutaneous nerve is never in direct contact with the humerus and is not likely to be injured in a humeral fracture.

Front 897

Which of the following papillae of the tongue are the largest, are the least numerous, have many taste buds, and are associated with the ducts of von Ebner's glands?1. Foliate2. Filiform3. Fungiform4. Circumvallate

Back 897

The correct answer is choice 4. The mucosa of the dorsal surface of the tongue has four different types of lingual papillae. Some of these have a mechanical function while others bear taste buds and have a sensory function. Choice 1, the foliate papillae, contain only a few taste buds and resemble sharp parallel clefts of varying lengths on the lateral tongue. Choice 2, the filiform papillae, cover the anterior portion of the tongue. These are cone shaped and contain no taste buds. Interspersed between the filiform papillae are the isolated fungiform papillae, choice 3. These are round and reddish and contain a few taste buds. Last, but not least, the circumvallate papillae, choice 4, are the largest type of lingual papillae. They are surrounded by a deep circular groove into which open the ducts of von Ebner's gland, which is a minor salivary gland. They are also the least numerous, usually consisting of 8-12 on the tongue, and they contain many tastebuds. So the correct answer to question is choice 4.

Front 898

Which of the following nerves innervate the upper canine and incisor teeth?A. Anterior superior alveolar nerveB. Middle superior alveolar nerveC. Posterior superior alveolar nerveD. Tympanic nerveE. Zygomatic nerve

Back 898

The correct answer is A. The maxillary nerve arises from the trigeminal ganglion located in the cranial fossa and branches into the anterior superior alveolar nerve, middle superior alveolar nerve, posterior superior alveolar nerve, and zygomatic nerve. It also has meningeal and ganglionic branches. The anterior superior alveolar nerve (choice A) innervates the upper canine and incisor teeth as well as the lateral wall and floor of the nose. The middle superior alveolar nerve (choice B) supplies the upper premolar teeth and the adjoining parts of the gum and cheek. The posterior superior alveolar nerve (choice C) supplies the maxillary sinus, upper molar teeth and the adjoining parts of the cheek and gingiva. There may be some overlap innervation of the maxillary teeth. The tympanic nerve (choice D) supplies the lining of the tympanic cavity and the zygomatic nerve (choice E) supplies the skin of the face.

Front 899

Which of the following represent fan-shaped, hypocalcified areas that originate at the dentinoenamel junction and extend into enamel for part of its thickness?A. TuftsB. SpindlesC. LamellaeD. Hunter-Schreger bandsE. Contour lines of Owen

Back 899

The correct answer is choice A. Tufts are hypocalcified enamel rods and less mineralized interprismatic organic substance extending from the DEJ into enamel. Enamel spindles are short dentinal tubules extending into enamel and ending blindly. Enamel lamellae are hypocalcified areas of enamel extending from the outer surface inward towards the dentin. They form between enamel prisms. Hunter-Schreger bands are regular lines seen in enamel as a result of changes in orientation of the enamel prisms. Contour lines of Owen are found in dentin, not enamel, and represent disturbances in the mineralization of incremental layers of dentin. The correct answer to question is choice A.

Front 900

Which of the following nerves innervates the capsule of the temporomandibular joint?1. Facial2. Buccal3. Maxillary4. Mylohyoid5. Auriculotemporal

Back 900

The correct answer is choice 5. The temporal mandibular joint is a synovial joint formed by the condyle of the mandible articulating against the mandibular or glenoid fossa of the temporal bone. The innervation of the temporal mandibular joint including the joint capsule is provided mainly from the auriculotemporal branch of the mandibular division of the trigeminal nerve which is cranial nerve V. So the correct answer to question is choice 5.

