Histo Exam 3

Front 1

oral mucosa

Back 1

composed of a wet stratified squamous epithelium (nonkeratinized, parakeratinized or orthokeratinized) and an underlying dense irregular collagenous connective tissue, may be divided into three classifications, lining mucosa, masticatory mucosa and specialized mucosa, lines the oral cavity

Front 2

masticatory mucosa

Back 2

cover regions of the oral cavity that are exposed to considerable frictional and shearing forces (gingival, dorsal surface of the tongue and hard palate), composed of parakeratinized to completely keratinized stratified squamous epithelium with an underlying dense irregular collagenous connective tissue

Front 3

lining mucosa

Back 3

covers the remainder of the oral cavity, composed of a nonkeratinized stratified squamous epithelium overlying a looser type of dense irregular collagenous connective tissue

Front 4

specialized mucosa

Back 4

cover aspects of the oral mucosa that contain taste buds (dorsal surface of the tongue and patches of the soft palate and pharynx), specialized to perceive taste

Front 5

salivary amylase

Back 5

secreted by the three pairs of major salivary glands (parotid, submandibular and sublingual), break down carbohydrates, salivary glands also secrete lactoferrin and lysozymes, antibacterial agents, and secretory immunoglobulin

Front 6

boundaries of the oral cavity

Back 6

anterior boundary formed by the lips while the palatoglossal folds form the posterior boundary

Front 7

lips

Back 7

composed of three regions, the skin aspect, the vermilion zone and the mucous (internal, wet) aspect, core of the lip is composed of skeletal muscle fibers, is parakeratinized

Front 8

skin aspect of lip

Back 8

covered with thin skin and is associated with sweat glands, hair follicles and sebaceous glands, continuous with the vermilion zone

Front 9

vermilion zone of the lip

Back 9

pink region of the lip, also covered by thin skin, devoid of sweat glands and hair follicles, although occasional, nonfunctional sebaceous glands are present, called vermilion zone because of its color (red)

Front 10

rete apparatus

Back 10

portion of the lip, the interdigitation between the epithelial and connective tissue components, capillary loops of the dermal papillae are close to the surface of the skin imparting the pink color to the vermilion

Front 11

mucous (internal) aspect

Back 11

always wet and is lined by stratified squamous nonkeratinized epithelium, the subepithelial connective tissue is of the dense, irregular collagenous type and houses numerous mostly mucous, minor salivary glands

Front 12

teeth

Back 12

there are 20 deciduous (milk) and 32 permanent (adult) teeth (20 succedaneous teeth and 12 molars)

Front 13

alveolus of the tooth

Back 13

bony socket that holds the tooth (at the root), bony continuation of the mandible and maxilla, separated from adjacent alveolus by interalveolar septum

Front 14

regions of the alveolus

Back 14

1. cortical plates-disposed lingually and labially, form a firm supporting ledge of compact bone
2. spongiosa-cancellous bone that lines the cortical plates, have nutrient arteries that supply the alveolus
3. alveolar bone proper-surrounded by the spongiosa as well, thin layer of compact bone

Front 15

periodontal ligament (PDL)

Back 15

dense, irregular collagenous connective tissue that holds the tooth in the alveolus, composed of type I collagen, located between the cementum of the root and the bony alveolus, ends are embedded in the alveolus and cementum as Sharpey’s fibers which permit the PDL to suspend the tooth in its socket

Front 16

fibroblasts and the PDL

Back 16

most abundant cells of the PDL, manufacture the collagen and help resorb collagen fibers thus being responsible for the high turnover of collagen in the PDL, mast cells, macrophages, plasma cells and leukocytes are also present in the PDL

Front 17

nerves of the PDL

Back 17

1. autonomic fibers-regulate the luminal diameter of the arteriorles
2. pain fibers-mediate pain sensation
3. proprioceptive fibers-responsible for the perception of spatial orientation

Front 18

jaw-jerk reflex

Back 18

proprioceptive fibers in the PDL are responsible for this, involuntary opening of the jaw when one unexpectedly bites down on something hard, causes relaxation of the muscles of mastication and contraction of muscles responsible for opening of the jaw, protect teeth from fracture

Front 19

gingival

Back 19

supports the tooth as well and its epithelium seals the oral cavity from the subepithelial connective tissue

Front 20

clinical crown

Back 20

portion of the tooth that is visible in the oral cavity

Front 21

tooth root

Back 21

region housed within the alveolus

Front 22

tooth cervix

Back 22

portion between the root and crown, where the enamel and cementum mineralized portions meet

Front 23

pulp

Back 23

soft, gelatinous connective tissue found on the inside of the tooth, subdivided into the pulp chamber and the root canal (which communicates with the periodontal ligament via the apical foramen where blood vessels and nerves enter), a richly vascularized and innervated loose connective tissue, surrounded by dentin, has lymph components

Front 24

enamel

Back 24

overlies dentin of the crown, composed of 96% calcium hydroxyapatite and 4% organic material and water, is the hardest substance of the body, cannot be repaired since the ameloblasts die before the tooth erupts into the cavity

Front 25

ameloblasts

Back 25

give rise to enamel, elaborate enamel daily in 4-8 micrometer segments called rod segments, successive rod segments adhere to one another forming enamel rods which extend over the complete width of the enamel from the dentinoenamel junction to the enamel surface

Front 26

preameloblasts

Back 26

precursor to ameloblasts, derive from stratum intermedium inducing the simple squamous cells of the inner enamel epithelium to differentiate into pre-ameloblasts

Front 27

striae of Retzius

Back 27

analogous to growth rings in a tree trunk, alternating sequences of hypocalcified and calcified enamel formation

Front 28

dentin

Back 28

forms the bulk of the tooth, composed of 70% calcium hydroxyapatitie and is the second hardest substance of the body, has high elasticity and protects the overlying brittle enamel

Front 29

type I collagen of the tooth

Back 29

composes most of the organic substance, associated with proteoglycans and glycoproteins

Front 30

odontoblasts

Back 30

cells that produce dentin, they maintain their association with dentin for the life of the tooth, located at the periphery of the pulp, have cytoplasmic extensions (odontoblastic processes) that occupy dentinal tubules that extend from the pulp to the dentinoenamel and the dentinocemental junctions

Front 31

pre-odontoblasts

Back 31

precursors to odontoblasts, the most peripheral cells of the dental papilla (those in contact with the basal lamina) differentiate into pre-odontoblasts

Front 32

lines of Owen

Back 32

analogous to striae of Retzius, but found in the dentin

Front 33

gingival sulcus

Back 33

space between crown of tooth and gingival (gum)

Front 34

cementum

Back 34

overlies dentin of the roots, composed of about 50% calcium hydroxyapatite and 50% organic matrix and bound water, as hard as bone, also similar to bone because it houses cementocytes within lenticular spaces (known as lacunae)

Front 35

cementoblasts

Back 35

responsible for the formation of cementum, cover cementum at its interface with the periodontal ligament and continue to elaborate cementum for the life of the tooth

Front 36

odontoclasts

Back 36

responsible for resorbtion of cementum, resorb cementum of the root during replavement of deciduous teeth by their succedaneous counterparts

Front 37

concentric zones of the pulp

Back 37

surround a central core
1. the outermost odontoblastic zone-composed of a single layer of odontoblasts
2. cell free zone-forms the layer deep to the odontoblastic zone, devoid of cells
3. cell-rich zone-consists of fibroblasts and mesenchymal cells, deepest zone

Front 38

core of the pulp

Back 38

resembles most other loose connective tissues but lack adipose cells

Front 39

nerve fibers of the pulp

Back 39

1. sympathetic (vasomotor)-control the luminal diameters of blood vessels
2. sensory-responsible for the transmission of pain sensations, forms Raschokow plexus deep to the cell-rich zone and enter the dentinal tubule

Front 40

odontogenesis

Back 40

begins at the 6th to 7th week of gestation when the ectodermally derived oral epithelium proliferates forming dental lamina surrounded by neural crest-derived ectomesenchyme

Front 41

gingival (gums)

Back 41

attached to the enamel surface by a thin, wedge-shaped, stratified squamous nonkeratinzed epithelium, known as the junctional epithelium, itself is composed of stratified squamous epithelium that is either orthokeratinized or parakeratinized, deep to the ephithelium is a dense, irregular collagneous connective tissue of type I collagen, attaches to the enamel surface by the formation of hemidesmosomes

Front 42

junctional epithelium

Back 42

region of the gingival epithelium that attaches to the enamel surface, forms a collar around the neck of the tooth, barrier between the oral cavity and the sterile gingival connective tissue

Front 43

palate

Back 43

comprised of the hard and soft palate and the uvula, separates the oral cavity from the nasal cavity

Front 44

hard palate

Back 44

positioned anteriorly, immovable and receives its name from the bony shelf contained within it, masticatory mucosa covers the oral aspect, anterior lateral region has lots of adipose tissue while the posterior lateral region exhibits acini of mucous minor salivary glands, nasal aspect has respiratory epithelium

Front 45

soft palate

Back 45

movable and its core is occupied by skeletal muscle responsible for its movements, lining mucosa covers its oral surface, nasal aspect has respiratory epithelium

Front 46

uvula

Back 46

most posterior aspect of the soft palate, similar histologically to the soft palate, epithelium is composed solely of stratified squamous nonkeratinized epithelium, connective tissue is also a dense irregular collagenous type and possesses mucous minor salivary glands, core is composed of skeletal muscle that is responsible for its movement

Front 47

tongue

Back 47

largest structure in the oral cavity, extremely mobile

Front 48

muscle fibers of the tongue

Back 48

1. extrinsic muscles-those that originate outside the tongue, responsible for moving the tongue in and out of the mouth as well as from side to side
2. intrinsic muscles-those that originate within and insert into the tongue, alter the shape of the tongue, arranged in four groups, superior and inferior longitudinal, vertical and transverse

Front 49

dorsal surface of the tongue

Back 49

has two unequal regions the larger anterior 2/3 and the smaller posterior 1/3, separated from one another by sulcus terminalis whose posterior part is the foramen cecum, anterior 2/3 is covered by lingual papillae (4 types), posterior third is uneven because of the presence of the lingual tonsil, most posterior portion of the tongue is the root of the tongue

Front 50

types of lingual papillae

Back 50

filiform, fungiform, foliate and circumvallate, found on the dorsal and lateral aspect of the tongue anterior to the sulcus terminalis

Front 51

filiform papillae

Back 51

numberous, lack taste buds, their role is to INC friction between the tongue and food, give velvety appearance to the tongue, covered by stratified squamous keratinized epithelium and help to scrape food off the surface

Front 52

fungiform papilla

Back 52

resembles a mushroom, occur on the margin of the tongue, has stratified squamous nonkeratinized epithelium, evident as red dots distributed randomly, have taste buds on the dorsal aspect of their cap

Front 53

foliate papillae

Back 53

located along the posterolateral aspect of the tongue, appear as vertical furrows, have functional taste buds in the neonate but degenerate by the 2nd-3rd year of life, glands of von Ebner empty into the base of the furrows

Front 54

circumvallate papillae

Back 54

located in front of the sulcus terminalis, associated with Ebner’s glands, 8 to 12, large, submerged into the surface of the tongue, surrounded by an epithelially lined groove whose base is peireced by the ducts of the Ebner’s glands, the epithelial lining of the groove and the side have taste buds

Front 55

ventral surface of the tongue

Back 55

associated with lingual frenulum, on either side of the frenulum are deep lingual veins, why nitroglycerin is administered sublingual, blood vessels are on the bottom side of the tongue

Front 56

taste buds

Back 56

intraepithelial sensory organs that function in the perception of taste, approx. 3000 taste buds, composed of 60 to 80 spindle shaped cells that is paler than the surrounding epithelium

Front 57

taste pore

Back 57

opening formed by the squamous epithelial cells that overlie the taste bud, found at the narrow end of the taste bud

Front 58

cell types of the taste bud

Back 58

1. basal cells (type IV cells)-function as reserve cells and regenerate the cells of the taste buds which have an average lifespan of 10 days
2. dark cells (type I cells)-come from basal cells
3. light cells (type II cells)-come from mature dark cells
4. intermediate cells (type III cells)-come from light cells, then die

Front 59

nerve fibers of taste buds

Back 59

enter cell types I, II and III, each of these cell types have long microvilli (taste hairs) that protrude from the taste pore

Front 60

tastants

Back 60

interact wither with ion channels or with receptors located on the microvilli of the taste cells, effecting electrical alterations in the resting potentials of these cells initiating an action potential

Front 61

taste sensations

Back 61

5 of them, salty, sweet, sour, bitter, and umami (savory taste via glutamate receptors), every taste bud can discern each of the five, but specialize in two of the 5, reaction is due to presence of specific ion channels (salty and sour) and G protein-coupled membrane receptors (bitter, sweet and umami), taste sensation more due to olfaction than tast buds

Front 62

general plan of the alimentary canal

Back 62

comprises of four concentric layers, the mucosa, submucosa, muscularis externa and serosa (adventitia), innervated by the enteric (intrinsic) and parasympathetic and sympathetic (extrinsic) nerves

Front 63

enteric (intrinsic) innervation

Back 63

myenteric (Auerbach) and submucosal (Meissner’s) plexuses, sensory from epithelium and motor to smooth muscle, contractions occur in the total absence of extrinsic innervation, self-contained, comprised of numerous repeating ganglia, extends from esophagus to anus, responsible for controlling the secretory and motile function sof the alimentary canal, has just as many nerve fibers as the spinal cord

Front 64

parasympathetic and sympathetic (extrinsic) innervation

Back 64

parasympathetic (cholinergic) stimulates peristalsis, inhibits sphincter muscles, trigger secretory activity, sympathetic (adrenergic) inhibits peristalsis, activates sphincter activity, plays a role in modifying the enteric system, if remove the para. and sym. the alimentary canal can perform all of its functions without any major problems

Front 65

vagus nerve

Back 65

gives the parasympathetic nerve supply to the gut, except for the descending colon and rectum which come from the sacral outflow

Front 66

vagovasal reflex

Back 66

sensory from the vagus nerve and responses to the information are then conveyed by the vagal fibers to the alimentary canal

Front 67

splanchnic nerves

Back 67

give sympathetic innervation to the alimentary canal, vasomotor, controlling the blood flow to the alimentary canal

Front 68

mucosa

Back 68

lines the lumen of the alimentary canal, composed of epithelium and lamin propria (contains glands, lymph vessels and lymphoid nodules (MALT)) deep to it, surrounding this is the muscularis mucosae (composed of an inner circular layer and outer longitudinal layer of smooth muscle)

Front 69

submucosa

Back 69

surround the mucosa with a dense, irregular fibroelastic connective tissue layer, houses no glands except in the esophagus and duodenum, contains blood and lymph vessels as wellas a component of the enteric nervous system (Meissner’s submucosal plexus)

Front 70

Meissner’s submucosal plexus

Back 70

also houses postganglionic parasympathetic nerve cell bodies, controls the motility of the mucosa (and submucosa a bit) and the secretory activities of its glands, concerned with local conditions mostly

Front 71

muscularis externis

Back 71

usually composed of inner circular and outer longitudinal smooth muscle layers, invests the submucosa, responsible for peristaltic activity, houses Auerbach’s myenteric plexus

Front 72

interstitial cells of Cajal

Back 72

undergo rhythmic contractions and are considered to be the pacemakers for th contraction of the muscularis externa

Front 73

Auerbach’s myenteric plexus

Back 73

sandwiched between the two muscle layers and regulates the activity of the muscularis externa, houses postganglionic parasympathetic nerve cell bodies, responsible for peristaltic motility, concerned with local conditions as well as along the entire digestive tract

Front 74

serosa (adventitia)

Back 74

thin connective tissue layer that envelopes the muscularis externa, may or may not be surrounded by the simple squamous epithelium of the visceral peritoneum, serosa if intraperitoneal, adventitia if retroperitoneal

Front 75

sensory components of the alimentary canal

Back 75

convey information concerning the luminal contents, muscular status and secretory status of the gut to the plexuses

Front 76

esophageal mucosa

Back 76

lined with stratified squamous nonkeratinized epithelium, regenerated much slower than the rest of the GI tract, has a unique muscularis mucosa that is a single longitudinal layer of smooth muscle which become thicker at the stomach

