GI System MCAT Practice Question
A 58-year-old woman undergoes laparoscopic cholecystectomy for symptomatic cholelithiasis. Two weeks postoperatively, she develops chronic diarrhea with fatty, foul-smelling stools. Laboratory studies show normal pancreatic enzyme levels and normal fecal chymotrypsin. Fat-soluble vitamin absorption is decreased. A small bowel biopsy shows normal mucosa and intact intestinal brush border. The patient's symptoms are attributed to impaired fat digestion and absorption secondary to gallbladder removal. Which of the following best explains the molecular basis for the postoperative malabsorption of dietary fat?
Answer choices
- AReduced pancreatic lipase synthesis due to loss of gallbladder-derived growth factors
- BIncreased small intestinal pH from unopposed bicarbonate secretion, reducing lipase activity
- CDecreased formation of mixed micelles due to insufficient bile salt concentration in the intestinal lumenCorrect answer
- DImpaired pancreatic enzyme activation by intestinal enteropeptidase from chronic bile acid loss
- EEnhanced degradation of triglycerides by excessive colonic bacterial lipase activity
- FReduced expression of apical intestinal fatty acid transporters from decreased cholecystokinin signaling
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