Front 901

Which of the following represents the cranial nerve that supplies derivatives of the third branchial arch?A. FacialB. AccessoryC. TrigeminalD. HypoglossalE. Glossopharyngeal

Back 901

The correct answer is choice E. The glossopharyngeal nerve is the nerve of the third pharyngeal (branchial) arch. The only muscle derived from the third arch is stylopharyngeus. Choice A is incorrect. The facial nerve is the nerve of the second arch. Choice B is incorrect. The spinal accessory innervates trapezius and sternocleidomastoid, neither of which originates from pharyngeal arches. Choice C is incorrect. CN V3 is the nerve of the first arch. Choice D is incorrect. The hypoglossal nerve is a somatic nerve which innervates muscles of the tongue.

Front 902

Which of the following nerves innervates the trapezius muscle?A. RadialB. AxillaryC. AccessoryD. ThoracodorsalE. Long thoracic

Back 902

The correct answer is choice C. The spinal accessory nerve (CN XI) originates from upper cervical spinal cord segments. A root is formed which ascends through foramen magnum to join the cranial portion of the nerve, which arises from the brainstem. The nerve exits the skull through the jugular foramen, and the spinal portion passes to the posterior triangle of the neck, where it supplies sternocleidomastoid and trapezius. Choice A is incorrect. The radial nerve arises from the posterior cord of the brachial plexus. It innervates extensor muscles of the arm and forearm. Choice B is incorrect. The axillary nerve is a terminal branch of the posterior cord of the brachial plexus. It supplies deltoid and teres minor. Choice D is incorrect. The thoracodorsal nerve is a branch of the posterior cord of the brachial plexus. Also known as the middle subscapular nerve, it supplies latissimus dorsi. Choice E is incorrect. The long thoracic nerve arises from the roots of the brachial plexus. It supplies serratus anterior.

Front 903

Which of the following represents the location of the cell bodies of pain fibers in the glossopharyngeal nerve?A. Otic ganglionB. Nucleus ambiguusC. Trigeminal (semilunar) ganglionD. Spinal nucleus of cranial nerve VE. Superior ganglion of cranial nerve IX

Back 903

The correct answer is choice E. Sensory cell bodies for fibers in CN IX are found in the superior or inferior ganglia of the nerve. Choice A is incorrect. The otic ganglion consists of postsynaptic cell bodies of parasympathetic fibers which supply the parotid gland. Choice B is incorrect. The nucleus ambiguus contains motor neurons for fibers of cranial nerves IX, X and XI. Choice C is incorrect. The trigeminal ganglion contains sensory cell bodies for nerve fibers of each of the divisions of CN V. Choice D is incorrect. The spinal nucleus of V contains secondary cell bodies in the pathway concerned with pain and other general sensation.

Front 904

Which of the following nerves is the MOST likely to become injured in fractures of the mid-humeral shaft?A. UlnarB. RadialC. MedianD. AxillaryE. Musculocutaneous

Back 904

The correct answer is choice B. The radial nerve travels in the radial (spiral) groove on the posterior aspect of the midhumeral shaft. Choice A is incorrect. The ulnar nerve passes posterior to the medial epicondyle of the humerus at its most inferior aspect. Choice C is incorrect. The median nerve lies in the anterior compartment of the arm on the brachialis muscle. It is unlikely to be damaged by a midhumeral fracture. Choice D is incorrect. The axillary nerve passes from the axilla through the quadrangular space to reach deltoid and teres minor. It is subject to injury in fractures of the surgical neck of the humerus. Choice E is incorrect. The musculocutaneous nerve is never in direct contact with the humerus and is not likely to be injured in a humeral fracture.

Front 905

Which of the following represents the main support of the wall of a bronchus?A. Smooth muscleB. Hyaline cartilageC. Elastic membranesD. Dense irregular connective tissueE. Elastic and collagenous connective tissue

Back 905

The correct answer is choice B. Cartilaginous rings surround the primary bronchi. Choice A is incorrect. Smooth muscle is the major component in the walls of bronchioles. Choice C is incorrect. Elastic fibers are present in all parts of the bronchial tree, but do not represent the major component in any. Choice D is incorrect. Dense, irregular connective tissue is not the major component of the primary bronchus. Choice E is incorrect. Elastic and collagenous connective tissue are present in primary bronchi and their branches, but are not the major components.

