Physiology Exam 4

Front 1

Molecules are thought to be transported across membranes of intestinal mucosal cells, or through tight junctions between mucosal cells, by all of the following processes EXCEPT:
a. Simple diffusion
b. Facilitated diffusion
c. Active transport
d. Solvent drag
e. Railway

Back 1

e. Railway

Front 2

Which of the following factors enhances fat solubility of a compound?
a. The compound, when placed in the watery medium of the gastrointestinal tract, carries a charge.
b. The compound is a strong electrolyte.
c. The high acidity of the stomach lumen for weak bases, like morphine.
d. The high acidity of the stomach lumen for weak acids, like aspirin
e. Dietary protein binding.

Back 2

d. The high acidity of the stomach lumen for weak acids, like aspirin

Front 3

What percentage of the cardiac output normally flows through the GI circulation?
a. 10%
b. 30%
c. 50%
d. 70%
e. 90%

Back 3

b. 30%

Front 4

Exercise, like a long-distance run, is associated with sustained sympathetic discharge, shunting of blood away from the GI tract, a decline in blood flow to the digestive tract, and an increase in vascular resistance. However, blood flow eventually returns toward normal during the run for all of the following reasons, EXCEPT:
a. Precapillary smooth muscle becomes refractory to constriction (i.e., escape), thus restoring intestinal blood flow.
b. Decreased blood flow creates local hypoxia, which itself causes relaxation of vascular smooth muscle, thereby restoring intestinal blood flow.
c. beta-adrenergic receptors predominate on vascular smooth muscles of the digestive tract.
d. Sympathetic stimulation relaxes the walls of hollow organs (i.e. the digestive tract), which decreases resistance to blood flow.
e. Sympathetic stimulation increases systemic arterial pressure, increases venous return and cardiac output, thereby helping to restore blood flow to the digestive tract.

Back 4

c. beta-adrenergic receptors predominate on vascular smooth muscles of the digestive tract.

Front 5

An increase in parasympathetic activity to the digestive tract results in an increase in mesenteric blood flow because:
a. It enhances visceral smooth muscle contraction as well as secretory activity, thus increasing the presence of vasodilator metabolites.
b. Levels of acetylcholine increase in circulating plasma, thus indirectly enhancing blood flow.
c. GI hormones are released locally, which in turn regulate mesenteric blood flow.
d. Parasympathetic fibers innervate arteriolar smooth muscle of the GI tract, and, when stimulated, increase mesenteric blood flow.
e. Parasympathetic-mediated vasoconstriction of peripheral blood vessels causes a shift in blood flow away from the periphery, toward the digestive tract.

Back 5

a. It enhances visceral smooth muscle contraction as well as secretory activity, thus increasing the presence of vasodilator metabolites.

Front 6

Hypoxic conditions at the intestinal villus tip:
a. Would adversely affect disaccharide and dipeptide digestion.
b. Are independent of villus structure.
c. Lead to normal desquamation of mucosal cells.
d. Are relatively unimportant, since this portion of the villus has comparatively low metabolic activity.
e. Indicates intestinal ischemia.

Back 6

c. Lead to normal desquamation of mucosal cells.

Front 7

The interstitial fluid osmolarity at the tip of an absorbing intestinal villus:
a. Is normally low (about 250 mOsm), due to the extensive amount of water absorbed.
b. Is established by water movement across the two arms of its hairpin vascular loop, and maintained by the active absorption of Na+.
c. Could be as fine as that found in the papilla of the kidney (i.e., 1200 mOsm).
d. Is established and maintained by the active absorption of Na+.
e. Is established and maintained by the water movement across the two arms of its hairpin vascular loop.

Back 7

c. Could be as fine as that found in the papilla of the kidney (i.e., 1200 mOsm).