Front 77

Langerhans cells

Back 77

interspersed within the keratinocytes of the epithelium, are antigen-presenting cells, phagocytose and degrade antigens into small polypeptides known as epitopes, also synthesize MHC II molecules and attach the epitopes on here and bring them to lymph nodes where lymphocytes break them down

Front 78

esophageal cardiac glands

Back 78

produce mucus that coats the lining of the esophagus, lubricating it to protect the epithelium as the bolus is passed to the stomach

Front 79

esophageal submucosa

Back 79

houses esophageal glands proper, the esophagus and the duodenum are the only two regions to have glands in the submucosa

Front 80

esophageal glands proper

Back 80

composed of serous and mucous cells, mucous cells have basally located, flattened nuclis while serous cells have round, centrally placed nuclei, contain pepsinogen and lysozyme, are tubuloacinar arranged in small lobules drained by a single duct

Front 81

esophageal muscularis externa

Back 81

composed of both skeletal (dominant in upper 1/3) and smooth muscle cells (dominant in the lower 1/3)

Front 82

esophageal adventitia/serosa

Back 82

adventitia above the diaphragm, serosa below the diaphragm

Front 83

esophageal sphincters

Back 83

no anatomical sphincter but two physiological sphincters, the pharyngoesohpageal sphincter and the internal and external gastroesophageal sphincters, prevent reflux into the pharynx from the esophagus and into the esophagus from the stomach

Front 84

hiatal hernia

Back 84

caused by abnormal development of the esophagus passing the diaphragm, causes a gap in the daphramg around the wall of the esophagus that permits herniation of the stomach into the thoracic cage, weakens the gastroesophageal sphincter allowing reflux of the stomach contents into the esophagus (GERD)

Front 85

Barrett’s syndrome

Back 85

a premalignant condition due to GERD, when normal stratified squamous epithelium is replaced by simple columnar in the lowest region of the esophagus, characterized by a reddish color on the metaplastic area

Front 86

stomach

Back 86

acidifies and converts bolus into chyme, produces digestive enzymes pepsin, rennin, and gastric lipases and paracrine hormones, mucosa and submucosa thrown into rugae (longitudinal folds), surface covered by gastric pits, has 4 parts (cardia, fundus (freq. filled with gas), body (formation of chyme), pylorus (release of chyme into duodenum))

Front 87

ghrelin

Back 87

maintains intraluminal pressure of the stomach, induces the sensation of hunger but also modulates receptive relaxation of the smooth muscle fibers of the muscularis externa

Front 88

rugae

Back 88

found in all the gastric regions, longitudinal folds of the mucosa and submucosa (transverse in the pyloric antrum), permit expansion of the stomach as it fills

Front 89

gastric pits (foveolae)

Back 89

epithelial lining that invaginates into the mucosa, shallowest in the cardiac region and deepest in the pyloric region, INC SA of the gastric lining, have 5-7 gastric glands of the lamina propria that empty into the bottom of each gastric pit

Front 90

stomach mucosa

Back 90

epithelium has surface mucous lining cells that secrete mucous to protect the stomach from autodigestion, is simple columnar, short microvilli on the surface, lamina propria has smooth muscle, connective tissue, gastric glands (lots here, called fundic (oxyntic) glands), plasma cells, lymphocytes, fibroblasts

Front 91

gastic glands

Back 91

simple branched tubular glands found in the lamina propria of the cardia, fundus and pylorus, possess an isthmus, neck and base, glands have different lengths in different regions of the stomach

Front 92

types of gastric glands in the fundic gland

Back 92

from superficial to deep: surface lining cell, regenerative cells, mucous neck cells and oxyntic parietal cells (both in the isthmus and neck), and zymogenic (chief) cells and enteroendocrin cells (DNES cell, APUD cell) (both in the base)

Front 93

mucus neck cells

Back 93

produce soluble mucus that is mixed with and lubricates the chyme, reducing friction as it moves along the digestive tract, short microvilli, basally located nuclei, and a well-developed golgi apparaturs and RER, mito located mainly in the basal region of the cell

Front 94

regenerative (stem) cells

Back 94

located in the neck and isthmus, few and thin, rich supply of ribosomes, basal nuclei, form zonulae occludentes and adherenets with neighbors, proliferate to replace all of the specialized cells lining the fundic glands, gastric pits and luminal surface

Front 95

parietal oxyntic cells

Back 95

found in upper half of gastric gland, secrete HCl and gastric intrinsic factor (important for absorption of Vita B12 in the ileum), intracellular canaliculi lined by microvilli, gastric juices (low pH=2.0), pepsinogen to pepsin, rich in mito, with HCl production microvilli INC and tubulovesicular system DEC

Front 96

lack of gastric intrinsic factors

Back 96

results in pernicious anemia (PA), DEC in vita B12, associated with atrophic gastritis (DEC in parietal and chief cells, with little or no pepsin/HCl activity), loss of ability to produce GIF with aging

Front 97

chief (zymogenic) cells

Back 97

found in the lower half of the gland, secrete pepsinogen and presursors to rennin and lipase, release them into the lumen, rich supply of RER, extensive Golgi, neural stimulation by the vagus is the main contributor to pepsinogen release, binding of secretin to receptors in the basal plasma membrane of chief cells triggers a second messenger system that also leads to exocytosis of pepsinogen

Front 98

DNES cells (APUD or eneteroendocrine cells)

Back 98

located mainly in the lower half, must have a special stain to see them, produce endocrine, paracrine and neurocrine secretions, sit on the basal lamina, stain with silver, found in the respiratory, pancreas and CNS

Front 99

types of DNES cells

Back 99

1. open type-those that reach the lumen of the gut via long apical processes with microvilli
2. closed type-those that do not reach the lumen of the gut

Front 100

stomach muscularis mucosae

Back 100

arranged in three layers, inner circular and outer longitudinal are well defined, there is an occasional third layer whose fibers are disposed circularly (outmost circular), not always evident

Front 101

mucosa of cardiac vs. pyloric regions

Back 101

cardiac region gastric pits are shallower and the base of its glands is highly coiled, main cell type of cardiac region is the surface-lining cells, main cell type in the pyloric region is the mucous neck cell

Front 102

submucosa of the stomach

Back 102

dense irregular CT, rich vascular and lymphatic network, no main differences from the typical submucosa

Front 103

muscularis externa of the stomach

Back 103

composed of three layers (an innermost oblique, middle circular and outer longitudinal, incomplete inner oblique, thick middle circular forms pyloric sphincter, outer longitudinal most evident in the cardiac region but poorly developed in the pylorus

Front 104

serosa of the stomach

Back 104

the entire stomach is invested by serosa, composed of a thin, loose, subserous CT covered by a smooth, wet, simple squamous epithelium

Front 105

replacement of surface mucous and mucous neck cells

Back 105

replaced every 3-5 days, gastric glands replaced at relatively slower rate, up to once a year

Front 106

gastrin

Back 106

hormone that stimulates contraction of the muscularis externa of the pyloric region and relaxation of the pyloric sphincter, facilitates emptying of the stomach and the degree of its distention

Front 107

phases of HCl production

Back 107

cephalic (thought of food), gastic (food in stomach), and intestinal (food in small intestine)

Front 108

ulcers

Back 108

most common cause of ulcers is the use of NSAIDs ibuprofen and aspirin, inhibit the manufacture of prostaglandins thus precluding their protective effects on the stomach lining, heliobacter pylori may also cause ulcers

Front 109

gastric carcinomas

Back 109

one of the most common gastrointestinal malignancies, may be localized to any region of the stomach but most found in the lesser curvature and the pyloric antrum

Front 110

small intestine

Back 110

21-25 feet long, has three regions (duodenum, jejunum, ileum), surface modifications for INC SA by 400-600X

Front 111

modifications of the small intestine

Back 111

1. plicae circulares (valves of Kerckring)-INC SA by 2-3X and DEC velocity of the movement of chyme along the alimentary tract, transverse folds of the submucosa and mucosa that form semicircular to helical elevations, permanent fixtures found all the way to the proximal half of the ileum
2. intestinal villi-INC SA by 10X, epithelially covered protrusions of the lamina propria, core of each villus contains capillary loops, a lacteal (lympathic channel) and a few smooth muscle fibers, permanent structures, found more so in the duodenum
3. microvilli-INC SA by 20X

Front 112

crypts of Lieberkuhn

Back 112

invaginations of the epithelium into the lamina propria between the villi form these intestinal glands, also augment the surface area of the small intestine, composed of surface absorptive cells, enteroendocrine cells, regenerative cells, goblet cells and paneth cells

Front 113

intestinal mucosal epithelium

Back 113

contain villi, composed of surface absorptive cells, goblet cells and DNES cells, lamina propria characterized by crypts of Lieberkuhn

Front 114

surface absorptive cells

Back 114

most numerous cells of the epithelium, tall columnar cells that function in terminal digestion and absorption of water and nutrients, form chylomicrons, have microvilli (brush border) and intercellular junctions (terminal bars, zonulae occludentes and adherents, gap junctions, and desmosomes)

Front 115

goblet cells

Back 115

secretes mucinogen that is converted to mucous for protection, unicellular glands, number INC toward the ileum with the duodenum having the fewest of these

Front 116

DNES cells

Back 116

produce paracrine and endocrine hormones, several types that secrete gastrin, CCK and gastric inhibitory peptide, compose about 1% of the small intestine cells

Front 117

M cells (microfold cells)

Back 117

antigen presenting cell, phagocytose and transport antigens from the lumen to the lamina propria, squamous like cells in regions where lymphoid nodules abut the epithelium, belong to the mononuclear phagocyte system of cells

Front 118

intestinal lamina propria

Back 118

occupies the villi and in between intestinal glands -> Crypts of Lieberkuhn, contains CT, lymphoid tissue, villus lacteals, and have paneth cells and regenerative cells

Front 119

Crypts of Lieberkuhn

Back 119

INC SA of the intestinal lining, simple (or branched) tubular glands, open into the intercillar spaces as perforations of the epithelial lining, upper half is surface absorptive and goblet cells, lower half is regenerative cells, DNES cells and Paneth cells

Front 120

lacteals

Back 120

blindly ending lymph capillaries, located in the cores of villi, deliver their contents into the submucosal lymphatic plexus, then delivered to thoracic duct

Front 121

regenerative cells of the small intestine

Back 121

restore epithelial cells every 5-6 days, paneth cells every 4 weeks, stem cells that undergo extensive proliferation to repopulate the epithelium of the crypts, mucosal surface and villi

Front 122

paneth cells

Back 122

secrete lysozyme (antibacterial), defensin and TNF-alpha, regulation of intestinal flora, occupy the bottom of the crypts of Lieberkuhn

Front 123

muscularis mucosae of the small intestine

Back 123

two layers, an inner circular layer and an outer longitudinal layer of smooth muscle cells

Front 124

antimitotic drugs

Back 124

used because of the epitheliums higher rate of cell renewal

Front 125

Peyter’s patches of the ileum

Back 125

are lymphoid nodules in the ileum, housed in the lamina propria, located in the wall of the ileum that is opposite the attachment of the mesentery

Front 126

submucosa of the small intestine

Back 126

composed of dense, irregular fibroelastic CT with a rich lymphatic and vascular supply, contain Brunner’s Glands, innervation from the submucosal Meissner’s plexus

Front 127

Brunner’s glands

Back 127

unique to the duodenum, produces alkaline mucin to neutralize HCl in response to parasympathetic stimulation, bicarbonate rich, produces urogastrone (human epidermal growth factor) that inhibits gastric HCl production and amplifies the rate of mitotic activity in epithelial cells, ducts penetrate the muscularis mucosae and pierce the base of the crypts of Lieberkuhn to deliver their secretory product into the lumen of the duodenum

Front 128

muscularis externa of small intestine

Back 128

composed of an inner circular layer and an outer longitudinal smooth muscle layer, has Auerbach’s myenteric plexus located between the two muscle layers, is the intrinsic neural supply of the external muscle coat, responsible for the peristaltic activity of the small intestine

Front 129

serosa and adventitia of small intestine

Back 129

jejunum, ileum and proximal and distal duodenum are covered by serosa, 2nd, 3rd, and part of 4th part of duodenum are covered by adventitia

Front 130

Meckel’s diverticulum

Back 130

2% of Caucasian population, congenital anomaly, a remnant of the vitelline duc, most are asymptomatic, but some can cause bleeding and intestinal obstruction, mostly due to prolapse of the ileum into the diverticulum

Front 131

Immunoglobulin A

Back 131

produced by plasma cells in the lamina propria and is recirculated through the liver and gallbladder, bound to the glycocalyx to defend the body against antigenic onslaught

Front 132

cholear toxin

Back 132

causes diarrhea, fluid loss may amount to as much as 10 L/day, may lead to circulatory shock and death, within a few hours, accompanied by electrolyte imbalance, a contributory factor in the lethal effect of cholera

Front 133

peristaltic rush

Back 133

if the intestinal mucosa is exposed to toxic substances, the muscularis externa can undergo intense, swift contractions of long duration known as peristaltic rush, propel the chyme into the colon within minutes for elimination as diarrhea

Front 134

malabsorption

Back 134

may occur even though the pancreas delivers its normal complement of enzymes, sprue are disease that lead to malabsorption

Front 135

gluten enteropathy

Back 135

a type of sprue caused by gluten, destroys the microvilli and even the villi of susceptible persons

Front 136

large intestine

Back 136

includes cecum with appendix, colon, rectum, anal canal, possesses no special mucosal folds and lack villi, absorption of electrolytes and fluids, houses bacteria that produce vita B12 (hematopoiesis) and vita K (coagulation) and contribute to feces, produces copious amounts of mucus, ~1.5 m long

Front 137

colon mucosa

Back 137

simple columnar epithelium, numerous goblet cells, surface absorptive cells most numerous, occasional enteroendocrine cells, lacks folds or villi

Front 138

colon lamina propria

Back 138

has crypts of Lieberkuhn, but no Paneth cells, resembles small intestine

Front 139

colon muscularis mucosae

Back 139

inner circular and outer longitudinal layer, resembles small intestine

Front 140

colon muscularis externa

Back 140

inner circular and outer longitudinal layer, inner circular layer is thin, fascicles of the outer longitudinal layer aggregate into three spaced bands called taeniae coli

Front 141

colon serosa and adventitia

Back 141

numerous fat filled pouches called appendices epiploicae surrounded by the serosa

Front 142

enteritis

Back 142

intense irritation of the colonic mucosa, results in the secretion of large quantities of mucus, water and electrolytes

Front 143

diarrhea

Back 143

voiding of copious quantities of liquid stool protects the body by diluting and eliminating the irritant

Front 144

pseudomembranous colitis

Back 144

an inflammatory disease of the bowel, may result from mercury poisoning, intestinal ischemia, and bronchopneumonia, but most freq. due to prolonged antibiotic therapy, symptoms include fluid accumulation in the small intestine, low grade fever, copious watery diarrhea, severe abdominal pain

Front 145

rectum

Back 145

similar to colon but crypts are fewer and deeper, transverse rectal folds

Front 146

anal canal

Back 146

the constricted continuation of the rectum, mucosa has longitudinal folds (anal columns), anal columns overlie rich rectal venous plexus in submucosa, crypts are short and few, absent in the distal half of the canal

Front 147

anal canal epithelium

Back 147

simple cuboidal to anal valves (pectinate line), becomes stratified squamous non-keratinized distal to anal valves, changes to stratified squamous keratinized at anus

Front 148

pectinate line

Back 148

division of the anal canal, different blood supply (inferior mesenteric vs. internal iliac), venous drainage (portal vs. IVC), nerve supply (autonomic vs. somatic), lymphatic drainage (internal iliac vs. inguinal)

Front 149

internal hemorrhoids

Back 149

lie superior to the pectinate line, involve superior rectal vein

Front 150

external hemorrhoids

Back 150

lie inferior to the pectinate line, involve middle (internal iliac) and inferior rectal (internal pudendal) veins

