|Maryville
1. What is the pathophysiological hallmark of Barrett’s esophagus?
A. Metaplasia of squamous epithelium to columnar epithelium
B. Squamous cell carcinoma in situ
C. Hypertrophy of the lower esophageal sphincter
D. Atrophy of the mucosal lining with decreased vascularity
Answer: A
Rationale: Barrett’s esophagus involves intestinal metaplasia, where the normal stratified
squamous epithelium of the esophagus is replaced by simple columnar epithelium with
goblet cells due to chronic acid exposure.
2. How does Helicobacter pylori survive the highly acidic environment of the
stomach?
A. By burrowing into the muscularis propria layer
B. By producing urease to create an alkaline microenvironment
C. By inhibiting gastrin secretion from G cells
D. By secreting a thick polysaccharide capsule that resists acid
Answer: B
Rationale: H. pylori produces the enzyme urease, which breaks down urea into ammonia
and carbon dioxide, neutralizing gastric acid in its immediate vicinity.
,3. In Zollinger-Ellison syndrome, what is the primary cause of multiple peptic
ulcers?
A. Chronic use of nonsteroidal anti-inflammatory drugs
B. Excessive gastrin secretion by a neuroendocrine tumor
C. Autoimmune destruction of parietal cells
D. Vagal nerve overstimulation of the fundus
Answer: B
Rationale: Zollinger-Ellison syndrome is characterized by gastrin-secreting tumors
(gastrinomas), leading to extreme gastric acid hypersecretion and severe peptic ulceration.
4. Which mechanism best describes the failure of the lower esophageal
sphincter (LES) to relax in achalasia?
A. Hypertrophy of the circular muscle layer
B. Loss of inhibitory neurons in the myenteric plexus
C. Overexpression of acetylcholine at the neuromuscular junction
D. Damage to the mucosal mechanoreceptors
Answer: B
Rationale: Achalasia results from the loss of ganglion cells in the myenteric plexus,
specifically those that release nitric oxide and vasoactive intestinal peptide (VIP), which are
required for LES relaxation.
5. Which of the following is a primary risk factor for the development of
cholesterol gallstones?
A. Hyperbilirubinemia due to chronic hemolysis
B. Hyposecretion of biliary salts and lecithin
C. Reduced gallbladder stasis during pregnancy
D. Increased intestinal motility in the ileum
Answer: B
, Rationale: Cholesterol stones form when bile becomes supersaturated with cholesterol,
often due to a relative deficiency in bile salts or lecithin, which normally keep cholesterol in
a soluble state.
6. What is the underlying pathophysiology of portal hypertension in liver
cirrhosis?
A. Systemic arterial vasodilation leading to high cardiac output
B. Compression of the hepatic artery by regenerating nodules
C. Decreased oncotic pressure due to hypoalbuminemia
D. Increased resistance to blood flow within the hepatic sinusoids
Answer: D
Rationale: Fibrosis and regenerating nodules in cirrhosis distort the hepatic architecture
and compress the sinusoids, increasing resistance to portal venous flow.
7. Hepatic encephalopathy is primarily attributed to the accumulation of which
neurotoxin?
A. Bilirubin
B. Ammonia
C. Urea
D. Lactate
Answer: B
Rationale: Liver failure prevents the conversion of ammonia to urea; ammonia crosses the
blood-brain barrier and impairs astrocyte function and neurotransmission.