Front 906

Which of the following papillae of the tongue are the largest, are the least numerous, have many taste buds, and are associated with the ducts of von Ebner's glands?1. Foliate2. Filiform3. Fungiform4. Circumvallate

Back 906

The correct answer is choice 4. The mucosa of the dorsal surface of the tongue has four different types of lingual papillae. Some of these have a mechanical function while others bear taste buds and have a sensory function. Choice 1, the foliate papillae, contain only a few taste buds and resemble sharp parallel clefts of varying lengths on the lateral tongue. Choice 2, the filiform papillae, cover the anterior portion of the tongue. These are cone shaped and contain no taste buds. Interspersed between the filiform papillae are the isolated fungiform papillae, choice 3. These are round and reddish and contain a few taste buds. Last, but not least, the circumvallate papillae, choice 4, are the largest type of lingual papillae. They are surrounded by a deep circular groove into which open the ducts of von Ebner's gland, which is a minor salivary gland. They are also the least numerous, usually consisting of 8-12 on the tongue, and they contain many tastebuds. So the correct answer to question is choice 4.

Front 907

Which of the following represents the organelle that is typically composed of vesicles and of curved, flattened cisternae that are parallel to one another?1. Centriole2. Mitochondrion3. Golgi complex4. Rough endoplasmic reticulum5. Smooth endoplasmic reticulum

Back 907

The correct answer is choice 3. From the description given, the Golgi complex, choice 3, is the only possible response. The Golgi complex is primarily involved in the packaging of proteins and other secretory products into membrane-bound vesicles for exocytosis. Centrioles, choice 1, are structures involved in formation of the mitotic apparatus along which chromosomes migrate during mitosis. Their shape would resemble cylinders with microtubules inside. Mitochondria, choice 2, are elongated cigar-shaped organelles involved in ATP production. Rough endoplasmic reticulum, choice 4, consists of a network of tubules and flattened cisternae which are studded with ribosomes on the surface. Rough endoplasmic reticulum is mainly responsible for protein synthesis. Smooth endoplasmic reticulum. choice 5, consists of a network of tubules and vesicles. It plays an important role in lipid biosynthesis and it is thought to be part of the inuacellular transport system. So the correct answer to question is choice 3.

Front 908

Which of the following represent fan-shaped, hypocalcified areas that originate at the dentinoenamel junction and extend into enamel for part of its thickness?A. TuftsB. SpindlesC. LamellaeD. Hunter-Schreger bandsE. Contour lines of Owen

Back 908

The correct answer is choice A. Tufts are hypocalcified enamel rods and less mineralized interprismatic organic substance extending from the DEJ into enamel. Enamel spindles are short dentinal tubules extending into enamel and ending blindly. Enamel lamellae are hypocalcified areas of enamel extending from the outer surface inward towards the dentin. They form between enamel prisms. Hunter-Schreger bands are regular lines seen in enamel as a result of changes in orientation of the enamel prisms. Contour lines of Owen are found in dentin, not enamel, and represent disturbances in the mineralization of incremental layers of dentin. The correct answer to question is choice A.

Front 909

Which of the following represents the cranial nerve that supplies derivatives of the third branchial arch?A. FacialB. AccessoryC. TrigeminalD. HypoglossalE. Glossopharyngeal

Back 909

The correct answer is choice E. The glossopharyngeal nerve is the nerve of the third pharyngeal (branchial) arch. The only muscle derived from the third arch is stylopharyngeus. Choice A is incorrect. The facial nerve is the nerve of the second arch. Choice B is incorrect. The spinal accessory innervates trapezius and sternocleidomastoid, neither of which originates from pharyngeal arches. Choice C is incorrect. CN V3 is the nerve of the first arch. Choice D is incorrect. The hypoglossal nerve is a somatic nerve which innervates muscles of the tongue.