Front 151

lamina propria of anal canal

Back 151

has sebaceous glands, large apocrine glands, hair follicles and large veins, fibroelastic connective tissue, houses anal glands at the rectoanal junction and circumanal glands at the distal end of the anal canal

Front 152

muscularis mucsoa of the anal canal

Back 152

has inner circular and outer longitudinal layers, terminate at the anal valves

Front 153

anal submucosa

Back 153

consists of fibroelastic tissue, houses two venous plexuses, the internal hemorrhoidal plexus and the external hemorrhoidal plexus

Front 154

anal muscularis externa

Back 154

has inner circular and outer longitudinal layers, inner circular forms the internal anal sphincter (smooth muscle)

Front 155

external anal sphincter

Back 155

skeletal muscle of the perineum, surrounds the internal anal sphincter

Front 156

hemorrhoids

Back 156

INC in the size of the vessels of the submucosal venous plexuses, associated with painful defecation, appearance of fresh blood with defecation and anal itching

Front 157

appendix

Back 157

histological appearance of the appendix resembles that of the colon, except that it is much smaller in diameter, has a richer supply of lymphoid elements and contains many more DNES cells in its crypts, simple columnar

Front 158

appendicitis

Back 158

inflammation of the appendix, greater in teens, usually caused by obstruction of the lumen which results in inflammation accompanied by swelling and unremitting severe pain the RLQ

Front 159

extramural glands of the digestive system

Back 159

include the salivary glands, pancreas and liver, the secretory products of these glands assist in the digestive process and are delivered to the lumen of the alimentary tract by a system of ducts

Front 160

salivary glands

Back 160

produce saliva, facilitate the process of tasting food, initiate its digestion and permit its swallowing, these glands also protect the body by secreting the antibacterial agents lysozyme (breaks down bacterial capsules) and lactoferrin (binds iron) as well as the secretory immunoglobulin IgA

Front 161

major salivary glands

Back 161

paired, the parotid, submandibular and sublingual glands, are branched tubuloalveolar glands, has CT capsule that provides septa that subdivide the glands into lobes and lobules, produces 700-1000 cc of saliva a day, primary saliva produced by acinar cells/isotonic, secondary saliva (hypotonic) is modified primary saliva by striated ducts (remove Na+ and Cl- ions and add K+ and bicarbonate), parasympathetic is initiator saliva, sympathetic reduces blood flow

Front 162

minor salivary glands

Back 162

located in the mucosa and submucosa of the oral cavity, contribute only 5% of total daily saliva

Front 163

saliva

Back 163

composed of several proteins, enzymes, lactoferrin, bicarbonate (produced by striated duct)

Front 164

secretory portions of salivary glands

Back 164

composed of serous and/or mucous secretory cells arranged in acini (alveoli) or tubules that are couched by myoepithelial cells, whereas their ducts are highly branched and range from very small intercalated ducts to very large principle (terminal) ducts

Front 165

serous cells

Back 165

secrete both proteins and a considerable amount of polysaccharides, truncated pyramids, granules rich in ptyalin (salivary amylase), kallikrein, lactoferrin and lysozyme, round nuclei

Front 166

mucous cells

Back 166

flattened nuclei, have fewer mito, less extensive RER and greater Golgi (indicative of the greater carb component of their secretory product)

Front 167

myoepithelial cells (basket cells)

Back 167

share the basal laminae of the acinar cells, have long processes that envelop the secretory acinus and intercalated ducts, cytoplasmic processes which form desmosomal contacts with acinar and duct cells are rich in actin and myosin resembling smooth muscle cells, when they contract they press on the acinus facilitating release of the secretory products of the gland

Front 168

duct portion

Back 168

highly branched and range from very small intercalated ducts (where secretory acini are attached) to very large principal (terminal) ducts

Front 169

intercalated ducts

Back 169

composed of single layer of small cuboidal cells and some myoepithelial cells

Front 170

striated duct

Back 170

merging of several intercalated ducts, single layer of cuboidal to low columnar cells, the basolateral cell membranes have Na+-ATPase that pumps Na+ out of the cell into the CT, Na+ and Cl- are reabsorbed and the saliva becomes hypoosmotic, produces bicarbonate for the saliva (buffering agent of saliva)

Front 171

intralobular ducts

Back 171

merging of striated ducts, surrounded by more abundant CT, cuboidal-to-columnar epithelium

Front 172

interlobular ducts

Back 172

ducts arising from lobules unite to form this (PSCC), these unite to form intralobar then interlobar ducts (columnar stratified)

Front 173

terminal (principal) duct

Back 173

delivers saliva into the oral cavity, the last duct

Front 174

parotid gland

Back 174

largest of the salivary glands, produces only about 30% of the total salivary output, the saliva it produces is serous (but has a mucous component), has high levels of ptyalin and secretory IgA (inactivates antigens located in the oral cavity)

Front 175

submandibular gland

Back 175

produces 60% of the total salivary output, although it manufactures a mixed saliva, major portion is serous, longer striated ducts, histological sections display many cross-sectional profiles of these ducts, extensive capsule

Front 176

sublingual gland

Back 176

very small, composed mostly of mucous acini with serous demilunes and produces a mixed saliva (but mostly mucous), secrete lysozyme, has scant CT capsule and its duct system does not form a terminal duct

Front 177

salivon

Back 177

functional unit of a salivary gland

Front 178

pellicles

Back 178

protective film on the teeth formed from proteins in the saliva, provide a barrier against acids, retain moisture and regulate the adherence and activity of bacteria and yeast in the oral cavity

Front 179

benign pleomorphic adenoma

Back 179

a non-malignant salivary gland tumor, usually affects the parotid and submandibular glands

Front 180

mumps

Back 180

viral infections of the parotid gland (and occasionally other major salivary glands), painful disease that usually occurs in children, may result in sterility if affects adults

Front 181

pancreas

Back 181

produces exocrine (digestive juices) and endocrine secretions (hormones), has four regions (uncinate process, head, body and tail), flimsy CT that forms septa subdividing the gland into lobules

Front 182

endocrine components of the pancreas

Back 182

islets of Langerhans, are scattered among the exocrine secretory acini, Islets have five cell types, a greater number of islets are present in the tail than in the remaining regions, each islet is surrounded by reticular fibers

Front 183

cell types of the islets of langerhans

Back 183

not histologically distinguishable but immunocytochemical procedures allow them to be recognized
1. alpha cells-produce glucagon
2. beta cells-produce insulin
3. PP cells-produce pancreatic polypeptide, inhibits the exocrine secretions of the pancreas and also stimulates the release of enzymes by the gastric chief cells, depress the release of HCl by the parietal cells
4. G cells-manufacture gastrin, stimulates gastric release of HCl, gastric motility and emptying and the rate of cell division in gastric regenerative cells
5. delta cells-manufacture somatostatin, has paracrine and endocrine effects, inhibition of release of endocrine hormones by nearby alpha and beta cells, has an endocrine effect on smooth muscle cells of the GI tract, reducing the motility of these organs

Front 184

exocrine pancreas

Back 184

composed of acini whose lumen occupied by centroacinar cells (the beginning of the duct system of the pancreas), the acinar cells manufacture, store and release digestive enzymes

Front 185

acinus

Back 185

round and oval, made from 40 to 50 acinar cells, lumen is occupied by three or four aentroacinar cells, have receptors for CCK and Ach, release digestive enzymes

Front 186

centroacinar cells

Back 186

beginning of the duct system of the pancreas, manufacture a bicarbonate-rich buffer whose release is effected by the hormone secretin (produced by DNES cells of the small intestine) and possibly in concert with acetylcholine, have receptors for secretin and perhaps Ach

Front 187

duct system of the pancreas

Back 187

begins within the center of the acinus with the terminus of the intercalated ducts composed of pale, low cuboidal centroacinar cells, enters intralobular ducts which become interlobular ducts and eventually dump secretion into the main pancreatic duct which joins the common bile duct at the papilla of Vater

Front 188

digestive enzymes of the pancreas

Back 188

pancreatic amylae, pancreatic lipase, ribonuclease, deoxyribonuclease, and proenzymes chymotrypsinogen, procarboxypeptidase elastase, also manufacture trypsin inhbitor (protects the cell from intracellular activation of trypsin)

Front 189

cholecystokinin (pancreozymin)

Back 189

effects the release of the pancreatic enzymes, manufactured by DNES cells of the small intestine as well as by acetylcholine released by postganglionic parasympathetic fibers

Front 190

regulation of enzyme-rich and enzyme-poor secretions

Back 190

are regulated separately, and the two secretions may be released at different times or concomitantly

Front 191

acute pancreatitis

Back 191

digestive enzymes become activated within the acinar cytoplasm, often fatal, involve an inflammatory reaction, necrosis of the blood vessels, proteolysis of the pancreatic parenchyma and enzymatic destruction of adipose cells

Front 192

pancreatic cancer

Back 192

5th leading cause of mortality from all cancers, fewer than 50% survive at 1 year, fewer than 5% survive at 5 years, men are more susceptible, cigarette smokers have a 70% greater risk for development of pancreatic cancers than nonsmokers

Front 193

diabetes mellitus

Back 193

hyperglycemic metabolic disorder, can lead to circulatory disorders, renal failure, blindness, gangrene, stroke and MI
-Type I-children, 3 cardinal signs polydipsia, polyphagia and polyurea, insulin-dependent, can’t manufacture it
-Type II-adults greater than 40, 5 times more common than type I, non-insulin dependent, defective insulin receptors

Front 194

Verner-Morrison syndrome (pancreatic cholera)

Back 194

characterized by explosive, watery diarrhea that results in hypokalemia and hypochlorhydria, caused by the excessive manufacture and release of vasoactive intestinal peptide due to adenoma of the D1 cells that produce this hormone, tumors of D1 cells are freq. malignant

Front 195

liver

Back 195

has both endocrine and exocrine functions but the same cell is responsible for its exocrine and endocrine secretion

Front 196

hepatocyte

Back 196

liver cell, responsible for the formation of liver’s exocrine secretion (bile) and endocrine products, also detoxify toxins and excrete them in bile

Front 197

Gisson’s capsule

Back 197

liver’s connective tissue capsule, loosely attached except at the porta hepatis where it enters the liver forming a conduit for the blood and lymph vessels and bile ducts, CT elements are sparse, bulk of liver is composed of uniform parenchymal cells (hepatocytes)

Front 198

blood supply to the liver

Back 198

dual, receives oxygenated blood from the hepatic arteries (25%) and nutrient-rich blood via the portal vein (75%), both vessels enter the liver at the porta hepatis

Front 199

venous drainage of the liver

Back 199

blood leaves the liver at the posterior aspect of the organ through the hepatic veins, bile leaves the liver at the porta hepatis, by way of the hepatic ducts, to be delivered to the gallbladder for concentration and storage

Front 200

classical lobules

Back 200

hepatocytes form these hexagonal shaped structures whose boundaries in human liver can only be approximated

Front 201

portal area

Back 201

the region where three classical lobules join each other, houses slender branches of the hepatic artery, tributaries of the relatively large portal vein, interlobular bile ducts and lymph vessels

Front 202

central vein

Back 202

each lobule has one of these, receives blood from every sinusoid of that lobule, as the central vein leaves the lobule, it terminates in the sublobular vein which drains into the hepatic vein

Front 203

congestive heart failure

Back 203

valves are not present in the IVC and hepatic veins, an INC in central venous pressure (as in congestive heart failure) causes an enlargement of the liver due to blood engorgement

Front 204

portal hypertension

Back 204

an obstruction to blood flow in the liver during cirrhosis, together with failure of hepatocytes to produce plasma proteins, in particular albumin, results in portal hypertension, INC in hydrostatic pressure in the portal vein and its intrahepatic branches and fluid accumulated in the peritoneal cavitys (ascites), cirrhosis may develop following chronic hepatitis or alcoholic liver disease

Front 205

carcinoma of the pancreas

Back 205

carcinoma of the head of the pancreas obstructs by compression the outflow of bile through the ampullary region

Front 206

classical liver lobule

Back 206

first to be defined histologically, blood flows from the periphery to the center of the lobule into the central vein, bile manufactured by liver cells enter into small intercellular spaces (bile canaliculi) located between hepatocytes and flows to the periphery of the lobule to the interlobular bile ducts of the portal areas, contains a central venule and components of the portal triad at all the angles

Front 207

portal lobule

Back 207

the triangular region whose center is the portal area and whose periphery is bounded by imaginary straight lines connecting the three surrounding central veins, includes portions of those lobules whose bile canaliculi drain into the same bile duct, the boundaries of a portal lobule are the central veins of three classic lobules, the center of the portal lobule is the bile duct collecting the bile from all canaliculi

Front 208

hepatic acinus (acinus of Parraport) (liver acinus)

Back 208

it is viewed as three poorly defined, concentric regions of hepatic parenchyma surrounding a distributing artery in the center, the outermost layer (zone 3) extends as far as the central vein and is the most oxygen-poor of the three zones, the remaining regions is equally divided into two zones (1 and 2), zone 1 is the richest in oxygen

Front 209

zone 1 (periportal)

Back 209

hepatocytes synthesize actively glycogen and plasma proteins, oxygen concentration in sinusoidal blood is high

Front 210

zone 2

Back 210

is an intermediate zone

Front 211

zone 3 (central venous drainage)

Back 211

is the region where oxygen concentration is the poorest, zone III has a role in detoxification, hepatocytes are susceptible to damage caused by hypoxia

Front 212

perilobular region

Back 212

cells in this region are the first to alter the incoming blood and the first to be affected by it, after feeding, first to receive incoming glucose and to store it as glycogen, in the fasting state, these cells would be the first to respond to glucose-poor blood by breaking down glycogen and releasing glucose, have abundance of extrahepatic hormones, key glucose-liberating and fatty-acid-oxidation enzymes

Front 213

middle region

Back 213

the next to responds to blood, would not respond to the fasting condition until all the glycogen in the perilobular region was all used up

Front 214

centrolobular region

Back 214

see portal vein blood that has already been altered by cells in previous regions, have abundance of key glycolysis enzymes and fatty-acid-synthesizing enzymes

Front 215

liver functions

Back 215

most functions of liver performed by hepatocytes, metabolize the end products of absorption from the alimentary canal, store them as inclusion products and release them in response to hormonal and nervous signals, also detoxify drugs and toxins and transfer secretory IgA from the space of Disse, Kupfer cells are present to phagocytose blood-borne foreign particulate matter and defunct erythrocytes, remove chylomicrons from the space of Disse and degrade them into fatty acids and glycerol, maintain blood glucose levels, deaminate amino acids and form urea, synthesize many blood proteins, store vita A in the greatest amount

Front 216

bile

Back 216

contains bile salts, bilirubin glucuronide (bile pigment), phospholipids, lecithin, cholesterol, plasma electrolytes and IgA, it emulsifies fat, eliminates approx. 80% of the cholesterol synthesized by the liver and excretes blood-borne waste products such as bilirubin

Front 217

microsomal mixed-function oxidases

Back 217

are in hepatocytes, inactivate drugs (barbituates and antibiotics) and toxisn, usually inactivated in the cisterna of the SER by methylation, conjugation, or oxidation, can also occur in peroxisomes rather than in the SER,

Front 218

secretory IgA

Back 218

hepatocytes complex IgA with secretory components to secrete this into the bile canaliculi

Front 219

Kupfer cells

Back 219

recognize and endocytose blood-borne microorganisms and also remove cellular debris and defunct erythrocytes from the blood

Front 220

space of Disse

Back 220

separates the basolateral domain of the hepatocyte from the blood circulating in the hepatic sinusoid, the space of Disse contains type I, III, and IV collagen fibers, protein absorption and secretion take place across the narrow space of Disse

Front 221

space of Mall

Back 221

found at the periphery of the hepatic lobule, is continuous with the space of Disse, the Space of Mall is drained by lymphatic vessels piercing the liming plate, lymphatic vessels surround the blood vessels and bile ductules in the portal space

Front 222

canal of Hering

Back 222

the terminal point of the network of bile canalicular trenches found on the hepatocyte surfaces (except that facing the space of Disse), the canal of Hering is located at the periphery of the haptic lobule, is lined by a squamous-to-cuboidal simple epithelium and connects with the bile ducutles in the portal space after perforating the limiting plate

