A 50-year-old man who is an alcoholic suffers recurrent bouts of pancreatitis that reduce output of pancreatic enzymes after ingestion of a mixed meal.
He also presents with diarrhea, and his stools contain high levels of triglycerides but no intact starch. Duodenal aspirates obtained after a meal likewise reveal that starch is being digested appropriately. Assuming the output of all pancreatic enzymes is impaired during pancreatitis, what structure(s) supply an alternate source of enzymatic activity capable of starch digestion?
A. Brunner's glands
B. brush border of enterocytes
C. gallbladder
D. parietal cells
E. chief cells
F. salivary glands
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Question 2) A patient with severe Crohn's disease undergoes resection of her terminal ileum.
After recovering from the surgery, she develops chronic diarrhea that is treated effectively with cholestyramine (a resin that can bind bile acids). Assuming her Crohn's disease has not recurred, the diarrhea in the patient can most likely be attributed to loss of which of the following membrane proteins?
A. SGLT1
B. CFTR
C. NBC1
D. Na+,K+-ATPase
E. ASBT
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Question 3) A scientist develops a mouse that lacks the ability to express CCK1 receptors. Compared to a normal mouse, which of the following would be expected to be increased?
A. gastric acid secretion
B. gallbladder contraction after a meal
C. cytosolic Ca++ in pancreatic acinar cells
D. firing of duodenal vagal afferents when food is in the lumen
E. gastric emptying
F. histamine release from ECL cells
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Question 4) A 20-year-old African American woman comes to her physician complaining of bloating, gas, diarrhea, and cramping pain that have occurred approximately 2-3 times per week for the past 2 months.
The doctor asks her to keep a diary of her diet and symptoms, which reveals that the symptoms most often occur after ingesting dairy products. The patient most likely has a relative deficiency of which of the following molecules in the brush border of her enterocytes?
A. sucrase/isomaltase
B. SGLT1
C. GLUT5
D. enterokinase
E. GLUT2
F. lactase
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Question 5) A 60-year-old woman who is hospitalized during recovery from a hysterectomy does not have a bowel movement for several days while eating solid foods.
Because intestinal obstruction is suspected, she is returned to the OR for an exploratory laparotomy. The pattern of motility most likely to be observed in her gastrointestinal tract during the surgery can best be described as:
A. peristalsis
B. segmentation
C. retroperistalsis
D. spasm
E. ileus
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Question 6) A 30-year-old man is referred to a gastroenterologist for evaluation of persistent dyspepsia (indigestion).
He is noted to have other symptoms, including flushing and hypotension, and following a bone marrow biopsy, is diagnosed with systemic mastocytosis (an excessive proliferation of histamine-containing mast cells). An increased propensity for gastric and duodenal ulcers in this patient is likely ascribable to overproduction of which of the following second messengers in gastric parietal cells?
A. calcium
B. inositol trisphosphate
C. diacyglycerol
D. cGMP
E. cAMP
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Question 7) Three medical students (X, Y, and Z) studying for their physiology final develop headaches.
Student X takes a regular aspirin with a glass of water; Y takes an enteric coated aspirin with a glass of water, and Z takes an enteric coated aspirin with a glass of milk (an enteric coating is one that dissolves only when the pH is above 6). Assuming that headache relief is proportional to plasma aspirin concentrations, and that Xt, Yt, and Zt are the times until relief is experienced by the respective students, which of the following best represents the relationship between Xt, Yt, and Zt?
A. Xt = Yt = Zt
B. Xt > Yt = Zt
C. Xt < Yt < Zt
D. Xt = Yt > Zt
E. Xt > Yt > Zt
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Question 8) A patient with severe vertigo secondary to an inner ear infection suffers from a protracted bout of vomiting. She will be most at risk for systemic symptoms related to reduced plasma concentration of which of the following electrolytes?
A. HCO3-
B. Cl-
C. Na+
D. H+
E. K+
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Question 9) In a diagnostic test, a gastroenterologist uses an endoscope to deliver a bolus of dilute acid into the distal esophagus.
The bolus is sufficient to cause esophageal dilatation. In a normal individual, the bolus will be cleared from the esophagus predominantly by which of the following?
A. primary peristalsis
B. swallowing
C. secondary peristalsis
D. relaxation of the upper esophageal sphincter
E. receptive relaxation
F. gravity
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Question 10) A 50-year-old male patient comes to his primary care physician complaining of a chronic burning sensation in his chest.
The pain is worse when lying down at night after a large meal, and can be alleviated to some degree by the use of over-the-counter antacids. The pain experienced by the patient is most likely due to dysfunction of which of the following gastrointestinal structures?
A. lower esophageal sphincter
B. pylorus
C. salivary glands
D. pancreas
E. gallbladder
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