Front 910

Which of the following represents the location of the cell bodies of pain fibers in the glossopharyngeal nerve?A. Otic ganglionB. Nucleus ambiguusC. Trigeminal (semilunar) ganglionD. Spinal nucleus of cranial nerve VE. Superior ganglion of cranial nerve IX

Back 910

The correct answer is choice E. Sensory cell bodies for fibers in CN IX are found in the superior or inferior ganglia of the nerve. Choice A is incorrect. The otic ganglion consists of postsynaptic cell bodies of parasympathetic fibers which supply the parotid gland. Choice B is incorrect. The nucleus ambiguus contains motor neurons for fibers of cranial nerves IX, X and XI. Choice C is incorrect. The trigeminal ganglion contains sensory cell bodies for nerve fibers of each of the divisions of CN V. Choice D is incorrect. The spinal nucleus of V contains secondary cell bodies in the pathway concerned with pain and other general sensation.

Front 911

Which of the following represents the main support of the wall of a bronchus?A. Smooth muscleB. Hyaline cartilageC. Elastic membranesD. Dense irregular connective tissueE. Elastic and collagenous connective tissue

Back 911

The correct answer is choice B. Cartilaginous rings surround the primary bronchi. Choice A is incorrect. Smooth muscle is the major component in the walls of bronchioles. Choice C is incorrect. Elastic fibers are present in all parts of the bronchial tree, but do not represent the major component in any. Choice D is incorrect. Dense, irregular connective tissue is not the major component of the primary bronchus. Choice E is incorrect. Elastic and collagenous connective tissue are present in primary bronchi and their branches, but are not the major components.

Front 912

Which of the following represents the organelle that is typically composed of vesicles and of curved, flattened cisternae that are parallel to one another?1. Centriole2. Mitochondrion3. Golgi complex4. Rough endoplasmic reticulum5. Smooth endoplasmic reticulum

Back 912

The correct answer is choice 3. From the description given, the Golgi complex, choice 3, is the only possible response. The Golgi complex is primarily involved in the packaging of proteins and other secretory products into membrane-bound vesicles for exocytosis. Centrioles, choice 1, are structures involved in formation of the mitotic apparatus along which chromosomes migrate during mitosis. Their shape would resemble cylinders with microtubules inside. Mitochondria, choice 2, are elongated cigar-shaped organelles involved in ATP production. Rough endoplasmic reticulum, choice 4, consists of a network of tubules and flattened cisternae which are studded with ribosomes on the surface. Rough endoplasmic reticulum is mainly responsible for protein synthesis. Smooth endoplasmic reticulum. choice 5, consists of a network of tubules and vesicles. It plays an important role in lipid biosynthesis and it is thought to be part of the inuacellular transport system. So the correct answer to question is choice 3.

Front 913

Which of the following represents the secretory product of the parafollicular cells of the thyroid gland?A. IodineB. ProteaseC. ThyroxineD. CalcitoninE. Thyroglobulin

Back 913

The correct answer is choice D. The thyroid gland produces two types of hormones from two different cell types within the gland. Follicular cells are epithelial cells which produce thyroxin(T4 or tetraiodothyronine) and T3 (triiodothyronine). These hormones control basal metabolic rate. Parafollicular cells secrete calcitonin, the hormone which reduces plasma calcium levels. Choice A is incorrect. Dietary iodine is a mineral required by the follicular cells to produce T3 and T4. Choice B is incorrect. Protease refers to any protein-digesting enzyme. They are used in the thyroid to release T3 and T4 from their storage form. thyroglobulin(choice E). Choice C, thyroxine, as mentioned, is the hormone T4. So the correct answer to question 1 is choice D.