Front 223

portal space (canal, area, or tract)

Back 223

houses the portal triad, lymphatic vessels and nerve fibers

Front 224

plasma membrane of hepatocytes

Back 224

lateral and sinusoidal domains

Front 225

lateral (apical) domain

Back 225

form elaborate, intercellular spaces, 1 to 2 micrometers in diameter, bile canaliculi, that conduct bile between hepatocytes to the periphery of the classical lobules

Front 226

singusoidal (basolateral) domain

Back 226

have microvilli, which project into the space of Disse, INC SA by a factor of 6, facilitating the exchange of material between the hepatocyte and the plasma in the perisinusoidal space

Front 227

cell composition of hepatocytes

Back 227

have an abundance of free ribosomes, RER and Golgi, each cell houses several sets of Golgi, located near bile canaliculi, as many as 2000 mito, cells in zone 3 have nearly twice as many mito and rich SER (INC in presence of certain drugs and toxins), zone 1 hace smaller ones, also have many endosomes, lysosomes, and peroxisomes

Front 228

hepatic sinusoids

Back 228

lined by two cell types, discontinuous endothelial cells and phagocytic Kupfer cells

Front 229

bile canaliculus

Back 229

an extracellular canal between adjacent hepatocytes, surface displays microvilli, bile released into the canaliculus is drained by an intralobular ducutle (colangiole) that converges to the canal of Hering near the portal space, canal of Hering carries the bile to the bile ducutles one of the three components of the portal space

Front 230

RER of hepatocytes

Back 230

involved in synthesis of plasma proteins, albumin (maintain oncotic pressure), coagulation factors (fibrinogen and prothrombin in particular) and binding proteins for hormones and growth factors in blood coagulation

Front 231

SER of hepatocytes

Back 231

highly developed and is always associated with clusters of glycogen molecules forming typical rosette-like inclusions, stored glycogen in hepatocytes represents a glucose reserve for the maintenance of sugar concentrations in blood, glycogen is also stored in muscle, detox role

Front 232

hepatocytes

Back 232

never come in contact with blood

Front 233

stellate cells

Back 233

store fat soluble vita A, produce collagen fibers

Front 234

cirrhosis

Back 234

a diffuse condition of the liver associated with progressive fibrosis, the perisinusoidal hepatic stellate cells transform into myofibroblasts and become the main collagen-producing cells of the cirrhotic liver

Front 235

cytokines of the liver

Back 235

produced by hepatocytes, Kupferr cells and infiltrating lymphocytes in the space of Disse, stimulate the production of type I collagen by hepatic stellate cells, deposit of type I collagen in the space of Disse results in fibrosis that alters the flow of portal venous blood into the hepatic sinusoids

Front 236

limiting plate

Back 236

surrounds the portal space, brances of vessels and biliary ductules perforate the limiting plate to enter or exit the hepatic lobule

Front 237

hepatic plate

Back 237

hepatocytes are arranged in plates one cell thick, branch or anastomose leaving a space containing venous sinusoids, rows of hepatocytes representing sections of plates converge at the central vein

Front 238

functions of the gallbladder

Back 238

1. concentration and storage of bile between meals
2. release of bile by contraction of the muscularis in reponse to CCD stimulation and neural stimuli, together relaxation of the sphincter of Oddi
3. regulation of hydrostatic pressure within the biliary tract

Front 239

structure of the gallbladder

Back 239

wall of the gallbladder comprises of four layers, epithelium, lamina propria, smooth muscle and serosa/adventitia, mucosa is highly folded, lined by simple columnar epithelium composed of clear cells and brush cells, lamina propria is vascularized loose CT well endowed with elastic and collagen fibers, thin smooth muscle layer composed of obliquely oriented fibers

Front 240

cholestasis

Back 240

defines the impaired formation and excretion of the bile at the level of the hepatocyte or a structural or mechanical perturbation in the excretion of bile, detected by the presence of bilirubin in the blood, elevation in serum of alkaline phosphatase, and radiologic examination (radiopaque gallstones)

Front 241

gallstones (cholelithiasis)

Back 241

more common in women, 4th decade of life, 20% of all women and 8% of all men, if entrapped in the cystic or common hepatic ducts they can cause excrutiating pain, 80% composed of cholesterol, remainder are formed from calcium salt, calcium bilirubinate or a combination of cholesterol and calcificed bilirubinate

Front 242

zone 3 and necrosis

Back 242

this zone has the lowest oxygen levels and is the most susceptible to necrosis in case of severe liver injury

Front 243

Wilson’s disease

Back 243

hereditary condition in which the liver down not eliminate copper by transferring it into bile, copper accumulates in the eyes, appear as green to gold rings there

Front 244

jaundice

Back 244

yellowish discoloration of the skin, results from excessively high levels of free or conjugated bilirubin

Front 245

obstructive jaundice

Back 245

due to a decrease in bilirubin conjugation due to either hepatocyte malfunction or obstruction of the bile ductes

Front 246

hemolytic jaundice

Back 246

due to INC hemolysis of erythrocytes producing so much free bilirubin that hepatocytes cannot eliminate it rapidly enough

Front 247

drug tolerance

Back 247

DEC effectiveness of drugs (such as barbituates) due to long-term use, due to hypertrophy of the SER complement of hepatocytes and a concomitant INC in their MFO, hepatocytes do become more efficient in detoxifying other drugs and toxins

Front 248

endocrine system

Back 248

produces a slow, diffuse effect via hormones (vs. very rapid in the ANS), but it does interact with the ANS to modulate metabolic acitivites of the body, consists of ductless glands

Front 249

endocrine glands

Back 249

pituitary gland, thyroid gland, parathyroid gland and suprarenal gland

Front 250

hormone

Back 250

a substance (chemical messenger) released into either blood or lymph, or extracellular space which has a specific effect, in this sense, hormones thought to be an extension of neural transmission, most hormones in blood are bound to protein carriers and are active, circulate in the blood and are in over supply

Front 251

categories of hormones

Back 251

1. steroid/steroids and thyroid hormones are lipid soluble-diffuse through cell membrane to intracellular receptors, alter the rate of gene transcription, some bind to surface receptors and in that way mediate response
2. and 3, proteins/polypeptides and amino acid analogs-mostly water soluble, bind to hormone receptors in cell membrane, act via second messengers like cAMP, cGMP, calcium ions, and sodium ions

Front 252

types of hormonal secretion

Back 252

autrocrine, paracrine, endocrine, synaptic

Front 253

pituitary gland (hypophysis)

Back 253

composed of portions derived from oral ectoderm and from neural ectoderm, produces hormones that regulate growth, metabolism and reproduction, composed of an anterior lobe (adenohypophysis) and posterior lobe (neurohypophysis) held in and encapsulated in a single gland, secretes 9 hormones

Front 254

hormones of the hypophysis

Back 254

1. pars distalis-somatotropin, prolactin, adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), interstitial cell-stimulating hormone (ICSH) in men, thyroid stimulating hormone (TSH)
2. pars nervosa-oxytocin, vasopressin (ADH)

Front 255

derivation of adenohypophysis (anterior lobe)

Back 255

derived from oral ectoderm (Rathke’s pouch), further subdivided into the pars tuberalis, pars distalis and pars intermedia

Front 256

derivation of neurohypophysis (posterior lobe)

Back 256

derived from neural ectoderm (downgrowth from diencephalon), subdivided into the infundibulum and pars nervosa

Front 257

pituitary and nervous system

Back 257

connected to the brain by neural pathways, also rich vascular supply from vessels that supply the brain attesting to the intercoordination of the two systems in maintaining a physiological balance

Front 258

hypothalamus and the nervous system

Back 258

CNS also controls the hypothalamus, receive info regarding plasma circulating levels of electrolytes and hormones, hypothalamus is the brain center for the maintenance of homeostasis

Front 259

somatotropin

Back 259

GH, affects adipose tissue (elevation of free fatty acids), muscle (hyperglycemia) and bone (growth), acidophil, released by pars distalis, most common acidophilo, stimulated by SRH and inhibited by somatostatin

Front 260

prolactin

Back 260

mammotrophin, acidophil, released by pars distalis, effects mammary gland (milk secretion), stimulated by PRH and inhibited by PIH, estrogen, and progesterone

Front 261

ACTH

Back 261

corticotroph, released by pars distalis, a basophile, effects the adrenal cortex for secretion, most common basophile, stimulated by CRH

Front 262

FSH

Back 262

gonadotrophin, basophile, released by pars tuberalis, has an effect on follicular development and estrogen secretion and spermatogenesis, secretion is stimulated by LHRH and inhibited by various hormones produced by the ovaries and testis

Front 263

LH

Back 263

gonadotroph, basophile, released by pars tuberalis, has an effect on the testis for androgen secretion and on the ovary for ovulation and progesterone secretion, secretion is stimulated by LHRH and inhibited by various hormones produced by the ovaries and testis

Front 264

TSH

Back 264

thyrotroph, basophile, released by pars distalis, has an effect on the thyroid for secretion, can be distinguished by their small secretory granules, secretion is stimulated by TRH and inhibited by the presence of thyroxine and tri-iodothyronine

Front 265

oxytocin

Back 265

released by the pars nervosa, paraventricular nucleus, induce labor, control postpartum bleeding, has an effect on the uterus (contraction) and mammary gland (myoepithelial contraction, milk letdown)

Front 266

ADH

Back 266

supraoptic nuclei, water resorption in collecting tubules + vasoconstriction

Front 267

blood supply and control of secretion of the hypophysis

Back 267

provided from two pairs of vessels that arise form the internal carotid artery, superior hypophyseal arteries (supply the pars tuberalis and infundibulum) and inferior hypophyseal arteries (supply the posterior lobe, and a few branches to the anterior lobe)

Front 268

blood supply to the adenohypophysis

Back 268

there is no direct blood supply to the adenohypophysis, the anterior pituitary connected to hypothalamus by neuroendocrine link, the hypophyseal portal veins join the primary capillary network in the infundibulum to the secondary capillary network in the pars distalis, the hypophyseal portal system carries releasing factors from the hypothalamus to the pars distalis (regulate secretion of various anterior pituitary hormones via hypothalamus)

Front 269

adenohypophysis

Back 269

epithelial cells surrounded by extensive sinusoids, 4 cell types present histologically (acidophils, basophils, chromophobes and folliculostellate cells)

Front 270

acidophiles

Back 270

granules stain orang-red with eosin, are of two varietie: somatotrophs and mammotrophs, most abundant cells in the pars distalis

Front 271

basophiles

Back 271

granules stain blue with basic dyes, of three varieties: corticotrophs, thyrotrophs, and gonadotrophs

Front 272

chromophobes

Back 272

degranulated acidophils and basophils, have very little cytoplasm and do not take up stain readily, represent nonspecific stem cells or degranulated chromophils

Front 273

folliculostellate cell

Back 273

cellular stroma, unclear function, have long processes that form gap junctions with those of other folliculostellate cells

Front 274

pars distalis

Back 274

anterior lobe, consists of chromophils (have an affinity for dyes, further subdivided into acido- and baso-phils) and chromophobes (no affinity for dyes)

Front 275

pars intermedia

Back 275

lies between the pars distalis and pars nervosa and contains cysts that are remnants of Rathke’s pouch, characterized by many cuboidal cell-lined, colloid-containing cysts, may sometimes house basophile cords, responsible for production of prolactin release factor (PRH)

Front 276

pars tuberalis

Back 276

surrounds the hypophyseal stalk and is composed of cuboidal to low-columnar basophilic cells, highly vascularized by the hypophyseal portal system, no secretions but some cells do contain FSH and LH

Front 277

neurohypophysis

Back 277

posterior pituitary gland, constituted of the median eminence, the infundibulum and the pars nervosa, unmyelinated axons and nerve endings of hypothalamic neurosecretory neurons, supported by pituicytes (glial-like cells, though to help in the release of oxytocin and vasopressin), swellings at the distal ends of hypothalamohypophysial axons (Herring bodies), synthesize two main hormones and neurophysin (protein carrier), complex transported via the hypothalamohypophysial tract to the pars nervosa, crossover occurs in the hypothalamic nuclei

Front 278

pituicytes

Back 278

occupy about 25% of the volume of the pars nervosa, contain lipid droplets, lipochrome pigment, and intermediate filaments

Front 279

Herring bodies

Back 279

site for storage of oxytocin and vasopressin, accumulations of neurosecretory granules, stain blue-black at the termini and through the length of the axons

Front 280

hypothalamohypopyseal tract

Back 280

axons of neurosecretory cells of supraoptic and paraventricular nuclei extend into the posterior pituitary as this tract

Front 281

pars nervosa

Back 281

receives terminal of the neurosecretory hyophalamohypophyseal tract, not an endocrine gland, distal terminals of the axons end here and store the neurosecretions that are produced by their cell bodies located in the hypothalamus

Front 282

pituitary adenomas

Back 282

common tumors of the anterior pituitary gland, their growth and enlargement may suppress hormonal production in other secretory cells of the pars distalis, adenomas may erode surrounding bone and other neural tissue

Front 283

diabetes insipidus

Back 283

may be caused by lesions in the hypothalamus or pars nervosa that reduce the production of ADH, leads to renal dysfunction, which leads to inadequate water resorption by the kidneys, resulting in polyuria and dehydration

Front 284

thyroid gland

Back 284

1st endocrine gland to appear in embryonic development, produces T4 (thyroxine) and T3 (triiodothyronine) (which are both under the influence of TSH) and secretes calcitonin, located in the anterior portion of the neck, composed of right and left lobe connected by an isthmus

Front 285

structure of the thyroid gland

Back 285

encapsulated/CT extending in to form lobules, septa provide conduit for blood vessels, lymphatic vessels and nerve fibers, structural unit: follicles filled with colloid (T3 and T4 stored in here), epithelium surrounding a lumen filled with colloidal material (iodinated thryoglobulin) enclosed by a basal lamina, composed of 2 cell types, colloid is bound to thryoglobulin (secretory glycoprotein), when the hormone is to be released, thyroglobulin is endocytosed and the hormones are cleaved from it

Front 286

cell types of the thyroid gland

Back 286

1. follicular cells-embryonic origin of endoderm, target cells for TSH, responsible for production of thyroglobulin and release of T3 and T4
2. parafollicular cells (C cells)-embryonic origin of neural crest, produces calcitonin (thyrocalcitonin) which decreases Ca2+ levels

Front 287

follicular cells

Back 287

squamous to low-columnar, tallest when stimulated, synthesize thyroglobulin, responsible for trapping iodide (I-), extracellular iodination of thyroglobulin in follicle, storage of iodinated thyroglobulin in the lumen for up to 3 months, uptake of I2 thyroglobulin controlled by TSH, hydrolysis of I2 to T3 and T4 regulates tissue metabolism, T4 (90%) and T3 (10%)

Front 288

what happens when there is a high demand for thyroid hormone

Back 288

follicular cells extend pseudopods into the follicles to envelop and absorb colloid

Front 289

synthesis of thyroid hormones

Back 289

regulated by iodide levels and by TSH binding to TSH receptors of follicular cells, thyroblobulin is synthesized in the RER and glycosylated in the RER and Golgi then released into the colloid and stored in the lumen of the follicle, iodide is brought in through sodium/iodide symporters, oxidized by thyroid peroxidase, this activated iodide enters the colloid and iodinates tyrosine residues of thyroglobulin forming monoiodinated tyrosine (MIT) and diiodinated tyrosine (DIT), then couple MITs and DITs to form T3 and T4

Front 290

release of thyroid hormones

Back 290

TSH stimulates follicular cells of the thyroid gland to release T3 and T4 into the bloodstream, binding of TSH facilitates formation of filopodia at the apical cell membrane, resulting in endocytosis of aliqutos of the colloid, lysosomes and colloid droplets fuse causing digestion by enzymes, this releases T3 or T4 which can leave the cell

Front 291

parafollicular cells (clear cells)

Back 291

do not reach the lumen of the follicle, more rapidly acting, APUD cell, enteroendocrine cell, part of the DNES, located usually in clusters among the follicular cells, do not extend into the lumen, produces calcitonin (thyrocalcitonin, regulated by a feedback mechanism with parathyroid hormone), decreases Ca2+ levels reduces osteoclast ruffling, reduces osteoclast #s, promotes excretion of Ca2+ and phosphate from kidneys

