Which GI hormone stimulates pancreatic enzyme secretion and bile ejection?

• A. Cholecystokinin
• B. Secretin
• C. Gastrin
• D. Vasoactive intestinal peptide

Answer: (A)

Cholecystokinin is released by I cells in the duodenum in response to fats and amino acids in chyme. It has two key actions that fit this question: it stimulates pancreatic acinar cells to secrete digestive enzymes (like amylase, lipase, and proteases) and it causes the gallbladder to contract, ejecting bile into the duodenum (through relaxation of the sphincter of Oddi). This coordinated release helps digest fats and proteins and deliver enzymes and bile where they’re needed.

Secretin mainly promotes bicarbonate-rich pancreatic and bile secretions to neutralize acid, not enzyme secretion or bile ejection. Gastrin mainly increases gastric acid production in the stomach, not pancreatic enzymes or bile flow. VIP influences intestinal secretion and motility but is not the primary driver of bile release with pancreatic enzyme output.