Front 914

Which of the following statements regarding the mechanics of inspiration are incorrect?A. The diaphragm is the primary muscle involved in inspirationB. The ribs are raised superiorlyC. The suprapleural membrane is fixedD. The sternum is fixedE. The tone of the muscles of the anterior abdominal wall is decreased

Back 914

The correct answer is D. Ventilation consists of two phases, inspiration and expiration. These phases occur by the alternate increase and decrease of the capacity of the thoracic cavity, respectively. During inspiration the capacity of the thoracic cavity increases. The process of inspiration is prompted by the diaphragm, which is the primary muscle involved in inspiration (choice A). During this phase the following events occur: The ribs are raised superiorly (choice B), the suprapleural membrane remains fixed (choice C) and the tone of the muscles of the anterior abdominal wall is decreased (choice E). Since the sternum moves anteriorly during inspiration and is not fixed, choice D is the correct answer.

Front 915

Which of the following strata of the epidermis is the LEAST cytodifferentiated?A. BasaleB. CorneumC. SpinosumD. Granulosum

Back 915

he correct answer is choice A. In the stratum basale, undifferentiated epidermal cells specialize and begin their rise to the surface of the skin. This layer of cells is in contact with the dermis. and much mitotic activity is seen here. The cells are cuboidal in shape. As they rise to the next layer, the stratum spinosum(prickly cell layer), they become more flattened. Above that are three to five layers of cells of the stratum granulosum(granular layer). They are flattened and contain keratohyalin granules. Above this is the stratum lucidum (clear layer). These cells have lost their nuclei, and the layer appears clear. The outermost layer is stratum corneum, highly keratinized and composed of dead cells. These dead cells are constantly flaking off (desquamation). The correct answer to question is choice A.

Front 916

Which of the following structural changes is NOT encountered in passing along the respiratory system from the trachea to a respiratory bronchiole?1. Decrease in goblet cells2. Decrease in ciliated cells3. Total loss of cartilage from the wall4. Progressive change from stratified squamous to cuboidal epithelial lining

Back 916

The correct answer is choice 4. As air passes the trachea, it enters the two extrapulmonary bronchi which are outside the lung. Air then passes to the intrapulmonary bronchi, terminal bronchioles, respiratory bronchioles, and finally to alveoli. The terminal bronchioles and respiratory bronchioles lack goblet cells in their epithelium, so choice 1 is true and not the answer. The epithelial lining changes from pseudostratified columnar ciliated to thinner simpler columnar and eventually, in the terminal and respiratory bronchioles, to simple columnar or cuboidal ciliated epithelium without goblet cells. So choice 2 is true and not the answer. Choice 4 is false and is our answer. Choice 3 is also true and not our answer. Cartilage is present in the trachea, extrapulmonary and intrapulmonary bronchi, but absent in the terminal and respiratory bronchioles. So the correct answer to question is choice 4.

Front 917

Which of the following structures contacts posteriorly with the isthmus of the thyroid gland?A. LarynxB. PharynxC. TracheaD. EsophagusE. Carotid Sheath

Back 917

The correct answer is choice C. The isthmus of the thyroid gland rests against the upper tracheal rings. Choice A is incorrect. The larynx is superior to the thyroid gland. Choice B is incorrect. The lower portion of the pharynx (laryngopharynx) lies posterior and lateral to the larynx. Choice D is incorrect. The esophagus runs inferiorly from the larynx. It is located posterior to the trachea. Choice E is incorrect. The carotid sheath, which contains the internal jugular vein, common carotid artery, and vagus nerve, lies lateral to the visceral compartment of the neck, which contains larynx, pharynx, trachea, esophagus and thyroid gland.

Front 918

Which of the following structures contacts the thyroid gland?1. Lingual nerve2. Phrenic nerve3. Thoracic duct4. Thyroarytenoid muscle5. Recurrent laryngeal nerve

Back 918

The correct answer is choice 5. The thyroid gland produces thyroxin and thyrocalcitonin which regulates metabolism and calcium balance, respectively. It consists of two lobes that are bound tightly to the trachea and larynx by the pretracheal layer of the deep cervical fascia. This fascia splits into two layers at the posterior border of each lobe and branches of the inferior thyroid artery and the recurrent laryngeal nerve lie between them. Therefore, branches of the inferior thyroid artery and the recurrent laryngeal nerve contact the thyroid gland directly. So the correct answer to question is choice 5.