Front 292

histological differentiation of C cell

Back 292

can be distinguished from surrounding follicular cells by its pale cytoplasm, can also be differentiated by immunocytochemistyr using an antibody to calcitonin and electron microscopy to visualize calcitonin-containing cytoplasmic granules

Front 293

Grave’s disease

Back 293

characterized by hyperplasia of the follicular cells, INC the size of the thyroid gland two to three times above normal, hyperthyroidism (excess thyroid hormone production), exophthalmos (protrusion of the eyeballs), most commonly caused by IgG binding to TSH receptors

Front 294

simple goiter

Back 294

caused by insufficient intake of iodine causing the thyroid gland to enlarge, not associated with hyper or hypothyroidism

Front 295

hypothyroidism

Back 295

characterized by such conditions as fatigue, sleeping for up to 14 to 16 hours, muscular sluggishness, slowed heart rate, constipation and loss of hair growth, may develop myxedema (bagginess under the eyes and swollen face)

Front 296

cretinism

Back 296

extreme form of hypothyroidism occurring in fetal life through childhood that is characterized by failure of growth and mental retardation

Front 297

parathyroid gland

Back 297

comes from mesoderm, two cell types, principal (chief) cells and oxyphils cells, regulates blood calcium levels, have CT capsule which turn into septa

Front 298

development of parathyroid gland

Back 298

develop from the third and fourth pharyngeal pouches during embryogenesis, the ones from the third descend with the thyroid and become inferior, those that develop from the 4th descend a short distance to become superior parathyroid glands

Front 299

principal (chief) cells

Back 299

synthesize parathyroid hormone (PTH), causes INC in Ca2+ levels, binds to receptors on osteoblasts, releases osteolcast-stimulating factor, paler and smaller cell, preproparathyroid hormone is synthesized on ribosomes of the RER, cleaved to form proparathyroid hormone then cleaved again (in the golgi) to form PTH

Front 300

PTH and calcium control

Back 300

can also prevent loss of calcium in the urine, also controls the rate of calcium uptake in the GI tract by indirectly regulating the production of Vita D which is necessary for intestinal uptake of Ca2+

Front 301

oxyphil cells

Back 301

larger than principal cells, possess many mito, appear at puberty/increase with age, function unknown, believed to be the inactive phase of chief cells

Front 302

primary hyperparathyroidism

Back 302

may be caused by a tumor in one of the parathyroid glands, marked by high blood calcium, low blood phosphate, loss of bone mineral

Front 303

secondary hyperparathyroidism

Back 303

may develop with rickets because calcium cannot be absorbed from the intestines owing to vita D deficiency, low calcium in blood

Front 304

hypoparathyroidism

Back 304

results from deficiency in secretion of PTH commonly caused by injury of the parathyroid glands, marked by low blood calcium levels, retention of bone calcium and INC phosphate resorption in the kidney, symptoms include numbness and tingling

Front 305

ectopic sites of adrenal gland

Back 305

cortical and medullary tissue of adrenal gland are sometimes found along the abdominal aorta just superior to its bifurcation into the common iliac arteries

Front 306

suprarenal (adreal) glands

Back 306

produce two different groups of hormones (steroids and catecholamines), right and left not mirror images of each other (right is pyramid shaped and on the top of right kidney, left is more crescent shaped and more so on medial border of the left kidney), is encapsulated, composed of a cortex and medulla

Front 307

adrenal cortex

Back 307

80-90% of the organ, derived from mesoderm, produce steroid hormones (mineralcorticoids, glucocorticoids, androgens) without storing them, all synthesized from cholesterol of low density lipoprotein fame, controlled by ACTH and kidney, columns of cells separated by sinusoids, consists of three zones that produce three classes of steroids

Front 308

zones of the adrenal cortex

Back 308

1. zona glomerulosa (ZG)-secrete mineralcorticoids, mainly aldosterone but also deoxycorticosterone, regulated by renin-angiotensin system (angiotensisn II) and ACTH, regenerative zone of adrenal cortex
2. zona fasciculata (ZF)-thick middle zone, form parallel cords of cells separated by sinusoid, cells are larger and contain lipid droplets, secrete glucocorticoids (mainly corticosterone and cortisol, controlled by ACTH, accounts for up to 80% of organ volume
3. zona reticularis (ZR)-inner most layer, often contain lipofuscin granules, cells in anastamosing cords, secrete mainly androgenic steroids (dehydroepiandrosterone, androstenedione and some glucocoritcoids), controlled by ACTH, accounts for about 7% of gland volume

Front 309

mineralcorticoids

Back 309

function in controlling fluid and electrolyte balance in the body by affecting the function of the renal tubules, specifically the distal convoluted tubules, target the gastic mucosia, salivary glands and sweat glands, stimulate absorption of Na+

Front 310

glucocorticoids

Back 310

function in the control of carbohydrates, fat and protein metabolism in liver, also anti-inflammatory responses by inhibiting macrophage and leukocyte infiltration at sites of inflammation, controlled by negative feedback mechanism, if high, the CRH (corticotrophin-releasing hormone) is inhibited which in turn inhibits corticotrophs

Front 311

dehydroepiandrosterone and androstenedione

Back 311

weak, masculinizing hormones with negligible effects under normal conditions

Front 312

adrenal medulla

Back 312

derived from neural crest, produce catecholamines (epinephrine (80%) and norepinephrine (20%), innervatred by preganglionic sympathetic fibers, contains large vascular sinusoids and blood vessels, two types of cells

Front 313

cell types of the adrenal medulla

Back 313

1. chromaffin cells-modified postganglionic neurons that have a secretory function, lack dendrites and axons, 80% epinephrine, INC HR and CO, NC in BP, 20% norepinephrine, INC in BP through vasoconstriction, chromaffin cells store opioid peptides (ie enkephalins) that mediate analgesic, secreted in response to preganglionic sympathetic (cholinergic) splanchnic nerves
2. postganglionic sympathetic ganglion cells in connective tissue-

Front 314

identifying catecholamins

Back 314

turn deep brown when exposed to chromiffin salts, indicates that the cells contain catecholamines

Front 315

chromagranins

Back 315

proteins that are believed to bind epinephrine and norepinephrine

Front 316

blood supply to the adrenal gland

Back 316

1. to cortex-from the vascular bed of the capsular arteries, form sinusoids which travel through cortex and drain into medulla
2. to medulla-has dual blood supply, directly from capsular arterioles (long cortical arteries) or from the cortical sinusoids (capillary beds), dual blood supply required for synthesis of epinephrine

Front 317

capsular plexus

Back 317

formed by the superior and middle adrenal arteries, supply the three zones of the cortex, fenestrated cortical capillaries derive from these blood vessels

Front 318

fenestrated cortical capillaries

Back 318

percolate through the zonae glomerulosa and fasciculate and form a network within the zona reticularis before entering the medulla

Front 319

medullary artery

Back 319

derive from the inferior adrenal artery, enters the cortex within a connective tissue trabecula and supplies blood directly to the adrenal medulla, bypases the cortex without branching

Front 320

medullary venous sinuses

Back 320

forms from the joining of the medullary artery with branches from the cortical capillaries, thus medulla has two blood supplies, one from the cortical capillaries and the other from the medullary artery

Front 321

conversion of norepinephrine to epinephrine

Back 321

by chromaffin cells, dependent on phenylethanolamine N-methyltransferase (PNMT), an enzyme activated by cortisol transported by the cortical capillaries to the medullary venous sinuses

Front 322

pheochromocytomas (paraganglia)

Back 322

secreting tumors

Front 323

Addison’s disease

Back 323

characterized by DEC secretion of the adrenocortical hormones as a result of destruction of the suprarenal cortex, autoimmune

Front 324

Cushing’s disease (hyperadrenocorticism)

Back 324

caused by small tumors in the basophils of the anterior pituitary gland, lead to an INC in the output of ACTH, causes enlargement of the suprarenal glands and hypertrophy of the suprarenal cortex, resulting in overproduction of cortisol, obese patients and exhibit osteoporosis

Front 325

pineal gland

Back 325

derived from neuroectoderm, has leptomeningeal coverings, lies in the midline, two cell types, can act as a radiological landmark, responsive to diurnal light and dark periods and is thought to influence gonadal activity, covered by pia matter forming a capsule from which septa extend, divide the pineal gland into incomplete lobules, projection from the roof of the diencephalon

Front 326

cell types of the pineal gland

Back 326

1. pinealoctyes-melatonin produced at night and serotonin during the day
2. neuroglial (interstitial) cells-melatonin levels high in children (pre-puberty), melatonin levels decline with the onset of puberty

Front 327

melatonin

Back 327

synthesized from tryptophan by pinealocytes, released at night, inhibits the release of GH and gonadotropin by the hypophysis and hypothalamus, induces the feeling of sleepiness

Front 328

brain sand

Back 328

corpora arenacea, increases with age, calcium deposits, found in the extracellular space, typical histological feature of the pineal gland

Front 329

nerve input to the pineal gland

Back 329

from the postganglionic sympathetic nerve fibers derived from the superior cervical ganglion

Front 330

kidney functions

Back 330

1. filtration-kidney glomeruli
2. selective resorption and excretion-kidney tubular system
3. regulates blood pressure via renin-angiotensin
4. produces erythropoietin, renin and prostaglandins
5. activates enzyme involved in calcium metabolism
6. conserves salts, glucose, proteins and water as well as additional material essential for proper health

Front 331

kidney structure

Back 331

encapsulated, consists of a cortex and medulla, has a concave region (hilum) where the ureter, renal vein, renal artery and lymph vessels pierce the kidney, embedded in perirenal fat

Front 332

kidney cortex

Back 332

contains renal corpuscles (red, dot-like granules), cortical labyrinth (convoluted tubules) and medullary rays

Front 333

kidney medulla

Back 333

1. renal pyramids-bases form the corticomedullary border, represents a lobe of the kidney
2. renal papilla-drains up to 20 collecting ducts (ducts of Bellini)

Front 334

renal lobe

Back 334

a renal pyramid with associated cortical arch

Front 335

medullary ray

Back 335

is a group of collecting tubules that extend from the medulla into the cortex

Front 336

renal lobule

Back 336

a medullary ray with the cortex surrounding it

Front 337

cortical arch

Back 337

portion of the cortex overlying the base of each pyramid

Front 338

lobated kidney

Back 338

lobes of kidney are accentuated by deep clefts in fetal development, if retained following infancy leads to lobated kidneys

Front 339

polycystic kidney disease

Back 339

presents varied morphological features according to the severity of the affliction, it involves the appearance of thin-walled cysts on and in the kidneys

Front 340

nephron

Back 340

glomerulus and kidney tubules (PCT, Loop of Henle, DCT), each kidney has more than one million nephrons, filtration, excretion and reabosorption

Front 341

uriniferous tubules

Back 341

nephron and collecting duct, functional unit of the kidney, epithelial in nature, has an intervening lamina propria

Front 342

collecting tubule

Back 342

drains numerous nephrons, and multiple collecting tubules join in the deeper aspect of the medulla to form larger and larger ducts

Front 343

ducts of Bellini

Back 343

the largest of the ducts (composed of multiple collecting tubules), perforate the renal papilla at the area cribrosa

Front 344

cortical nephrons

Back 344

the renal corpuscle of each cortical nephron is located in the outer region of the cortex, its loop of Henle is short and does not enter the medulla, the efferent glomerular arteriole branches into a peritubular capillary network, surrounding the convoluted segments of its own and adjacent nephrons

Front 345

juxtamedullary nephron

Back 345

the renal corpuscle of each juxtamedullary nephron is located in the cortex region adjacent to the medulla, its loop of Henle is longer and extends deep into the medulla, the efferent glomerular arteriole branches into vascular loops called the vasa recta, the vasa recta descend into the medulla and form a capillary network surrounding the collecting ducts and limbs of the loop of Henle

Front 346

vascularization of the kidney

Back 346

1. renal artery gives rise to segmental arteries (no anastamoses)
2. segmental arteries give rise to lobar arteries (one for each lobe)
3. lobar arteries give rise to interlobar arteries (travel between renal pyramids)
4. the interlobar artery gives rise to arcuate arteries (arc over the base of the renal pyramid)
5. arcuate arteries give rise to interlobular arteries (intersticies between two lobules)
6. interlobular arteries give rise to afferent glomerular arterioles (supply the glomerulus)
7. efferent glomerular arterioles (drain the glomerulus) close to the subcapsular region give rise to the peritubular capillary network, those close to the juxtamedullary region give rise to vasa recta
8. the arterial blood supply to the cortex is terminal (no anastomoses)

Front 347

arterial vs. venous supply to the kidney

Back 347

1. in general a capillary network is interposed between an arteriole and a venule
2. in the kidney, an arteriole is interposed between two capillary networks, an afferent arteriole gives rise to a mass of capillaries (the glomerulus), these capillaries coalesce to form an efferent arteriole, which gives rise to capillary networks (peritubular capillary network and the vasa recta) surrounding the nephrons
3. in the liver and hypophysis, veins feed into an extensive capillary or sinusoid network draining into a vein, this distribution is called the venous portal system

Front 348

renal corpuscle

Back 348

composed of a tuft of capillaries, the glomerulus, surrounded by Bowman’s capsule, composed of a tuft of glomerular capillaries that grows into the blind end of a nephron, covered by visceral layer of epithelium (podocytes) which function in the production of a glomerular filtrate and supportive mesangial cells

Front 349

Bowman’s capsule

Back 349

the proximal bulb-like expansion of the nephron is called Bowman’s capsule, retains a parietal layer of simple squamous epithelium

Front 350

bowman’s space

Back 350

where the glomerular filtrate is released into, space inside Bowman’s capsule

Front 351

urinary pole

Back 351

is continuous with the PCT, region of continuation between the renal corpuscle and PCT, drains Bowman’s space

Front 352

vascular pole

Back 352

where the vessels supplying and draining the glomerulus enter and exit Bowman’s capsule, afferent and efferent arterioles possess modified smooth muscle cells in the tunica media (juxtaglomerular (JG) cells), extraglomerular mesangial cells are found between the afferent and efferent arterioles

Front 353

macula densa

Back 353

is an area of specialized cells within the DCT that is in contact with both the afferent and efferent arterioles, in contact with extraglomerular mesangial cells

Front 354

components of the juxtaglomerula apparatus

Back 354

the macula densa, the extraglomerular mesangial cells, the JG cells

Front 355

glomerulus

Back 355

composed of tufts of fenestrated capillaries supplied by the afferent glomerular arteriole and drained by the efferent glomerular arteriole, in intimate contact with the visceral layer of Bowman’s capsule

Front 356

mesangial cells

Back 356

connective tissue component of glomerulus, phagocytic (resorption of the basal lamina), provide physical support, replace normal connective tissue cells, two types, extraglomerular (located at the vascular pole) and intraglomerular (situated within the renal corpuscle), may be contractile and provide support to the capillaries of the glomerulus

Front 357

fenestrations of capillaries

Back 357

pores are large and act as a barrier only to formed elements of the blood and to macromolecules whose effectibe diameter exceeds the size of the fenestrae

Front 358

intraglomerular mesangial cells

Back 358

probably phagocytic and function in resorption of the basal lamina

Front 359

basal lamina of the glomerulus

Back 359

composed of three layers
1. lamina rara interna (capillary side), contain laminin, fibronectin, located in the internal side of the lamina densa, between the endothelial cells of the capillary and the lamina densa
2. lamina densa (very thick), middle layer, composed of type IV collagen
3. lamina rara externa (visceral layer side) , contain laminin, fibronectin, located in the internal side of the lamina densa, between the lamina densa and the visceral layer of Bowman’s capsule

Front 360

visceral layer of Bowman’s capsule

Back 360

composed of podocytes (primary processes (long cytoplasmic processes), each primary process has multiple secondary processes called pedicles (envelop the glomerular capillaries)), highly modified to perform a filtering function

Front 361

pedicels

Back 361

lie on the lamina rara externa, interdigitate forming up filtration slits covered by a thin (6 nm thick) slit diaphragm

