Select the best answer:
- 1.
If a peptide belonging to the gastrin/cholecystokinin (CCK) family and having a sulfated tyrosyl residue in the seventh position from the C-terminus is desulfated, the most likely consequence for activity of the peptide will be
- a.
a pattern of activity identical to that of gastrin.
- b.
no change in pattern of activity.
- c.
increased ability to stimulate gallbladder contraction.
- d.
decreased ability to stimulate gastric acid secretion.
- e.
a pattern of activity identical to that of CCK.
- a.
- 2.
Gastrointestinal (GI) hormones
- a.
stimulate their target cells from the luminal side of the gut.
- b.
are for the most part inactivated as they pass through the liver.
- c.
are released from discrete glands within the mucosa of the GI tract.
- d.
pass through the liver and heart before reaching their targets.
- e.
are bound to plasma proteins in the blood.
- a.
- 3.
Cholecystokinin
- a.
stimulates gastric emptying.
- b.
is released by vagal stimulation.
- c.
is released by protein and fat in the proximal small bowel.
- d.
is released by distention when food enters the small bowel.
- e.
is an important stimulator of gastric acid secretion.
- a.
- 4.
Which of the following is not true about gastrinoma (Zollinger-Ellison syndrome)?
- a.
Patients usually present with gastric ulcer.
- b.
Patients develop diarrhea.
- c.
Patients often have fat in their stools.
- d.
Symptoms disappear after total gastrectomy.
- e.
Following secretin injection, the levels of gastrin in the serum increase.
- a.
- 5.
Stimulation of an intrinsic nerve in the intestine causes contraction of an intestinal muscle cell through the release of which neurotransmitter?
- a.
Acetylcholine (ACh)
- b.
Nitric oxide (NO)
- c.
Norepinephrine
- d.
Somatostatin
- e.
Vasoactive intestinal peptide (VIP)
- a.
- 6.
A nerve ending that releases NO onto a smooth muscle cell of the jejunum is injected with a dye that spreads throughout the nerve. The nerve cell body labeled by the dye most likely will be located in the
- a.
brain.
- b.
celiac ganglion.
- c.
myenteric plexus.
- d.
sacral region of the spinal cord.
- e.
thoracic region of the spinal cord.
- a.
- 7.
A muscle cell that has no striations and a ratio of thin to thick filaments of 15:1 most likely would be found in which region of the gastrointestinal tract?
- a.
External anal sphincter
- b.
Lower esophageal sphincter (LES)
- c.
Pharynx
- d.
Tongue
- e.
Upper esophageal sphincter (UES)
- a.
- 8.
In the presence of drug X, application of ACh to a bundle of gastric muscle cells causes membrane action potentials, an increase followed by a decrease in intracellular free calcium, but no contractile response. Drug X most likely is inhibiting which step in the contraction-relaxation process?
- a.
Activation of myosin light chain kinase
- b.
Binding of ACh with membrane receptors
- c.
Opening of membrane calcium channels
- d.
Opening of sarcoplasmic reticulum calcium channels
- e.
Spread of excitation among muscle cells
- a.
- 9.
A lesion is made that results in loss of primary peristaltic contractions of the pharynx and esophagus, but secondary peristalsis of the lower esophagus occurs on distention of the esophageal body. The lesion most likely is in the
- a.
cortical region of the brain.
- b.
cricopharyngeal muscle.
- c.
enteric nerves.
- d.
nucleus ambiguus of the vagus.
- e.
pharyngeal muscle.
- a.
- 10.
A segment of esophagus is removed and placed in a tissue bath. The circular muscle in the segment contracts tonically and relaxes on stimulation of the nerves intrinsic to the segment. The segment is most likely from which region of the esophagus?
- a.
Distal body of the esophagus
- b.
LES
- c.
Middle body of the esophagus
- d.
Proximal body of the esophagus
- e.
UES
- a.
- 11.
A catheter that monitors pressure at its tip is inserted through the nose and passed an unknown distance. Between swallows it records a pressure that is subatmospheric and fluctuates during the respiratory cycle, decreasing during inspiration and increasing during expiration. In which region is the catheter tip most likely located?
- a.
Esophageal body above the diaphragm
- b.
Esophageal body below the diaphragm
- c.