Front 919

Which of the following structures is formed from the first branchial (visceral) arch?1. Hyoid bone2. Buccinator muscle3. Stylopharyngeus muscle4. Lateral pterygoid muscle5. Superior parathyroid gland

Back 919

The correct answer is choice 4. The branchial arches form from proliferation of mesoderm in the lateral wall of the pharynx. Each arch gives rise to a cartilaginous bar, a muscle element, an artery and a nerve from the developing brain. Choice 1. the hyoid bone, is derived from the cartilaginous element of the second and third branchial arches. Choice 2, the buccinator, along with all muscles of facial expression, are derived from the second branchial arch. Choice 3, the stylopharyngeus muscle, is derived from the third branchial arch. Choice 4, the lateral pterygoid, and all muscles of mastication, are derived from the first branchial arch and this is, therefore, our correct answer. Choice 5, the superior parathyroid gland, is formed from the fourth pharyngeal pouch. Pharyngeal pouches lie in between the branchial arches. So the correct answer to question is choice 4.

Front 920

Which of the following structures may be found within the posterior mediastinum?1. Heart2. Phrenic nerve3. Thoracic duct4. Arch of the aorta5. Recurrent laryngeal nerve

Back 920

The correct answer is choice 3. The posterior mediastinum refers to the section of the thorax behind the pericardial sac. It is bounded laterally by the mediastinal pleura and by the diaphragm below. Superiorly, it continues into the superior mediastinum. It runs from approximately vertebral level T4 to T12. It contains the descending aorta, the esophagus, the thoracic duct, the sympathetic trunk and the vagus nerve. The superior mediastinum, which is superior to the posterior mediastinum, contains the thymus gland and vascular structures to the heart, including the aortic arch (choice 4) and the brachiocephalic veins and arteries. Choice 1, the heart, is in the middle mediastinum, as is choice 2, the phrenic nerve. Choice 5, the recurrent laryngeal nerve, is considered to be in the superior mediastinum with the thymus gland. So the correct answer to question is choice 3.

Front 921

Which of the following two muscles attach to the pterygomandibular raphe?A. Buccinator and palatopharyngeusB. Medial pterygoid and palatopharyngeusC. levator veli palatini and palatopharyngeusD. Buccinator and superior pharyngeal constrictor

Back 921

The correct answer is choice D. The buccinator arises from the anterior aspect of the pterygomandibular raphe, which extends from the pterygoid hamulus to the posterior end of the mandible. The superior constrictor originates from the posterior aspect of the raphe. Choice A is incorrect. Palatopharyngeus originates from the hard and soft palate and inserts into the thyroid lamina and inferior pharyngeal wall. It forms the muscular core of the palatopharyngeal fold (posterior pillar of the fauces). Choice B is incorrect. The majority of fibers of medial pterygoid arise from the medial surface of the lateral pterygoid plate. Some fibers originate from the pyramidal process of the palatine bone and the tuberosity of the maxilla. It inserts on the medial surface of the ramus of the mandible, inferior to the mandibular foramen. Choice C is incorrect. Levator palati arises from the cartilage of the auditory (Eustachian) tube and inserts into the palatal aponeurosis.