Front 362

Alport’s syndrome

Back 362

caused by mutations in the alpha3 and alpha4 chains of type IV collagen, is an autosomal recessive disorder distinguished by loss of hearing, vision problems and nephritis, freq. suffer from kidney failure

Front 363

glomerular filtration

Back 363

1. fluid leaving the glomerular capillaries through the fenestrae is filtered by the basal lamina
2. the lamina densa traps larger molecules (>69,000 Da)
3. laminae rara impede the passage of negatively charged molecules and molecules that are incapable of deformation (do to the presence of proteoglycans rich in heparin sulfate)
4. the fluid that penetrates the lamina densa and enters Bowman’s space is the glomerular ultrafiltrate
5. because the basal lamina traps larger macromolecules, it would become clogged were it not continuously phagocytosed by intraglomerular mesangial cells and replenished by both the visceral layer of Bowman’s capsule (podocytes) and glomerular endothelial cells

Front 364

filtration slit

Back 364

space between adjacent pedicles, a filtration slit diaphragm links adjacent pedicels, the diaphragms consists of nephrin (a cell adhesion molecule) anchored by CD2AP (to actin filaments in the pedicel

Front 365

congenital nephritic syndrome

Back 365

caused by a mutation of the gene encoding nephrin, characterized by massive proteinurai and edema

Front 366

albuminuria

Back 366

presence of albumin in the urine, result of INC permeability of the glomerular endothelium, can be caused by vascular injury, hypertension, mercury poisoning and exposure to bacterial toxins

Front 367

glomerulonephrities

Back 367

occurs when the basal lamina becomes impaired, due to deposition of antigen-antibody complexes that are filtered from the glomeruli or from the reaction of antibasement membrane antibody with the basal lamina itself, there is an acute proliferative diffuse type and a rapidly progressive (crescentic) type

Front 368

lipoid nephrosis

Back 368

basal laminae are not congested with antibodies, but adjacent pedicels appear to fuse with one another, this disease is one of the most prevalent kidney disorders in children

Front 369

mesangiolysis

Back 369

occurs when antigen-immunoglobulin complexes are trapped in the mesangium, immunoglobulins interact with complement molecules and mesangial cells are damaged

Front 370

proximal convoluted tubule (PCT) (pars convoluta)

Back 370

composed of a simple cuboidal epithelium, is eosinophilic, evident striated border (microvili), 67-80% of Na+, CL-, H2O are resorbed, all glucose, amino acids, proteins is resorbed, also eliminates organic solutes, drugs, and toxins, lumen kept open by fluid pressure

Front 371

thin limbs of loops of Henle (pars recta)

Back 371

three regions (descending thin limb, Henle’s loop and the ascending thin limb), lined with squamous epithelium, often difficult to distinguish from capillaries, descending loop is permeable to H2O (presence of aquaporin channels) and reasonably permeable to urea, sodium, chloride and other ions, ascending loop is only slightly permeable to H2O

Front 372

distal convoluted tubule (DCT)

Back 372

has three regions: the pars recta (the ascending thick limb of Henle’s loop), the macula densa and the pars convulata (the distal convoluted tubule), sensitive to aldosterone levels (can resorb all Na+ and passively all Cl-), K+ and H+ are secreted into the lumen controlling K+ extracellular levels and acidity of urine, the ascending thick segment is simple cuboidal

Front 373

macula densa of DCT

Back 373

monitors filtrate for Na+ and Cl- as part of the JGA apparatus, are tall, narrow cells, region of the distal tubule where the ascending thick limb passes near its own renal corpuscle lying between the afferent and efferent glomerular arterioles

Front 374

thick ascending limb

Back 374

not permeable to water or urea, its cells have CL- pumps that function in the active transport of Cl- from the lumen of the tubule, perhaps also Na+ pumps,

Front 375

DCT

Back 375

short, lumina of these tubules are wide open, narrower cells, not as numerous mito, impermeable to water and urea, has high Na+, K+-ATPase activity that powers Na+-K+ exchange pumps, responds to aldosterone and can actively resorb almost all of the remaining Na+ from the lumen of the tubule into the renal interstitium, lysosomes not prominent (they are in PCT)

Front 376

components of JGA

Back 376

1. macula densa of the DCT
2. JG cells of afferent (and occasionally efferent) arteriole-modified smooth muscle cells of the tunic media, produce renin, angiotensin-converting enzyme (ACE), angiotensin I and II, JG cells communicate with the cells of the macula densa, round nuclei
3. extraglomerular mesangial cells-are connected to each other and to JG cells by gap junctions, angiotensin II causes contraction of these cells

Front 377

innervation of JG cells

Back 377

innervated by sympathetic nerve fibers, renin secretion is enhanced by norepinephrine and dopamine secreted by adrenergic nerve fibers

Front 378

key activites of collecting tubules

Back 378

1. to resorb H2O in response to ADH
2. to resorb sodium in response to aldosterone
3. to convey and modify the ultrfiltrate from the nephron to the minor calyces of the kidney

Front 379

structure of collecting tubules

Back 379

1. principal cells (H2O resorption in presence of ADH), absence of ADH, urine is copious and hypotonic, presence of ADH, urine volume is low and concentrated
2. two types of intercalated cells-acidifies urine, resorbing H+ and secreting HCO3-
3. has distinct lateral cell borders and lies mostly in medullary rays and medulla

Front 380

principle cells

Back 380

have oval, centrally located nuclei, infolding on basal membrane, posses numerous aquaporins that are very sensitive to antidiuretic hormone (ADH) and become completely permeable to water

Front 381

intercalated cells

Back 381

display numerous apical vesicles, two types (A and B), A have H+-ATPase on luminal surface acidifying urine and B have H+-ATPase on basolateral membrane functioning in resorbing H+ and secreting HCO3-

Front 382

regions of the collecting tubules

Back 382

cortical (located in the medullary rays and composed of principal and intercalated cells), medullary and papillary

Front 383

roles of renin in blood pressure regulation

Back 383

decrease in blood pressure causes: (1) a reduced stretch in afferent arterioles and (2) a reduced [Na+] and [Cl-] in filtrate

Front 384

reduced [Na+] and [Cl-] in filtrate

Back 384

acts on macula densa to release angiotensiogen (from the liver), this turns into angiotensin I, which turns into angiotensin II, which causes tonus to INC in arterioles which causes vascular space to DEC and acts on the zona glomerulosa of adrenal cortex to INC aldosterone, can also secrete ADH and thirst, angiotensin II can also be turned into angiotensin III which also acts on the zona glomerulosa of adrenal cortex to INC aldosterone, one have INC in aldosterone this causes an INC in renal rentetion of Na+ and H2O rasing blood volume and restoring blood pressure

Front 385

reduced stretch in afferent arteriole

Back 385

acts on JG cells to release renin which acts on angiotensinogen (from the liver) to form angiotensin I

Front 386

ACE (angiotensin-converting enzyme)

Back 386

converts angiotensin I to angiotensin II

Front 387

medullary collecting tubules

Back 387

larger, combination of several cortical collecting tubules, outer zone have both types of cells, but those on the inner zone have only principal cells

Front 388

papillary collecting tubules (ducts of Bellini)

Back 388

main collecting ducts, larger, combination of several medullary collecting ducts, lined by tall columnar principal cells only, open in the area cribosa of renal papilla

Front 389

minor calyxes

Back 389

beginning of transitional epithelium

Front 390

major calxyes

Back 390

accumulation of minor calyxes

Front 391

mucosa of the ureter

Back 391

stellate lumen lined by transitional epithelium, fibroelastic lamina propria, no mucosal or submucosal glands, no muscularis mucosae

Front 392

submucosa of the ureter

Back 392

absent

Front 393

muscularis externa of the ureter

Back 393

two layers in the upper two-thirds (ILOC), three layers in the lower 1/3, ILMCOL

Front 394

mucosa of the urinary bladder

Back 394

transitional epithelium, firbroelastic lamina propria

Front 395

muscularis externa of the urinary bladder

Back 395

IL MC OL

Front 396

adventitia of the urinary bladder

Back 396

fibroelastic adventitia is covered superiorly by peritoneum, forming a serosa

Front 397

mucosa of the female urethra

Back 397

transitional near the bladder, reaminder stratified squamous, non-keratinized, fibroelastic lamina propria, glands of Littre

Front 398

muscularis externa of the female urethra

Back 398

IL OC, at UG diaphragm picks up sphincter of skeletal muscle permitting voluntary control

Front 399

male urethra

Back 399

1. prostatic urethra-lined with transitional
2. membranous urethra-lined by stratified columnar
3. penile urethra-stratified columnar to stratified squamous non-keratizined (SSNK), glans of Littre, navicular fossa SSNK
4. vascular fibroelastic lamina propria in all sections

Front 400

chronic essential hypertension

Back 400

presence of elevated levels of angiotensin II caused by INC activity of ACE

Front 401

congenital nephrogenic diabetes insipidus

Back 401

X-linked disorder evidenced in male infants, leads to copious amounts of dilute urine due to the malformation of the V2 receptor

Front 402

gonadotropic hormones

Back 402

secreted by the pituitary gland and signal the initiation of puberty, leads to further differentiation of the reproductive organs

Front 403

menarche

Back 403

the first menstrual flow, about 9-15 years of age, average of 12.7

Front 404

ovaries

Back 404

covered by germinal epithelium (low cuboidal), divided into a cortex and medulla, suspended by the broad ligament of the uterus by an attachment called the mesovarium

Front 405

tunica albuginea

Back 405

beneath the germinal epithelium, is a dense, irregular collagenous CT capsule

Front 406

ovarian cortex

Back 406

composed of the CT stroma that houses ovarian follicles in various stages of development

Front 407

primordial germ cells (PGCs)

Back 407

in the female AKA oogonia, develop in the yolk sac endoderm, migrate to the germinal ridges to populate the ovarian cortex, about 1 million are covered with follicular cells and survive to birth, enter prophase of meisosi I and are known as primary oocytes, arrest at the diplotene stage

Front 408

secondary oocyte

Back 408

the oocyte that is formed after the primary oocyte completes its first meitotic division

Front 409

luteinizing hormone-releasing hormone (LHRH)

Back 409

AKA gonadotropin releasing hormone (GnRH), produced by the peroptic area of the hypothalamus, plays a major role in initiating puberty, released in a pulsatile nature for the onset of menarche, causes release of FSH and LH

Front 410

ovarian follicles

Back 410

evolve through four developmental stages: primordial, secondary and graafian,

Front 411

follicular cells

Back 411

surround the primary oocyte, arise from the mesothelial epithelium and possibly from the primary sex cords of the mesonephros (a precursor to the metanephros (the structure that develops into the kidney)), squamous, attached to each other via desmosomes

Front 412

primordial follicles

Back 412

composed of a single layer of flattened follicular cells that surround the primary oocyte, are separated from the ovarian stroma by a basement membrane

Front 413

primary follicles

Back 413

two types (unilaminar and multilaminar), depending on the number of layers of follicular cells that surround the primary oocyte, develop from primordial follicles, follicular cells become cuboidal shaped

Front 414

unilaminar primary follicle

Back 414

occurs as long as only a single layer of follicular cells encircles the oocyte

Front 415

multilaminar primary follicle

Back 415

occurs when the follicular cells begin to proliferate forming several layers of cells encircling the oocyte, follicular cells are now called granulose cells, zona pellucida appears (separates the oocyte from the follicular cells) as does a theca interna and externa

Front 416

zona pellucida

Back 416

composed of three different glycoproteins ZP1, ZP2 and ZP3

Front 417

theca interna

Back 417

organization of stromal cells around the multilaminar primary follicle, a richly vasculariezed cellular layer, possess LH receptors, produces androstenedione (male) which turns into estradiol

Front 418

theca externa

Back 418

composed mostly of fibrous CT

Front 419

activin

Back 419

signaling molecule that activates the proliferative activity of the granulose cells

Front 420

secondary (antral) follicles

Back 420

similar to primary follicles except for the presence of accumulations of liquor folliculi among the granulosa cells, comes from the multilaminar primary follicle, responsive to FSH (which stimulates an INC in the number of layers of granulose cells and liquor folliculi spaces)

Front 421

liquor folliculi

Back 421

fluid that fills intercellular spaces that develop within the mass of granulose cells, contains GAGs, proteoglycans, progesterone, estradiol, inhibin, folliostatin and activin which regulate the release of LH and FSH

Front 422

antrum

Back 422

coalescing of numerous liquor follliculi into a singl, fluid filled chamber

Front 423

cumulus oophorus

Back 423

granulose cells become rearranged so that the primary oocyte is now surrounded by a small group of granulosa cells that project out from the wall into the fluid filled antrum

Front 424

corona radiata

Back 424

single layer of granulosa cells that immediately surrounds the primary oocyte

Front 425

Graafian (mature) follicles

Back 425

may be as large as the entire ovary, it is these follicles that undergo ovulation, come from the maturation of the secondary follicles, has a membrana granulosa (follicular cells of the wall of the follicle)

Front 426

ovulation

Back 426

the process of releasing the secondary oocyte from the graafian follicle, by the 14th day, estrogen levels are high to cause a negative feedback inhibition that shuts off FSH release and a sudden surge of LH

Front 427

LH surge

Back 427

1. causes meiosis-inducing substance to be released causing the primary oocyte to complete its first meiotic division
2. the newly formed secondary oocyte arrests at metaphase of meiosis II
3. proteoglycans and hyaluronic acid by the granulosa cells attracts water causing an INC in the size of the graafian follicle
4. surface of the ovary loses its blood supply forming the stigma
5. stigma opens between the peritoneal cavity and the antrum of the graafian follicle
6. secondary oocyte is released resulting in ovulation, ovulation is always on the 14th day before the beginning of menstruation, have 24 hours to fertilize secondary oocyte
7. remnants of the graafian follicle are turned into the corpus luteum

Front 428

corpus luteum

Back 428

a temporary endocrine gland that manufactures and releases hormones that support the uterine endometrium, composed of granulosa-lutein cells and theca-lutein cells

Front 429

granulosa-lutein cells

Back 429

hormone producing cells that originated from the granulosa cells of the graafian follicle, 80% of the cell population of the corpus luteum, produces progesterone and convert androgens produced by the theca-lutein cells into estrogens, inhibit release of LH and FSH

Front 430

theca-lutein cells

Back 430

derived from the cells of the theca interna, secrete progesterone, androgens and estrogen, dark staining cells, inhibit release of LH and FSH

Front 431

degeneration of corpus luteum

Back 431

absence of LH (if pregnancy does not occur) leads to the degeneration of the corpus luteum,

Front 432

maintaing the corpus luteum

Back 432

if pregnancy occurs, human chorionic gonadotropin (hCG) is released and the corpus luteum is maintained, corpus luteum secretes hormones to maintain pregnancy

Front 433

corpus albicans

Back 433

formed as the corpus luteum degenerates, is phagocytosed by macrophages, fibroblasts enter, manufacture type I collagen and form this fibrous structure

Front 434

atretic follicles

Back 434

follciels that undergo degeneration, phagocytosed by macrophages, only a single gollicle ovulates during each menstrual cycle

Front 435

ovarian medulla

Back 435

is a richly vascularized fibroelastic connective tissue housing CT cells, interstitial cells (secrete estrogen) and hilar cells (secrete androgens)

Front 436

FSH

Back 436

stimulates the growth and development of secondary follicles, stimulates granulose cells to convert androges to estrogen, stimulates the synthesis of LH receptors on granulose cells, stimulates from secondary follicle on

Front 437

LH

Back 437

triggers primary oocyte to complete meiosis I and enter meiosis II, initiates ovulation, affects the transformation of remaining granulose and theca internal cells to leuteal cells

Front 438

estorgens

Back 438

maintains the female reproductive tract, responsible for the secondary sexual characteristics of the female, responsible for the rebuilding the uterus (proliferative phase) after menses, INC inhibits FSH [granulose cells secrete inhibin follistatin and activin which also regulate FSH secretion], induces a surge in LH levels

Front 439

progesterone

Back 439

initiates the conversion from a proliferative uterus to a secretory uterus for implantation, maintains the uterus in a secretory phase in pregrnancy, inhibits LH production