LES
- d.
Orad region of the stomach
- e.
UES
- a.
- 12.
A patient experiences gastric “fullness” after eating only a small quantity of food. Manometry reveals normal peristalsis in both the upper and lower esophagus but no receptive relaxation of the orad stomach. These findings are best explained by a defect in the
- a.
nucleus ambiguus of the brainstem.
- b.
dorsal motor nucleus of the brainstem.
- c.
vagal nerves.
- d.
enteric nerves.
- e.
celiac ganglion.
- a.
- 13.
Contractions of the orad stomach, proximal and distal antrum, pylorus, and proximal duodenum are monitored in a subject during the emptying of two meals that are identical except for their fat content. Compared with the low-fat meal, the meal high in fat would elicit
- a.
a decrease in the force of pyloric contractions.
- b.
an increase in the force of peristaltic antral contractions.
- c.
an increase in the number of peristaltic antral contractions.
- d.
an increase in the number of segmenting duodenal contractions.
- e.
an increase in the number of tonic contractions of the orad stomach.
- a.
- 14.
Slow waves are recorded from the orad stomach, proximal and distal antrum, and proximal duodenum in a fasted subject. Slow waves recorded during the burst phase of the migrating motor complex (MMC), compared with slow waves recorded during the relaxed phase, are characterized by
- a.
a decrease in the apparent propagation velocity of antral slow waves.
- b.
a decrease in the frequency of duodenal slow waves.
- c.
an increase in the amplitude of antral slow waves.
- d.
an increase in the frequency of antral slow waves.
- e.
the occurrence of slow waves in the orad stomach.
- a.
- 15.
Compared with the gastric motility response to a meal in an individual with intact vagus nerves, the response in an individual whose vagus nerves have been cut at a level just above the diaphragm would be characterized by
- a.
decreased emptying rate of liquids.
- b.
decreased emptying rate of solids.
- c.
increased accommodation of the meal.
- d.
increased mechanical reduction of food particle size.
- e.
increased mixing of contents.
- a.
- 16.
The rate of gastric emptying of a mixed meal of solid foods and liquids would be decreased by
- a.
blocking activation of receptors in the duodenal mucosa.
- b.
enhanced tonic contraction of the orad stomach.
- c.
infusing an isotonic solution of sodium chloride into the duodenum.
- d.
infusing an isotonic solution of sodium chloride into the stomach.
- e.
infusing an isotonic solution of sodium oleate into the duodenum.
- a.
- 17.
A patient experiences a rapid rate of transit of contents from the duodenum to the cecum. What characteristic would contractions recorded at various loci of the small intestine exhibit during this time?
- a.
Frequency greater than that of the slow wave
- b.
Low in force
- c.
Mostly peristaltic
- d.
Mostly segmenting
- e.
Mostly tonic
- a.
- 18.
Intravenous injection of a hormone initiates a phase of intense sequential contractions of the proximal duodenum that appears to migrate slowly toward the cecum. Which hormone was most likely injected?
- a.
CCK
- b.
Gastrin
- c.
Motilin
- d.
Secretin
- e.
VIP
- a.
- 19.
A region of the intestine contracts weakly on stimulation of its extrinsic nerves. Distention of the region elicits a peristaltic reflex, but with weak contractions. Slow wave activity is absent. Taken together, these findings suggest a disorder of the
- a.
enteric nerves.
- b.
parasympathetic nerves.
- c.
release of motilin.
- d.
smooth muscle cells.
- e.
sympathetic nerves.
- a.
- 20.
A normal subject’s small intestinal contractions are recorded from three loci spaced 5 cm apart. Over a period of 2 hours, contractions occur at each site seemingly at random, with the interval between any two contractions being 5 seconds or a multiple of 5 seconds. Only rarely do contractions at the three loci seem to be in sequence. These data indicate that
- a.
contractions are being recorded from the ileum.
- b.
the subject is in a fasted state.
- c.
every slow wave is being accompanied by a contraction.
- d.
the contractions are causing rapid aboral transit of contents.
- e.
the contractions are mostly of the segmenting type.
- a.
- 21.