Front 8

Select the TRUE statement below regarding oral fluid absorption:
a. A 400 mOsmolar solution of mannitol would be readily absorbed from the intestinal tract.
b. If a hypertonic solution is administered orally, diarrhea usually ensues.
c. Absorption of oral fluids occurs largely across mucosal cells of the digestive tract.
d. As long as oral fluids are of lower tonicity than the fluid in the most hypertonic part of the lateral intercellular spaces of the digestive tract, luminal fluid is absorbed along its osmotic gradient.
e. Oral fluids must be hypotonic (i.e. less than 290 mOsmolar) in order to be properly absorbed across the digestive tract.

Back 8

d. As long as oral fluids are of lower tonicity than the fluid in the most hypertonic part of the lateral intercellular spaces of the digestive tract, luminal fluid is absorbed along its osmotic gradient.

Front 9

Select the TRUE statement below regarding mechanical processes of the digestive tract:
a. The basic electrical rhythm is more rapid in proximal (e.g. duodenum), than in distal gut segments.
b. Visceral smooth muscle of the gut resists slow stretch, and responds with little or no tension increase when stretched quickly.
c. The gut's submucosal, or Meissner's plexus, carries out sensory reflexes, but is incapable of executing neural functions without extrinsic innervation.
d. The gut's myenteric, or Auerbach's plexus, has autonomic innervation, but does not noticeably affect tonus of the gut wall.
e. Intramural plexuses of the digestive tract exist in the intestine, but not in the stomach and esophagus.

Back 9

a. The basic electrical rhythm is more rapid in proximal (e.g. duodenum), than in distal gut segments.

Front 10

Sympathetic fibers to the digestive tract:
a. When activated cause sphincters to relax.
b. When activated have little effect on vascular smooth muscle contraction.
c. Generally stimulate visceral smooth muscle contraction.
d. When cut, have little adverse effect on alimentary tract motility.
e. When activated lead to an increase in intestinal mucus secretion.

Back 10

d. When cut, have little adverse effect on alimentary tract motility.

Front 11

Vagal denervation produces markedly acute effect on:
a. Ileal motility.
b. Jejunal digestive and absorptive processes.
c. Esophageal peristalsis and anorectal activity.
d. Colonic motility.
e. Duodenal motility and absorptive processes.

Back 11

c. Esophageal peristalsis and anorectal activity.

Front 12

Which one of the following statements regarding swallowing is FALSE?
a. The swallowing center in the medulla is involved in normal deglutition.
b. The oral phase of swallowing is associated with reflex inhibition of respiration.
c. Neuromuscular disorders (e.g. Myasthenia gravis), may cause pharyngeal paralysis leading to dysphagia and megaesophagus.
d. During swallowing, the soft palate is pulled upward, and the palatopharyngeal folds move inward toward one another, thus normally preventing reflux of food into the nasopharynx.
e. The vocal cords are normally pulled together during swallowing.

Back 12

b. The oral phase of swallowing is associated with reflex inhibition of respiration.

Front 13

Secondary esophageal peristalsis:
a. Occurs only with an associated pharyngeal component.
b. Occurs only following a primary peristaltic wave.
c. Helps to clear the esophagus of food residue and material refluxed from the stomach.
d. Is voluntary, and normally lasts about 1 second.
e. Occurs only following vagal activation.

Back 13

c. Helps to clear the esophagus of food residue and material refluxed from the stomach.

Front 14

Which one of the following agents causes increased tension in the LES?
a. Cholecystokinin
b. Vasoactive Intestinal Polypeptide
c. Progesterone
d. Gastric inhibitory Polypeptide
e. Gastrin

Back 14

e. Gastrin

Front 15

The migrating motor complex of the small bowel:
a. Normally cycles every 10 to 15 minutes.
b. Is also known as the interdigestive housekeeper.
c. Is primarily associated with antiperistaltic contraction.
d. Is best characterized as the digestive, fed pattern of intestinal motor activity.
e. Remains unassociated with pancreatic or biliary secretion.