Front 440

inhibin

Back 440

inhibits FSH secretion

Front 441

human placental lactogen

Back 441

promotes mammary gland development during pregnancy, promotes lactogenesis

Front 442

relaxin

Back 442

facilitates parturition by softening the fibrocartilage of pubic symphysis, softens the cervix and facilitates its dilation in preparation for parturition

Front 443

oxytocin

Back 443

stimulates smooth muscle contraction of uterus during orgasm and during partition, stimulates contraction of myoepithelial cells of mammary gland assisting in milk ejection

Front 444

oviducts (fallopian tubes)

Back 444

act as a conduit for spermatozoa to reach the primary oocyte and to convey the fertilized egg to the uterus, paired muscular walled tubular structures, divided into four regions (infundibulum, ampulla (where fertilization usually takes place), isthmus, intramural region)

Front 445

oviduct covering

Back 445

covered by visceral peritoneum, walls composed of mucosa, muscularis and serosa,
1. mucosa-characterized by many longitudinal folds, present in all four regions, most prominent in the ampulla, lumen lined by simple columnar epithelium, constituted of nonciliated peg cells and ciliated peg cells, unremarkable lamina propria
2. muscularis-consists of poorly defined IC and OL layers of smooth muscle
3. serosa-simple squamous covering, loose CT between the serosa and muscularis provides many blood vessels and autonomic nerve fibers

Front 446

peg cells

Back 446

have no cilia, have a secretory function, providing a nutritive and protective environment for maintaining spermatozoa on their migration route to reach the secondary oocyte, facilitate capacitation of spermatozoa, also provide nutrion and protection to the ovum, prevent microorganisms in the uterus from moving to the oviduct, if ciliated beat towards the uterus to propel the fertilized ovum to the uterus

Front 447

uterus

Back 447

is a muscular organ consisting of a fundus, body and cervix,

Front 448

body and fundus of the uterus

Back 448

the uterine wall of the body and fundus is composed of an endometrium, myometrium, and either and adventitia or a serosa

Front 449

endometrium

Back 449

is the mucosal lining of the uterus, consists of two layers, the superficial functionalis and the deeper located basalis, composed of a simple columnar epithelium and a lamina propria, epithelial cells include ciliated secretory columnar cells and ciliated cells, lamina propria has tubular glands

Front 450

functionalis layer of the endometrium

Back 450

a thick superificial layer that is sloughed at menstruation, vascularized by helical arteries which originate from the arcuate arteries

Front 451

basalis layer of the endometrium

Back 451

a deep, narrow layer whose glands and CT elements proliferate and thereby regenerate the functionalis during each menstrual cycle, straight arteries supply the basalis, originate from the arcuate arteries

Front 452

myometrium

Back 452

composed of an IL, MC and OL layer of smooth muscle, thick muscular wall, middle layer is richly vascularized, houses the arcuate arteries and is called the stratum vasculare, at the cervix the myometrium is composed of fibrous CT, largest and most numerous during pregnancy when estrogen is highest (hypertrophy and hyperplasia occurs with the muscle)

Front 453

sersoa and adventitia of the uterus

Back 453

anterior portion covered by adventita (CT without an epithelial covering, retroperitoneal), fundus and posterior portion covered by serosa (CT with squamous mesothelium, intraperitoneal)

Front 454

endometriosis

Back 454

presence of endometrial tissue in the pelvis or in the peritoneal cavity, painful, may cause dymenorrhea and even infertility, 3 theories of how endometrial tissue outside the uterus occurred

Front 455

regurgitation theory

Back 455

proposes that menstrual flow escapes the uterus via fallopian tubes to enter the peritoneal cavity

Front 456

metaplastic theory

Back 456

suggests that the epithelial cells of the peritoneum differentiate into endometrial cells

Front 457

vascular (lymphatic) dissemination theory

Back 457

proposes that endometrial cells enter vascular channels during menstruation and are distributed by the blood vascular system

Front 458

cervix

Back 458

the terminal end of the uterus, extends into the vagina, lumen is lined by a mucus secreting simple columnar epithelium, external surface is covered by a stratified squamous nonkeratinized epithelium, wall of cervix consists mostly of dense, collagenous CT contaiing many elastic fibers and only a few smooth muscle fibers, cervical mucosa contains branched cervical glands

Front 459

cervical glands

Back 459

secrete a serous fluid that facilitates entry of the spermatozoa into the uterus , during pregnancy the secretions become more viscous, forming a plug of thickened mucus in the orifice of the cervix preventing entry of sperm and microorganisms into the uterus

Front 460

cervical carcinoma

Back 460

one of the most common cancers in women, INC in women with multiple sex partners and herpes infections, develops in the stratified squamous nonkeratinized epithelium

Front 461

menstrual cycle

Back 461

divided into the menstrual, proliferative (follicular), and secretory (luteal) phases

Front 462

menstrual phase (days 1-4)

Back 462

characterized by the desquamation of the functionalis layer of the endometrium, when bleeding from the uterus begins, coiled arteries are constricted and the endometrium is deprived of blood, leads to necrosis of the funtionalis, the basalis layer begins to proliferate and form cells that migrate to the surface

Front 463

proliferative (follicular) phase (days 4 to 14)

Back 463

characterized by a reepithelialization of the lining of the endometrium and renewal of the functionalis, reconstruction of the glands, CT and coiled arteries

Front 464

secretory (luteal) phase (days 15 to 28)

Back 464

characterized by thickening of the endometrium as a result of edema and accumulated glycogen secretions of the highly coiled endometrial glands

Front 465

ZP3 molecuels of the zona pellucida

Back 465

have two regions, sperm receptor that recognizes integral proteins of the pserm plasmalemma and the region that binds to receptor proteins located in the head of the sperm triggering acrosome reaction

Front 466

acrosin

Back 466

digests the zona pellucida permitting the flagellar movement of the spermatozoa to propel the sperm toward the oocyte

Front 467

previtelline space

Back 467

located between the zona pellucida and the oocyte cell membrane

Front 468

cortical reaction

Back 468

occurs when the sperm contacts the oocyte and prevents polyspermy, fast component involves a change in resting potential (lasts only a few minutes), slow component involves the release of the contents of numerous cortical granules into the perivitelline space, hydrolyze ZP3 receptors

Front 469

placenta previa

Back 469

occurs when the blastocyst implants in the lower portion of the uterus near the cervix, as the embryo grows it blocks the cervix preventing normal vaginal delivery, need to have a C section

Front 470

vagina

Back 470

a fibromuscular sheat, composed of three layers, the mucosa, muscularis and adventitia,

Front 471

mucosa of the vagina

Back 471

lumen of the vagina is lined by a thick stratified squamous nonkeratinized epithelium, store large amounts of glycogen (stimulated by estrogen), has a low pH due to formation of lactic acid, lamina propria is composed of loose fibroelastic CT containing a rich vascular supply, contains numerous lymphocytes

Front 472

muscularis layer of the vagina

Back 472

composed of smooth muscle cells arranged so that the mostly longitudinal bundles of the external surface intermingle with the more circularly arranged bundles near the lumen, sphincter muscle encircles the vagina at its external opening

Front 473

adventitia of the vagina

Back 473

dense, fibroelastic CT, has a rich vascular supply with a vast venous plexus and nerve bundles derived from the pelvic splanchnic nerves

Front 474

labia majora

Back 474

heavily endowed with adipose tissue and a thin layer of smooth muscle, has numerous sweat glands and sebaceous glands

Front 475

labia minora

Back 475

tow smaller folds of skin, devoid of hair follicles and adipose, core is spongy CT containing elastic fibers arranged in networks, numerous sebaceous glands and richly supplied with blood and nerve endings

Front 476

vestibule

Back 476

receives secretions of the glands of Bartholin and minor vestibular glands

Front 477

clitoris

Back 477

covered by stratified squamous epithelium and is composed of two erectile bodies containing numerous blood vessels and sensory nerves

Front 478

mammary glands

Back 478

are compound tubuloalveolar glands that consists of 15 to 20 lobes radiating out from the nipple and are separated from each other by adipose and collagenous CT

Front 479

formation of lobules and terminal ductules

Back 479

stimulated by estrogen, progesterone and prolactin, full development of the ductal protion requires glucocorticoids and somatotropin

Front 480

resting (nonsecreting) mammary glands

Back 480

alveoli are not developed in the resting mammary gland, alveoli only occur during pregnancy, lactiferous ducts are lined by a stratified squamous epithelium, lactiferous sinus and the lactiferous duct leading to it are lined by stratified cuboidal, have stellate myoepithelial cells located between the epithelium and basal lamina

Front 481

lactating (active) mammary glands

Back 481

during pregnancy, the terminal portions of the ducts branch and grow and develop secretory units known as alveoli, activated by elevated levels of estrogen and progesterone, alveoli are composed of cuboidal cells partially surrounded by a meshwork of myoepithelial cells, merocrine mode of exocytosis

Front 482

areola

Back 482

cotatins sweat glands, sebaceous glands and areolar glands of Montgomery

Front 483

nipple

Back 483

covered by stratified squamous epithelium, contain the terminal openings of the lactiferous ducts, wrinkling of skin of nipple results from the attachments of the elastic fibers, has abundant smooth muscle fibers circular around the nipple and radiating longitudinally along the long axis of the nipple

Front 484

mammary gland secretions

Back 484

prolactin (secreted when the placenta is detached) is responsible for the production of milk by the mammary glands, oxytocin is responsible for the milk ejection reflex

Front 485

breast carcinoma

Back 485

90% arises in ductal epithelium, second only to lung cancer as on eof the major causes of cancer related death in women, can be ductal carcinoma of the ductal cells and lobular carcinoma of the terminal ductules,

Front 486

testes

Back 486

paired organs that produce spermatozoa and testosterone, develops retroperitoneally on the posterior wall of the abdominal cavity, as they descend they carry with them a portion of the peritoneum (tunica vaginalis)

Front 487

tunica vaginalis

Back 487

forms a serous cavity that partially surrounds the anterolateral aspect of each testis, permitting it some degree of mobility within its compartment in the scrotum

Front 488

structure of the testes

Back 488

CT septa divide the testis into lobuli testis, each of which houses one to four seminiferous tubules

Front 489

tunica albuginea

Back 489

a capsule of dense, irregular collagenous CT that surrounds each testis

Front 490

tunica vasculosa

Back 490

deep to the tunica albuginea, highly vascularized loose CT

Front 491

mediastinum testis

Back 491

thickened posterior aspect of the tunica albuginea, CT tissue septa that divide the testes into lobuli testis

Front 492

seminiferous tubules

Back 492

1 to 4 of these in each lobule, blindly ending, surrouned by a richly innervated and highly vascularized loose CT derived from the tunica vasculosa, produce spermatozoa, enter short straight tubuli recti that connect to the rete testis, leave the rete testis through 10 to 20 short ductuli efferentes which fuse to form the epididymis

Front 493

vascular supply to each testis

Back 493

comes from the testicular artery, descend with the testis into the scrotum accompanying the vas deferens, forms many branches before it pierces the capsule of the testis to form the intratesticular vascular elements

Front 494

pampiniform plexus of veins

Back 494

the capillary beds of the testes drain into here

Front 495

spermatic cord

Back 495

consists of testicular artery, veins and vas deferens

Front 496

countercurrent heat exchange system for the testes

Back 496

blood in pampiniform plexus is cooler acting to reduce the temperature of the arterial blood, 95 degrees F

Front 497

hyperthermia

Back 497

has been identified as a factor in male infertility

Front 498

histology of seminiferous tubules

Back 498

composed of a thick seminiferous epithelium (composed of sertoli cells and spermatogenic cells) surrouned by a thin CT (tunica propria), are convoluted, hollow tubules, basal lamina present that seperates the tunica propria from the seminiferous epithelium, basal lamina composed of type I collagen housing several fibroblasts

Front 499

Sertoli cells

Back 499

support, protect and nourish spermatogenic cells, phagocytose cytoplasmic remnants of sermatids, secrete androgen-binding protein, hormones and a nutritive medium, and establish the blood-testis barrier, tall columnar cells, lateral and apical cell membrane have complex infoldings, with the apical in contact with the seminiferous tubules, cytoplasm has crystalloids of Charcot-Bottcher, has two compartments

Front 500

basal compartment of Sertoli cell

Back 500

narrower, located basal to the zonulae occludentes and surrounds the wider adluminal compartmentm, house spermatogonia

Front 501

adluminal compartment of Sertoli cell

Back 501

separated from CT influences by the zonulae occludentes, thereby protecting the gametes from the immune system, house primary spermatocytes -> spermatozoa

Front 502

functions of the Sertoli cells

Back 502

1. physical and nutritional support of the developing germ cell
2. phagocytosis of cytoplasm eliminated during spermiogenesis
3. establishment of a blood-testis barrier by the formation of zonulae occludentes between adjacent Sertoli cells
4. synthesis and release of androgen-binding proteins (facilitates an INC in [testosterone] the seminiferous tubules
5. synthesis and release of anti-mullerian hormone
6. synthesis and secretion of inhibin
7. secretion of a fructose rich medium that nourishes and facilitates the transport of spermatozoa
8. synthesis and secretion of testicular transferring (accepts iron from serum transferring and convetys it to maturing gametes)

Front 503

spmeratogenic cells

Back 503

responsible for spermatogenesis, compose most of the cells of the seminiferous epithelium, in various stages of maturation

Front 504

spermatogenesis

Back 504

divided into three phases: spermatocytogenesis (differentiation of spermatogonia into primary spermatocytes), meiosis (reduction division whereby diploid primary spermatocytes reduce their chromosome complement forming haploid spermatid), and spermiogenesis (transformation of spermatids into spermatozoa), go from spermatogonia through mitosis into primary spermatocytes through meiosis to secondary spermatocyte through another meiosis to form spermatids (haploid)

Front 505

Dark type A spermatogonia

Back 505

small, dome-shaped cells, flattened oval nuclei and heterochromatin, dense appearance, are reserve cells that have not entered the cell cycle, but may, undergo mitosis to form both dark and pale type A spermatogonia

Front 506

Pale type A spermatogonia

Back 506

identical to dark type A cells except that their nuclei have abundant euchromatin, induced by testosterone to proliferate and give rise to additional pale type A and type B

Front 507

Type B spermatogonia

Back 507

resemble pale type A but have round nuclei, give rise to primary spermatocytes

Front 508

primary spermatocytes

Back 508

migrate from the basal compartment to the adluminal compartment, form zonulae occludenetes with the Sertoli cells to help maintain the integrity of the blood-testis barrier, largest cells of the seminiferous epithelium, have 4n DNA content but chromosome number remains diploid (1st meiotic division splits only the DNA content, 2nd split both)

Front 509

stages of prophase I

Back 509

1. leptotene-condensation of chromosomes to thin threads
2. zygotene-pairing with homologue
3. pachytene-tetrad formation
4. diakinesis-crossing over

Front 510

spermiogenesis

Back 510

spermatids discard much of their cytoplasm, rearrange their organelles and form a flagellum to become transformed into spermatozoa, subdivided into four phases (golgi, cap, acrosomal and maturation)

Front 511

cytoplasmic bridge

Back 511

connect spermatids that are the progeny of a single pale type A spermatogonia

Front 512

golgi phase of spermiogenesis

Back 512

hydrolytic enzymes are formed on the RER, modified in the golgi and packaged in the trans Golgi as preacrosomal vesicles, becomes bound to the nuclear envelope establishing the anterior pole

Front 513

cap phase of spermiogenesis

Back 513

acrosomal vesicle INC in size, membrane surrounds the nucleus, becomes known as the acrosomal cap

Front 514

acrosomal phase of spermiogenesis

Back 514

characterized by several alterations in the morphology of the spermatid, nucleus becomes condensed, the cell elongates and the mito shift location, formation of manchette (microtubule structure which aids in elongation of the spermatid)

Front 515

maturation phase of spermiogenesis

Back 515

shedding of spermatid cytoplasm releasing individual spermatozoa, these are immotile and cannot fertilze an oocyte, gain motility when passing through the epididymis