Intraluminal pressure is monitored from a region of the colon that exhibits a relatively constant resting pressure of about 20 mm Hg. When an adjacent region of the colon is distended, resting pressure falls to near 0 and then increases slowly back toward 20 mm Hg even though the distention persists. The region being monitored is most likely the
- a.
ascending colon.
- b.
external anal sphincter.
- c.
ileocecal sphincter.
- d.
internal anal sphincter.
- e.
transverse colon.
- a.
- 22.
Segmental contractions of the colon
- a.
increase in frequency in response to increased circulating levels of epinephrine.
- b.
occur more often than do peristaltic contractions of the colon.
- c.
occur at a higher frequency in the sigmoid colon than in the rectum.
- d.
occur at a frequency that is higher than that for slow waves in the same region.
- e.
are accompanied by the loss of haustral markings.
- a.
- 23.
Relaxation of the ileocecal sphincter will occur during each of the following except
- a.
eating a meal.
- b.
distention of the ileum.
- c.
distention of the colon.
- d.
injection of gastrin.
- e.
injection of CCK.
- a.
- 24.
In a patient in whom resting tone of the internal anal sphincter is normal, distention of the rectum induces normal relaxation of the internal anal sphincter, no change in tone of the external anal sphincter, and no sensation of the urge to defecate. These findings are consistent with the finding of damage to the
- a.
enteric nerves.
- b.
internal anal sphincter.
- c.
vagus nerve.
- d.
spinal cord.
- e.
transverse colon.
- a.
- 25.
The digestive action of saliva on starch results from
- a.
lactoferrin.
- b.
lingual lipase.
- c.
ptyalin.
- d.
kallikrein.
- e.
bradykinin.
- a.
- 26.
At high rates of secretion, compared with low rates, saliva would have a lower concentration of
- a.
Na + .
- b.
water.
- c.
Cl − .
- d.
<SPAN role=presentation tabIndex=0 id=MathJax-Element-1-Frame class=MathJax style="POSITION: relative" data-mathml='HCO3−’>HCO−3HCO3−
HCO 3 −
- a.
- 27.
All of the following are characteristic of saliva except that
- a.
it has a high K + concentration.
- b.
there is a large volume of secretion relative to the weight of the glands.
- c.
both parasympathetic and sympathetic stimulation increase its flow.
- d.
it is hypotonic.
- e.
it is primarily regulated by hormones.
- a.
- 28.
Salivary secretion is inhibited by
- a.
smell.
- b.
taste.
- c.
nausea.
- d.
pressure of food in the mouth.
- e.
sleep.
- a.
- 29.
Which of the following substances or combinations will produce the highest rate of acid secretion? (Each compound is given at its half maximal dose.)
- a.
Histamine
- b.
Gastrin
- c.
Gastrin plus secretin
- d.
ACh
- e.
Histamine plus gastrin
- a.
- 30.
Acid secretion during the cephalic response to a meal
- a.
fails to occur when the antrum is acidified.
- b.
is triggered by the entrance of food into the stomach.
- c.
is prevented by vagotomy.
- d.
is inhibited by insulin injection.
- e.
is stimulated only by ACh acting on the parietal cells.
- a.
- 31.
Following the administration of histamine to a fasting individual, all of the following will occur within the parietal cells except
- a.
a decreased number of tubulovesicles.
- b.
increased carbonic anhydrase activity.
- c.
increased H + ,K + -adenosine triphosphatase (ATPase) activity.
- d.
an increased number of mitochondria.
- e.
an increased area devoted to the intracellular canaliculus.
- a.
- 32.
According to the two-component hypothesis for gastric acid secretion, the H + concentration in gastric secretion increases with the rate of secretion because
- a.
the volume of the oxyntic component increases.
- b.
the concentration of H + being secreted by the parietal cells increases.
- c.
the volume of the nonoxyntic component decreases.
- d.
the secretion of Na + is inhibited.
- e.
the secretion becomes hypertonic.
- a.
- 33.
Antral gastrin release is stimulated by all of the following except
- a.
bombesin gastrin-releasing peptide (GRP).
- b.
ACh.
- c.
fat in the stomach.
- d.
protein digestion products in the stomach.
- e.
distention of the antrum.
- a.
- 34.
The presence of acid (pH <3) in the duodenum
- a.
inhibits gastrin release via somatostatin.
- b.
increases pancreatic bicarbonate secretion.