Back 15

b. Is also known as the interdigestive housekeeper.

Front 16

All of the following statements are TRUE regarding mixing and/or emptying of gastric contents, EXCEPT:
a. Dietary fats delay gastric emptying.
b. Major mixing activity occurs in the antrum, with simultaneous contraction of the pylorus and antrum being known as systolic contraction.
c. The frequency of gastric contractions following a meal is typically about 3 per minute.
d. The rate of gastric emptying is normally regulated by mechanisms that feedback negatively from the duodenum, thus diminishing the force of antral contractions.
e. Solid contents of the stomach are generally emptied more rapidly into the duodenum than liquid contents.

Back 16

e. Solid contents of the stomach are generally emptied more rapidly into the duodenum than liquid contents.

Front 17

The rate of gastric emptying is slowed by all of the following factors, EXCEPT:
a. Presence of starch and other carbohydrates in the duodenum.
b. Hypertonic solutions in the duodenum.
c. Presence of fatty acids or monoglycerides in the duodenum.
d. Duodenal contents with a pH of less than 3.5.
e. Presence of amino acids (particularly tryptophan) and peptides in the duodenum.

Back 17

a. Presence of starch and other carbohydrates in the duodenum.

Front 18

Which one of the following reflexes is/are best association with increased gastrin secretion?
a. Intestinointestinal
b. Ileogastric
c. Gastroileal, gastrocolic, and vasovagal
d. Oculorectal
e. Colonic

Back 18

c. Gastroileal, gastrocolic, and vasovagal

Front 19

Select the FALSE statement below regarding large bowel motility:
a. The gastrocolic reflex may be weak or absent in patients with IBS.
b. Most contractions of the cecum and proximal part of the large bowel are segmental.
c. In the proximal colon, antipropulsive patterns are not uncommon.
d. Haustral contractions normally occur with regularity in the colon.
e. Most colonic contractions serve to mix and circulate chyme in order to facilitate water and electrolyte absorption across mucosal epithelium.

Back 19

a. The gastrocolic reflex may be weak or absent in patients with IBS.

Front 20

Select the TRUE statement below regarding defecation:
a. The rectum is usually full of fecal matter.
b. The canine rectum must be filled with at least 1 liter of fecal matter before the defecation urge is experienced.
c. During defecation, intra-abdominal pressure is increased by contraction of abdominal muscles, but usually not te diaphragm.
d. Difficulties in defecation occur when fecal residue is reduced.
e. During defecation, the internal anal sphincter is usually contracted while the external anal sphincter is relaxed.

Back 20

d. Difficulties in defecation occur when fecal residue is reduced.

Front 21

Select the FALSE statement below regarding digestive enzymes.
a. Symbiotic digestive enzymes are part of the metabolic scheme of microbes, and are found in the gut of all domestic animal species.
b. Constitutive enzymes catalyze hydrolysis of protein and lipid, but not carbohydrates.
c. Microorganisms entering the small bowel from the abomasum can be digested by constitutive enzymes, thus providing excellent nutrients for the host.
d. The lack of necessary molecular oxygen in the rumen forces microbes to use carbohydrate (i.e., cellulose), both as an energy source and an oxygen source.
e. Food energy and carbon released from gut microbes following symbiotic digestion of ingesta is largely in the form of volatile fatty acids.

Back 21

b. Constitutive enzymes catalyze hydrolysis of protein and lipid, but not carbohydrates.