Front 516

structure of spermatozoa

Back 516

composed of a head, housing the nucleus, and a tail that is divided into four regions (neck, middle piece, principal piece and end piece)

Front 517

head of spermatozoa

Back 517

surrounded by plasmalemma, occupied by condense electron-dense nucleus and the acrosome

Front 518

tail of the spermatozoon

Back 518

plasmalemma of the head is continuous with the tail’s plasma membrane

Front 519

neck of the spermatozoon

Back 519

connects the head to the remainder of the tail, composed of the nine columns of the connecting piece that encircles the two centrioles

Front 520

middle piece of the spermatozoon

Back 520

between neck and principal piece, presence of mito sheath which encircles the outer dense fibers and the centralmost axoneme, middle piece stops at the annulus

Front 521

principal piece of the spermatozoon

Back 521

longest segment of the tail, extends from the annulus to the end piece, axoneme continuous with that of the middle piece

Front 522

end piece of the spermatozoon

Back 522

composed of the central axoneme surrounded by plasmalemma, axoneme has 20 haphazardly arranged microtubules

Front 523

cycle of the seminiferous epithelium

Back 523

the seminiferous epithelium displays 16 day cycles, four cycles are required to complete spermatogenesis, so process of spermatogenesis requires 64 days

Front 524

interstitial cells of Leydig

Back 524

scattered among CT elements of the tunica vasculosa, secrete testosterone, have a single nucleus, but may be binucleate, have mito with tubular cristae, have crystals of Reinke in the cytoplasm

Front 525

histophysiology of the testes

Back 525

-LH can bind to LH receptors on the leydig cells and activate adenylyl cyclase and make cAMP, activate PKA, activate cholesterol esterases and cleave free cholesterol from lipids droplets, cholesterol desmolase converts free cholesterol to pregnenolone which turns into testosterone
-FSH induces Sertoli cells to synthesize and release ABP, binds testosterone and keeps it in the seminiferous tubule to sustain spermatogenesis
-cells that require testosterone have 5-alpha-reductase that turns testosterone into its active form dihydrotestosterone

Front 526

intratesticular ducts

Back 526

include the tubuli recti and the rete testis

Front 527

histology of the tubuli recti

Back 527

lined by Sertoli cells in the first half and by a simple cuboidal epithelium in their second half, have short stubby microvilla and most possess a single flagellum

Front 528

histology of the rete testis

Back 528

consists of labyrinthine spaces lined by a simple cuboidal epithelium, have numerous short microvilli with a single flagellum

Front 529

histology of the ductuli efferents

Back 529

simple epithelium that consists of patches of nonciliated cuboidal cells alternating with regions of ciliated columnar cells, sits on a basal lamina

Front 530

extracellular genital ducts

Back 530

are the epidiymis, ductus deferens and ejaculatory duct

Front 531

histology of the epididymis

Back 531

a highly convoluted tubule divided into a head (continuous with the ductuli efferentes), body (highly coiled body), and tail (stores spermatozoa for a short time), is continuous with the ductus deferens, lumen of the epididymis is lined with PSCC composed of two types of cells (basal and principal)

Front 532

basal cells of the epididymis

Back 532

pyramidial, round nuclei, large accumulation of heterochromatin, dense appearance, function as stem cells, regenerating themselves as well as the principal cells

Front 533

principal cells

Back 533

have irregular, oval nuclei with one or two large nucleoli, paler than basal cells, have many sterocilia, responsible for resorbing luminal fluid, phagocytose remnants of cytoplasm, also manufacture glycerophosphocholine

Front 534

histology of the vas deferens

Back 534

a muscular tube that conveys spermatozoa from the tail of the epididymis to the ejaculatory duct, has small, irregular lumen, has stereociliated PSCC, has a smooth muscle layer of IL, OL and MC

Front 535

ampulla of the vas

Back 535

dilated terminus of each vas, has a highly folded, thickened epithelium, it is joined by the seminal vesicle forming the ejaculatory duct

Front 536

ejaculatory duct

Back 536

enters the prostate at the colliculus seminalis, no smooth muscle

Front 537

accessory genital glands

Back 537

5, paired seminal vesicle, single prostate and paired bulbourethral glands

Front 538

seminal vesicles

Back 538

secrete a viscous fluid (frustose rich) that constitutes about 70% of the ejaculate, highly coiled tubular structures, mucosa is highly convoluted, lumen is lined with PSCC composed of short basal cells and low columnar cells (has short microvilli and a single flagellum), has subepithelial CT which is surrouned by smooth muscle cells (IC and OL)

Front 539

prostate gland

Back 539

secretes acid phosphatase, fibrinolysin and citric acid directly into the lumen of the urethra, has a slender capsule of richly vascularized, dense, irregular collagenous CT interspersed with smooth muscle cells, a conglomeration of 30 to 50 compound tubuloalveolar glands, arranged in three discrete, concentric layers (mucosal, submucosal and main), lined by simple to PSCC

Front 540

prostatic secretion

Back 540

constitutes a part of semen, a serous, white fluid rich in lipids, proteolytic enzymes, acid phosphataase, fibrinolysin and citric acid, regulated by dihydortestosterone

Front 541

adrenocarcinoma of the prostate

Back 541

2nd most common cancer in men, freq. the cancer cells enter the circulatory system and metastasize to bone, PSA (prostatic-specific antigen) used for early detection of prostatic adenocarcinoma

Front 542

bulbourethral (Cowper’s) glands

Back 542

located at the root of the penis, secrete a slippery lubricating solution directly into the urethra, has fibroelastic capsule with skeletal muscle fibers, epithelium is simple cuboidal to columnar, secretion is thick containing galactose and sialic acid that plays a role in lubricating the lumen of the urethra

Front 543

penis

Back 543

functions as an excretory organ for urine and as the male copulatory organ for the deposition of spermatozoa into the female reproductive tract, capsule (tunica albuginea) and three erectile bodies (corpora spongiosum and paired corpora cavernosa)

Front 544

erection

Back 544

occurs when blood flow is shifted to the vascular spaces of the erectile tissues (more so corpora cavernosum) causing the penis to enlarge and become turgid, parasympathetic impulses trigger release of NO which causes relaxation of smooth muscles of the branches of the deep and dorsal arteries INC blood flow into the organ, arteriovenous anastomoses are constricted diverting blood flow into the helical arteries

Front 545

sterile

Back 545

a male whose sperm count is less than 20 million spermatozoa per mL

Front 546

impotence

Back 546

inability to obtain erection

Front 547

Viagra

Back 547

blocked PDE from inhibiting cGMP degradation

Front 548

Exteroceptors

Back 548

stimulated by signals from the outside world like temperature, touch, pain and are part of the somatic afferent system that you are already know. Other signals from the outside world like light, sound and smell are also carried by exteroceptors but are considered to be special sensory and are the major topic of today’s lecture.

Front 549

Proprioceptors

Back 549

stimulated by signals that relate to body position in space like stretch and tension were covered in some detail in the muscle lectures.

Front 550

Interoceptors

Back 550

stimulated by signals arising in viscera like stretch and are part of the general visceral afferent system.

Front 551

three types of peripheral receptors

Back 551

mechanoreceptors, thermorecetpors, nociceptors

Front 552

Specialized Peripheral Receptors

Back 552

A. Merkel’s disks-touch
B. Meissner’s corpuscles-tactile discrimination
C. Pacinian corpuscles-pressure, vibration
D. Naked nerve endings-Nociceptors and thermoreceptors
G. Muscle spindle-length changes and rate of change in length
E. Golgi tendon organs-tension

Front 553

special sense

Back 553

three layers form the globe:
1. outer layer/fibrous: sclera (opaque) and cornea (translucent)
2. middle layer/vascular layer: chorioid, ciliary body, iris
3. inner layer: retina/neural

Front 554

sclera

Back 554

is comprised of collagen and elastic fibers giving it strength for the attachment of the extraocular eye muscles to move the eye

Front 555

cornea

Back 555

is avascular and highly innervated and is comprised of five distinct layers but basically consists of an outer stratified squamous epithelium (rapid turnover for healing), a middle (thickest part) stroma of collagen fibers (contains the canal of Schlemm), and an inner simple squamous epithelium acitve in maintaining fluid levels in the stroma

Front 556

canal of Schlemm

Back 556

moves fluid from the anterior chamber to the venous system and blockages of this flow can cause glaucoma

Front 557

flow of aqueous humor

Back 557

from ciliary process to scleral venous sinus (Schlemm’s canal)

Front 558

iris

Back 558

pigmented layer, sphincter of pupil, dilator of pupil, a pigmented layer that forms the pupil and houses the dilator and constrictor pupillae muscles

Front 559

glaucoma

Back 559

increased intraocular pressure (greater than 20-22 mm) caused by failure of drainage of the aqueous humor from the anterior chamber of the eye, treatment is to reopen the canal or DEC the production of aqueous humor

Front 560

ciliary body

Back 560

is an epithelium lined body of connective tissue and smooth muscle. It is responsible for changing the shape of the lens and secreting aqueous humor from the ciliary process.

Front 561

choroid

Back 561

a loose connective tissue layer with abundant capillaries and lots of melanocytes which account for the other name of this layer, the pigmented layer. The choroid is responsible for supplying nutrients to the retina.

Front 562

ciliary process

Back 562

secretes aqueous fluid, smooth muscle involved in changing the shape of the lens, lens is attached to the ciliary body by zonule fibers

Front 563

retina

Back 563

is the neural layer and is comprised of 10 layers

Front 564

most external layer (pigmented layer)

Back 564

is the RPE-retinal pigmented epithelium, the layer responsible for recycling the shed discs of the rods, providing metabolic support for the photoreceptors and absorbing light that has passed through the other layers of the retina, this is also the layer that can be separated from the rest of the retina in a detached retina, cause of partial blindness, can be corrected surgically by spot welding the two structures back together, if left unattended rods and cones can die, leaves a blind spot in the visual field corresponding to the area where the photoreceptors were lost

Front 565

photoreceptor layer

Back 565

next layer in from the pigmented layer, is the photoreceptor layer containing the rods and cones. Rods are for dim light, have high sensitivity but poor acuity and are distributed in diminishing number from the parafoveal zone out to the periphery of the retina. Cones are for bright light, color vision are less sensitive but have high acuity and are concentrated in the foveal region.

Front 566

photoreceptor distribution in the retina

Back 566

number of rods diminishes as you move away from the parafoveal region (has lots of rods) out to the anterior part of the retina, fovea centralis has lots of cones (where visual acuity is best)

Front 567

rods and cones

Back 567

When rods are stimulated by light they become hyperpolarized and inhibit neurotransmitter release into bipolar cells. This is different from the process seen in most other excitable cells. They do not fire action potentials, but instead have graded responses that are transmitted on to the bipolar and ultimately to ganglion cells. Cones work in a similar fashion but are of three different types based on different varieties of photopigment, each being maximally sensitive to either red, green or blue light.

Front 568

photoreceptor communication with biopolar cells

Back 568

The photoreceptors communicate with bipolar cells in the inner nuclear layer and numerous other cell layers can modify the signal before it reaches the ganglion cells in the innermost layer. Axons of ganglion cells pass across the inner layer of the retina and ultimately leave through the optic disc in the optic nerve (hence the blind spot). Keep in mind that light has to pass through all of the cell layers before it reaches the photoreceptors. Not necessarily the most efficient system, but we live in a bright light environment.

Front 569

optic nerve

Back 569

Ganglion cell axons forming the optic nerve must pass from there originating cell body to the optic disc. In doing so they circumvent the area of highest visual acuity (fovea)

Front 570

eyeball

Back 570

1. anterior and posterior chambers-separated from each other by the iris
2. lens-(suspended by zonular fibers) Has a capsule of collagen and glycoprotein, a subcapsular epithelium of cuboidal cells which give rise to the bulk of the lens made of lens fibers. Lens fibers are long cells which lose their organelles and continue to elongate throughout life. Cataracts are age related increases in opacity of the lens.
3. vitreous body-(colorless, transparent gel, 99% water) with hyaloid canal

Front 571

presbyopia

Back 571

the inability of the eye to focus on near objects (accommodation) and is caused by an age-related DEC in the elasticity of the lens, lens cannot become spherical for exact focusing, correct with corrective lenses

Front 572

cataract

Back 572

lens become opaque impairing vision, may be due to an accumulation of pigment, do not respond to medication and eventually lead to blindness, lens may be excised and replaced with a corrective lens

Front 573

eye floaters (vitreous opacities)

Back 573

speck, clouds or cobwebs persons appear to see in front of their eyes represent small debris that is floating in the vitreous body, caused by dehydration, cast shadows on the retina, can use specialized laser treatments

Front 574

conjunctivitis

Back 574

an inflammation of the conjunctiva usually associated with hyperemia and a discharge, may be caused by bacteria, virus, allergens and parasites, some are contagious, damage the eye and may cause blindness

Front 575

ear

Back 575

Can be divided into an outer, from the auricle to the tympanic membrane, a middle, from the tympanic membrane to the oval and round windows, and an inner ear housed in the temporal bone consisting of the cochlea for hearing and the semicircular canals and utricle and saccule for balance.

Front 576

external ear

Back 576

auricle & external auditory meatus. Captures, funnels sound, has modified sweat glands, ceruminous glands which produce cerumen (earwax) to keep big bugs out.

Front 577

middle ear

Back 577

air-filled cavity behind the ear drum. 3 bones transfer ear drum vibrations to oval window and fluid behind oval window, is lined with simple squamous for most of the lining but pseudostratified ciliated columnar as it approaches the auditory tube, Amplifies the sound signal, it makes up for the energy which is lost as sound moves from air into a liquid medium

Front 578

inner ear

Back 578

Fluid filled cochlea and vestibular apparatus. Holds sensory hair cells for hearing and balance, Cochlea- apparatus of hearing Semicircular canals, utricle and saccule- apparatus of balance, Bony part, membranous part and sensory part

Front 579

auditory tube

Back 579

air filled space in the temporal bone, communicates posteriorly with the mastoid cells and anteriorly with the pharynx

Front 580

otitis media

Back 580

Infection of the middle ear is very common. Microorganisms enter the middle ear via the auditory tube. It is especially common in children whose auditory tube is angled slightly superiorly towards the nasal cavity, The middle ear fills with fluid, The tympanic membrane gets red and inflamed

Front 581

utricle

Back 581

contains a dilated area with neuroepithelial cells called hair cells, type I and II, surrounded by supporting cells. All the hair cells have one kinocilium and many stereo cilia. When the stereo cilia are deflected towards the kinocilium the cell fires an action potential along a fiber of the 8th nerve. Otoliths are calcium carbonate granules embedded in a membrane above the cells.

Front 582

otoliths

Back 582

move in response to acceleration forces and cause bending of the stereocilia, to ultimately tell our nervous system which way we are moving. The utricle senses vertical acceleration and the saccule senses horizontal acceleration

Front 583

semicircular canals

Back 583

function in a similar manner but sense rotational movements instead of linear movements

Front 584

organ of corti

Back 584

continues around all the loops of the cochlear apparatus, a slice through one coil yields the following picture

Front 585

cochlea detail

Back 585

As the basilar membrane deflects up and down the hairs on the hair cells will bend back and forth because of the shear of the tectorial membrane. Bending the hairs of the inner hair cells causes depolarization in the afferent fibers of the 8th nerve. The outer hair cells receive efferent fibers and most researchers believe they can control the length of their cilia and alter the amount of deflection of the tectorial membrane. This could result in a tuning property on the basilar membrane and ultimately affect the firing of the inner hair cells

Front 586

Menier’s disease

Back 586

a disorder characterized by hearing loss resulting from excess fluid accumulation in the endolymphatic duct, may include vertigo, tinnitus, nausea, in severe cases the vestibular division nerve may have to be severed and the semicircular canals and cochlea may have to be removed

Front 587

conductive deafness

Back 587

any condition that impedes the conduction of the sound waves from the external ear through the middle ear and into the organ of Corti

Front 588

nerve deafness

Back 588

results from a disease process that interrupts transmission of the nerve impulse, may be located anywhere in the cochlear division of the acoustic nerve, may be caused by rubella, tumors of the nerve and nerve degeneration