- c.
decreases bile production.
- d.
increases gastric acid secretion.
- e.
inhibits pancreatic enzyme secretion.
- a.
- 35.
In someone with a total absence of gastric parietal cells, one would expect to find each of the following except
- a.
decreased digestion of dietary protein.
- b.
decreased absorption of vitamin B 12 .
- c.
little or no pepsin activity.
- d.
increased growth of gut bacteria.
- e.
lower than normal pancreatic bicarbonate secretion.
- a.
- 36.
Administration of a drug that blocks the H + ,K + -ATPase of the parietal cells of a secreting stomach
- a.
will have no effect on the volume of secretion.
- b.
will increase the concentration of H + in the secretion.
- c.
will decrease the concentration of Na + in the secretion.
- d.
will decrease the pH of the gastric venous blood.
- e.
will decrease the potential difference across the stomach.
- a.
- 37.
The interruption of vagal afferent fibers from the stomach would
- a.
decrease the acid secretory response to sham feeding.
- b.
decrease the release of gastrin by digested protein.
- c.
decrease acid secretion in response to distention.
- d.
decrease the release of somatostatin.
- e.
increase acid secretion in response to histamine.
- a.
- 38.
Between meals, when the stomach is empty of food,
- a.
it contains a large volume of juice with pH approximately equal to 5.
- b.
gastrin release is inhibited by a strongly acidic solution.
- c.
it contains a small volume of gastric juice with a pH near neutral.
- d.
bombesin acts on the parietal cells to inhibit secretion.
- e.
it secretes large volumes of weakly acidic juice.
- a.
- 39.
During the cephalic phase
- a.
secretin stimulates pepsin secretion.
- b.
CCK stimulates pancreatic enzyme secretion.
- c.
ACh stimulates the G cell to release gastrin.
- d.
bombesin stimulates parietal cell secretion.
- e.
ACh stimulates pancreatic enzyme secretion.
- a.
- 40.
In humans, maximal rates of pancreatic bicarbonate secretion in response to a meal result from
- a.
the effects of small amounts of secretin being potentiated by ACh and CCK.
- b.
large amounts of secretin released from the duodenal mucosa.
- c.
VIP acting on the ductule cells.
- d.
potentiation between CCK and ACh released from vagovagal reflexes.
- e.
potentiation between small amounts of secretin and gastrin.
- a.
- 41.
Vagal stimulation
- a.
potentiates the effect of CCK on pancreatic acinar cells.
- b.
directly stimulates pancreatic enzyme secretion.
- c.
releases CCK from the duodenal mucosa.
- d.
inhibits the effect of secretin on pancreatic ductule cells.
- e.
releases secretin from duodenal mucosa.
- a.
- 42.
Pancreatic enzyme secretion
- a.
contains enzymes for the digestion of fat and protein but not carbohydrate.
- b.
is primarily stimulated by secretin.
- c.
is stimulated by pancreatic polypeptide.
- d.
originates from the ductule cells.
- e.
occurs primarily during the intestinal phase of the secretory response.
- a.
- 43.
Pancreatic bicarbonate
- a.
is secreted primarily from acinar cells.
- b.
is secreted in quantities approximately equal to those of gastric acid.
- c.
is stimulated primarily during the gastric phase of digestion.
- d.
secretion causes an increase in the pH of pancreatic venous blood.
- e.
ion concentrations in pancreatic juice decrease with increasing rates of volume secretion.
- a.
- 44.
Pancreatic enzymes
- a.
are synthesized in response to a secretory stimulus.
- b.
are stored in Golgi vesicles.
- c.
are secreted in response to carbohydrate in the duodenum.
- d.
are secreted in response to sham feeding.
- e.
are involved in the breakdown of disaccharides.
- a.
- 45.
A sample of bile taken from the gallbladder is compared with a sample of bile collected as it is being secreted from the liver. Compared with hepatic bile, the gallbladder bile will differ in that its
- a.
bile salt concentration will be less.
- b.
cholesterol–bile salt ratio will be greater.
- c.
osmolality will be greater.
- d.
phospholipid concentration will be less.
- e.
potassium concentration will be greater.
- a.
- 46.