Front 22

The predominant short-chain VFA produced by the normal rumen microbial population is:
a. acetate, a ketogenic VFA
b. Propionate, a glucogenic VFA
c. Butyrate, a ketogenic VFA
d. Lactate, a glucogenic VFA
e. Succinate, a ketogenic VFA

Back 22

a. acetate, a ketogenic VFA

Front 23

Hepatic conversion of propionate to succinyl-CoA requires all of the following, except:
a. Mg++
b. Biotin
c. Acetyl-CoA
d. Vitamin B12 (and thus cobalt)
e. Adenosine triphosphate

Back 23

c. Acetyl-CoA

Front 24

Select the FALSE statement below regarding nitrogen metabolism in the ruminant digestive tract.
a. Much of dietary protein is hydrolyzed by rumen microbes.
b. Salivary urea is normally hydrolyzed to ammonia and CO2 by potent microbial urease activity in the rumen.
c. Microbial protein serves as an important dietary source of amino acid for the host.
d. Increased levels of rumen NH3 lower rumen pH, thus predisposing animals to metabolic acidosis.
e. Increased dietary (soluble) carbohydrate tends to reduce the rumen NH3 concentration.

Back 24

d. Increased levels of rumen NH3 lower rumen pH, thus predisposing animals to metabolic acidosis.

Front 25

Select the TRUE statement below regarding VFA and/or glucose disposition in the ruminant organism.
a. VFAs cannot be converted to ketone bodies by rumen epithelial cells.
b. Under normal circumstances, approximately 85% to 95% of VFA in the systemic circulation of the ruminant is acetate.
c. The vast majority of VFAs are normally absorbed from the reticulum and omasum.
d. Rumen epithelial cells preferentially utilize plasma glucose as their primary source of energy.
e. Beta-hydroxybutyrate is the VFA most highly utilized by adipose tissue for triglyceride formation.

Back 25

b. Under normal circumstances, approximately 85% to 95% of VFA in the systemic circulation of the ruminant is acetate.

Front 26

Select the FALSE statement below regarding rumen pH.
a. As rumen pH decreases (to a limited extent), VFA absorption is favored.
b. A lower rumen pH increases microbial production of propionate and butyrate relative to acetate.
c. Concentrated rations tend to decrease rumen pH.
d. VFAs are absorbed more readily from the rumen when in the ionized, free acid form.
e. Since the pKa of the VFAs is about 4.8, which is well below normal rumen pH, most exist in rumen contents in the dissociated, ionic form.

Back 26

d. VFAs are absorbed more readily from the rumen when in the ionized, free acid form.

Front 27

Select the TRUE statement below regarding metabolism in ruminant fat tissue.
a. Lipolysis results in the generation of glucose (from glycerol) in ruminant adipocytes, and therefore glucose as well as FFAs are added to the circulation.
b. Glycerokinase, which is found in high concentration in ruminant adipose tissue, catalyzes conversion of glycerol to glycerol-3-phosphate, which can then be used in triglyceride synthesis.
c. Lipogenesis in the ruminant adipocyte occurs primarily from circulating acetate for fatty acid biosynthesis, and glucose for glycerol biosynthesis.
d. Glucose enters the circulation from ruminant adipocytes dur primarily to the action of glucose-6-phosphatase.
e. Glycerol is normally used to form fatty acids in ruminant adipocytes.

Back 27

c. Lipogenesis in the ruminant adipocyte occurs primarily from circulating acetate for fatty acid biosynthesis, and glucose for glycerol biosynthesis.

Front 28

Select the FALSE statement below regarding ruminant hepatocytes. They:
a. Normally export bile acids and bilirubin into bile, but not cholesterol.
b. Are normally in a continual state of gluconeogenesis, attempting to maintain the plasma glucose concentration.
c. Are known to export proteins (including albumin, clotting factors, and lipoproteins) to the circulation.
d. Are a primary source of urea, and therefore nitrogen for rumen microbial protein synthesis.
e. Produce ketone bodies for use by muscle, mammary, and nerve tissue.

Back 28

a. Normally export bile acids and bilirubin into bile, but not cholesterol.

Front 29

Dietary triglycerides and phospholipids in ruminant animals:
a. Normally escape symbiotic digestion, but are digested in the small bowel by constitutive enzymes from the pancreas.
b. Can usually be recovered from the rumen as mono and/or diglycerides.
c. Are hydrolyzed by rumen microbes that also typically unsaturate the saturated fatty acids.
d. Are hydrolyzed by rumen microbes that typically metabolize the glycerol to propionate.
e. Are normally found in high concentrations in hepatic portal blood.

