A 42-year-old man admitted after a binge of alcohol develops severe epigastric pain radiating to the back. Imaging confirms acute pancreatitis. The pathogenesis involves premature intrapancreatic activation of zymogens because the normal activating cascade begins when:
- A Enteropeptidase on the duodenal brush border converts trypsinogen to trypsin, which then activates other proenzymes ✓
- B Pepsin activates trypsinogen in the pancreatic acinar cells
- C Low duodenal pH directly autocatalyses chymotrypsinogen
- D Pancreatic secretory trypsin inhibitor activates procarboxypeptidase A
Correct answer: A. Enteropeptidase on the duodenal brush border converts trypsinogen to trypsin, which then activates other proenzymes
Explanation
Enteropeptidase (enterokinase), located on the duodenal brush border, cleaves trypsinogen to trypsin. Trypsin then activates the remaining pancreatic zymogens including chymotrypsinogen, proelastase, procarboxypeptidases and prophospholipase B2. In pancreatitis these proteases become active prematurely within the gland and digest pancreatic tissue. Pepsin acts in the stomach and cannot reach zymogens inside acinar cells, making option B impossible anatomically.
Reference: Lippincott's Illustrated Reviews: Biochemistry, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.