Bile acid A has a greater solubility in intestinal fluid than does bile acid B. Compared with bile acid B, bile acid A is more likely to be
- a.
a secondary bile acid.
- b.
a trihydroxy rather than a dihydroxy bile acid.
- c.
absorbed passively in the jejunum.
- d.
unconjugated.
- e.
undissociated.
- a.
- 47.
When the distal ileum is removed, there will be an increase in bile acid
- a.
levels in hepatic venous blood.
- b.
levels in portal venous blood.
- c.
secretion by hepatocytes.
- d.
storage in the gallbladder.
- e.
synthesis by hepatocytes.
- a.
- 48.
As the bile secreted by the hepatocytes flows through the hepatic ducts on the way to the gallbladder, there is an increase in bile
- a.
bicarbonate concentration.
- b.
bilirubin content.
- c.
chloride concentration.
- d.
H + concentration.
- e.
osmolality.
- a.
- 49.
The rate of absorption of free galactose in the small intestine, initially occurring at a submaximal rate, would be
- a.
increased by adding an equal amount of glucose to the lumen.
- b.
decreased by adding amino acids to the lumen.
- c.
decreased by adding fructose to the lumen.
- d.
increased by the addition of trehalose to the lumen.
- e.
decreased by hypoxia in the enterocytes.
- a.
- 50.
Which of the following enzymes is located in the brush border and plays a role in protein digestion?
- a.
α-Dextrinase
- b.
Carboxypeptidase A
- c.
Pepsin
- d.
Enterokinase
- e.
Lactase
- a.
- 51.
Colipase facilitates fat assimilation by
- a.
digesting triglycerides.
- b.
transporting fatty acids across cell membranes.
- c.
preventing the inactivation of lipase by bile salts.
- d.
converting prolipase to lipase.
- e.
binding fatty acids and monoglycerides after they have been absorbed by the enterocytes.
- a.
- 52.
Most medium-chain fatty acids do not appear in chylomicrons because
- a.
they are not absorbed by enterocytes.
- b.
they are transported by fatty acid–binding proteins.
- c.
they do not bind to apoproteins.
- d.
triglycerides containing them are not digested by pancreatic lipase.
- e.
they are absorbed directly into the blood.
- a.
- 53.
In the absence of enterokinase, one would also expect a decrease in the activity of
- a.
pepsin.
- b.
lipase.
- c.
chymotrypsin.
- d.
amylase.
- e.
sucrase.
- a.
- 54.
Amino acids
- a.
are primarily absorbed in the distal gut.
- b.
are, for the most part, absorbed by passive mechanisms.
- c.
compete with glucose for Na + during their absorption.
- d.
appear in the blood more rapidly when presented to the gut as small peptides rather than as free amino acids.
- e.
are produced in the lumen primarily by the action of endopeptidases.
- a.
- 55.
Each of the following acts as a good emulsifying agent except
- a.
cholesterol.
- b.
bile salts.
- c.
fatty acids.
- d.
lecithin.
- e.
dietary protein.
- a.
- 56.
Colipase
- a.
digests the ester link in 2-monoglycerides.
- b.
is a brush border enzyme.
- c.
has no enzymatic activity.
- d.
lowers the pH optimum of pancreatic lipase to match that of duodenal contents.
- e.
displaces pancreatic lipase from the surface of emulsion droplets.
- a.
- 57.
The reason that patients with a congenital absence of one of the amino acid carriers do not become deficient in that amino acid is that
- a.
the amino acid is absorbed by passive diffusion.
- b.
the amino acid can make use of other carriers.
- c.
the amino acid is absorbed by facilitated diffusion.
- d.
peptides containing the amino acid are absorbed by different carriers.
- e.
the amino acid is an essential amino acid.
- a.
- 58.
Within the enterocytes
- a.
triglycerides are resynthesized in the smooth endoplasmic reticulum.
- b.
chylomicrons are synthesized in the smooth endoplasmic reticulum.
- c.
fatty acid–binding protein transports long-chain fatty acids to the Golgi apparatus.
- d.
triglycerides are synthesized from medium- and short-chain fatty acids.
- e.
the major triglyceride resynthesis pathway makes use of dietary glycerol.
- a.
- 59.
Of the 8 to 10 L of H 2 O entering the digestive tract per day,
- a.
only 100 to 200 mL is excreted in the stool.