Back 29

d. Are hydrolyzed by rumen microbes that typically metabolize the glycerol to propionate.

Front 30

Select the FALSE statement below regarding reticulorumen motility:
a. Reticulorumen motility patterns are classified as being those associated with either mixing or eructation contractions.
b. Coarse, fibrous feeds tend to reduce both the force and frequency of reticulorumen contractions.
c. In general, reticulorumen contractions occur with a frequency of about 1 to 3 per minute during feeding, and normally disappear during deep sleep.
d. The major function of secondary reticulorumen contractions is to move CO2 and CH4 toward the cardia.
e. Primary contractions normally begin with a double, or biphasic contraction of the reticulum.

Back 30

b. Coarse, fibrous feeds tend to reduce both the force and frequency of reticulorumen contractions.

Front 31

The dorsal vagal nucleus of the brainstem receives afferent signals from the reticulorumen that helps coordinate reticulorumen motility patterns. These signals occur in response to all of the following luminal stimulie EXCEPT:
a. Degree of distention
b. Ingesta consistency
c. pH
d. Temperature
e. VFA concentration and ionic strength

Back 31

d. Temperature

Front 32

Which one of the following actions best describes the omasum?
a. Mix
b. Store
c. Absorb
d. Secrete
e. Pump

Back 32

e. Pump

Front 33

The camelid's digestive tract supports pregastric fermentation, and is therefore similar to that of true ruminants. However, there are some basic anatomical and physiologic differences. Which one of the following is FALSE regarding basic differences between the two?
a. A functional structure similar to the omasal pump seems absent in camelids.
b. All compartments of the camelid forestomach are glandular, whereas those in true ruminants are not.
c. Llamas are known to develop ulcers in the distal part of C3 (analogous to the abomasum of true ruminants), whereas true ruminants rarely develop abomasal ulcers.
d. The esophageal groove of true ruminants is single lipped, whereas that of camelids is double lipped.
e. The abomasum of true ruminant animals is entirely covered with enzyme and acid-secreting cells, where only the distal one-fifth of the analagous gut segment in camelids contains enzyme and acid-secreting cells.

Back 33

d. The esophageal groove of true ruminants is single lipped, whereas that of camelids is double lipped.

Front 34

The largest endocrine organ of the body is the:
a. Liver
b. Pancreas
c. Brain
d. GI tract
e. Adrenal Gland

Back 34

d. GI tract

Front 35

Hormones of the digestive tract regulate all of the following GI functions EXCEPT:
a. Absorption
b. Motility
c. Secretion
d. Blood flow
e. Digestion

Back 35

a. Absorption

Front 36

Which one of the following is NOT a general characteristic of GI chemical messengers?
a. Neurotransmitter
b. Nutrient
c. Neuroendocrine agent
d. Hormone
e. Paracrine agent

Back 36

b. Nutrient

Front 37

Select the FALSE statement below regarding amine precursor uptake and decarboxylation (APUD) cells:
a. APUD cells are normally found in the placenta
b. Neuroendocrine tumors of the gut (APUDomas) may sometimes secrete more than one peptide.
c. APUD cells are normally found in the hypothalamus, pituitary axis, and pineal gland.
d. APUDomas that secrete peptides foreign to their cell of origin cause orthoendocrine syndromes.
e. APUD cells are normally found in the digestive tract, pancreas, thyroid, and parathyroid glands.

Back 37

d. APUDomas that secrete peptides foreign to their cell of origin cause orthoendocrine syndromes.