Front 922

Which of the following types of epithelium is well adapted for secretory or absorptive functions?A. Simple columnarB. Simple squamousC. Stratified cuboidalD. Stratified squamousE. Psuedostratified columnar

Back 922

The correct answer is choice A. Simple columnar epithelial cells are tall and single layered, and are found lining the digestive system from the stomach through the anus. Therefore, they are involved in both absorption and secretion, as the digestive lining both secretes enzymes and absorbs digested food and water. Simple squamous epithelial cells are single layered and flattened (thin). They are found in areas where a narrow distance between two areas is desirable, such as the lining of areas of the Bowman's capsule, and the endothelium of blood vessels. Simple cuboidal epithelium is cubelike and single layered, and is often found lining the ducts of glands. Stratified cuboidal is not generally found. Stratified squamous epithelium is multi-layered flat cells, and lines the oral cavity and esophagus. These two areas are not major absorptive or secretory sections. Pseudostratified columnar epithelium appears to be multilayered, but is not. Non-ciliated versions are found in parotid ducts and other glands, while ciliated types line the bronchi and bronchioles. So the correct answer to question is choice A.

Front 923

Which of the following types of tissues can be demonstrated on the posterior slope of the articular eminence?A. Hyaline cartilageB. FibrocartilageC. Fibrous connective tissueD. Articular cartilageE. Elastic cartilage

Back 923

The correct answer is choice C. Although the temperomandibular joint shares many characteristics with other joints, it also is distinct in many ways. While most articular surfaces in joints are covered by hyaline cartilage, the surfaces in the TMJ are covered by fibrous connective tissue. In addition, the condyle and bone of the articular eminence do not make direct contact, but rather, are separated by the fibrous disc of the TMJ. In older people, the fibrous connective tissue may develop small areas containg cartilage, and therefore become more like fibrocartilage. Note that elastic cartilage is found in areas such as the outer ear and epiglottis, where flexibility is needed. The correct answer to question is choice C.

Front 924

Which of the lymphoid tissues in the body are considered subepithelial and nonencapsulated?1. Thymus gland and lymph nodes2. Lymph nodes and aggregated nodules3. Pharyngeal tonsils and thymus gland4. Peyel's patches and pharyngeal tonsils

Back 924

The correct answer is choice 4. Peyer's patches are clusters of aggregated lymph follicles located within the mucosa of the small intestine. The pharyngeal tonsils are located on the posterior wall of the nasopharynx. Both the Peyer's patches and pharyngeal tonsils are not enclosed in a capsule and are subepithelial. Choice 1 is incorrect. The thymus gland is encapsulated by a dense fibrous capsule and contains an epithelial framework inside the gland. Lymph nodes are also encapsulated, so choice 2 is also incorrect. Aggregated lymph nodules are another name for Peyer's patches. Choice 3 is incorrect because, as noted, the thymus gland is encapsulated. It should be noted that Peyer's patches are believed to be involved in producing precursors of intestinal plasma cells which produce IgA. So the correct answer to question is choice 4.

Front 925

Which region of dentin is the most highly mineralized?1. The peritubular2. The intertubular3. The interglobular

Back 925

The correct answer is choice 1. Dentin forms the bulk of the tooth. It is permeated by tubules which run from thc pulpal surface toward the amelodentinal and cementodentinal junctions. Between the tubules lie the bulk of the dentin known as intertubular dentin. Peritubular dentin, choice 1, is more highly mineralized than intertubular dentin, choice 2. The interglobular dentin, choice 3, refers to unmineralized or hypomineralized regions that remain between the mineralized dentin. These are chiefly found in the crown near the dentinoenamel junction. So the correct answer to question is choice 1.

Front 926

White matter of the spinal cord consists chiefly of which of the following? A. Perineurium B. Myelinated axons C. Unmyelinated axons D. Nerve cell bodies E. Loose connective tissue

Back 926

The correct answer is choice B. Myelinated nerve fibers appear white in unfixed, fresh tissue as well as in standard fixed and stained preparations. Choice A is incorrect. The perineurium refers to the thin layer of connective tissue that invests nerve fibers; it is not grossly visible. Choice C is incorrect. Unmyelinated axons do not have the shiny, white appearance caused by the presence of the lipid-rich myelin. Choice D is incorrect. Nerve cell bodies comprise most of what is visible as grey matter in unstained sections of spinal cord and brain. Choice E is incorrect. Loose connective tissue is not present in abundance in the central nervous system.