- b.
most comes from the diet (includes liquids).
- c.
most is absorbed in the large intestine.
- d.
gastric secretions contribute twice the volume of those from the pancreas.
- e.
most is absorbed against its own concentration gradient.
- a.
- 60.
In the small intestine, Na + is absorbed by each of the following processes except
- a.
diffusion.
- b.
coupled to amino acid absorption.
- c.
coupled to galactose absorption.
- d.
coupled to the transport of H + in the opposite direction.
- e.
coupled to the absorption of <SPAN role=presentation tabIndex=0 id=MathJax-Element-2-Frame class=MathJax style="POSITION: relative" data-mathml='HCO3−¿’>HCO−¿3HCO3−¿
HCO 3 − ¿
.
- a.
- 61.
In the distal portion of the ileum,
- a.
most fatty acids are absorbed.
- b.
Cl − is absorbed in exchange for <SPAN role=presentation tabIndex=0 id=MathJax-Element-3-Frame class=MathJax style="POSITION: relative" data-mathml='HCO3−’>HCO−3HCO3−
HCO 3 −
.
- c.
Na + absorption occurs primarily coupled to glucose and amino acids.
- d.
intrinsic factor is secreted.
- e.
K + is absorbed in exchange for Na + .
- a.
- 62.
In the small intestine each of the following is true regarding Cl − absorption except that
- a.
it occurs down its electrical gradient.
- b.
it occurs in exchange for Na + .
- c.
it occurs in exchange for <SPAN role=presentation tabIndex=0 id=MathJax-Element-4-Frame class=MathJax style="POSITION: relative" data-mathml='HCO3−¿’>HCO−¿3HCO3−¿
HCO 3 − ¿
.
- d.
it will result in the absorption of water.
- e.
it occurs along the entire length of the small bowel.
- a.
- 63.
Osmotic diarrhea may be the result of each of the following except
- a.
cholera.
- b.
lactase deficiency.
- c.
inactivation of pancreatic lipase.
- d.
Zollinger-Ellison syndrome (gastrinoma).
- e.
loss of mucosal surface area in the small intestine.
- a.
- 64.
Secretion of Cl − by the small intestine
- a.
occurs in exchange for <SPAN role=presentation tabIndex=0 id=MathJax-Element-5-Frame class=MathJax style="POSITION: relative" data-mathml='HCO3−¿’>HCO−¿3HCO3−¿
HCO 3 − ¿
.
- b.
takes place primarily in the villous cells.
- c.
is inhibited by ouabain.
- d.
produces an osmotic diarrhea.
- e.
depends on an ATPase in the brush border membrane.
- a.
Matching
- a.
Gastrin
- b.
CCK
- c.
Somatostatin
- d.
Secretin
- e.
VIP
- f.
Histamine
- a.
- 65.
Inhibits gastrin release when antrum is acidified
- 66.
Inhibits parietal cell secretion of acid when antrum is acidified
- 67.
Stimulates growth of gastric mucosa
- 68.
Released by gastrin and acts as a paracrine to stimulate acid secretion
- 69.
Stimulates gallbladder contraction in response to fat in the duodenum
- 70.
Stimulates intestinal secretion and relaxes smooth muscle
Answers
| 1. A | 17. C | 33. C | 49. E | 65. C |
| 2. D | 18. C | 34. B | 50. D | 66. C |
| 3. C | 19. D | 35. A | 51. C | 67. A |
| 4. A | 20. E | 36. D | 52. E | 68. F |
| 5. A | 21. D | 37. C | 53. C | 69. B |
| 6. C | 22. B | 38. B | 54. D | 70. E |
| 7. B | 23. C | 39. E | 55. A | |
| 8. A | 24. D | 40. A | 56. C | |
| 9. D | 25. C | 41. B | 57. D | |
| 10. B | 26. B | 42. E | 58. A | |
| 11. A | 27. E | 43. B | 59. A | |
| 12. C | 28. E | 44. D | 60. E | |
| 13. D | 29. E | 45. E | 61. B | |
| 14. C | 30. C | 46. B | 62. B | |
| 15. B | 31. D | 47. E | 63. A | |
| 16. E | 32. A | 48. A | 64. C |
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