Front 38

Gastrin shares biologic activity and a common 5 amino acid sequence with:
a. Secretin
b. Glucagon
c. CCK
d. Somatostatin
e. GIP

Back 38

c. CCK

Front 39

Which of the following is considered to be a weak stimulator of gastrin release into blood from G-cells of the stomach antrum?
a. Carboydrates, fats, and native proteins in the stomach lumen.
b. Vagal activation
c. Solutions of Ca++ salts in the stomach lumen.
d. Stomach distension
e. Peptides and L-amino acids in the stomach lumen.

Back 39

a. Carboydrates, fats, and native proteins in the stomach lumen.

Front 40

Two neurotransmitters that are thought to regulate gastrin release are:
a. Norepinephrine and acetylcholine
b. Acetylcholine and bombesin
c. Serotonin and norepinephrine
d. Somatostatin and cholecystokinin
e. Secretin and dopamine

Back 40

b. Acetylcholine and bombesin

Front 41

Which one of the following is NOT a normal physiologic action of gastrin?
a. Decrease lower esophageal sphincter pressure.
b. Trophic effect on the gut.
c. Increase gastric motility.
d. Increase gastric pepsinogen release.
e. Decrease ileocecal sphincter pressure.

Back 41

a. Decrease lower esophageal sphincter pressure.

Front 42

Functions of histamine in the GI tract include all of the following EXCEPT:
a. Increase gastric HCl secretion.
b. Vasodilate arterioles of the stomach and other areas of the gut.
c. Suppress pepsinogen secretion.
d. Decrease LES pressure.
e. Increase gut motility.

Back 42

c. Suppress pepsinogen secretion.

Front 43

CCK:
a. Decreases exocrine pancreatic enzyme secretion.
b. Inhibits gallbladder contraction.
c. Stimulates gastric emptying.
d. Decreases pancreatic and biliary ductular HCO3- secretion.
e. Is capable of both relaxing and contracting the LES.

Back 43

e. Is capable of both relaxing and contracting the LES.

Front 44

CCK:
a. Is present in K cells of the duodenal and jejunal mucosa, as well as the ileum.
b. Is normally released into blood in response to lipids and protein digestion products in the duodenum.
c. Stimulates enkephalin receptors like naloxone.
d. Stimulates the hunger center of the brain.
e. Was discovered by Harper and Raper in the early 1940s.

Back 44

b. Is normally released into blood in response to lipids and protein digestion products in the duodenum.

Front 45

Select the FALSE statement below regarding secretin:
a. Secretin was the first hormone discovered, and therefore has played a role in initiating the science of endocrinology.
b. Secretin opposes the action of CCK on the pancreas.
c. Secretin release is inhibited above a luminal duodenal pH of 4.5.
d. Secretin opposes the trophic action of gastrin on the GI mucosa.
e. Secretin shows structural (and therefore biologic) similarity to glucagon, VIP, and GIP.

Back 45

b. Secretin opposes the action of CCK on the pancreas.

Front 46

GIP:
a. Is produced by K cells of the gastric mucosa.
b. Secretion is stimulated by glucose and fat in the duodenum.
c. Inhibits pancreatic insulin release.
d. Markedly stimulates intestinal secretion of electrolytes and water.
e. Is also known as gastrin-independent insulinotropic peptide.

Back 46

b. Secretion is stimulated by glucose and fat in the duodenum.

Front 47

Select the FALSE statement below regarding vasoactive intestinal polypeptide:
a. It is found in neurons of the GI tract and brain and in cholinergic fibers of the ANS.
b. It relaxes intestinal smooth muscle, including sphincters.
c. It inhibits gastric acid secretion.
d. It may cause severe diarrhea when present in the circulation in large amounts.
e. It contains 228 amino acid residues.

Back 47

e. It contains 228 amino acid residues. (really 28)

Front 48

Which one of the following GI hormones appears to increase secretion of Cl- into the intestinal lumen?
a. Guanylin
b. Neurotensin
c. Motilin
d. Pancreatic polypeptide
e. Substance P

Back 48

a. Guanylin