Which hormone stimulates pancreatic bicarbonate secretion and slows gastric emptying?

• A. Secretin
• B. GIP
• C. Cholecystokinin
• D. Motilin

Answer: (A)

Secretin is released when acidic chyme enters the duodenum. Its primary job is to signal the pancreas to release bicarbonate-rich fluid, which neutralizes stomach acid as it moves into the small intestine. It also slows gastric emptying, giving the intestine time to neutralize the acid before more chyme arrives. This combination—stimulating pancreatic bicarbonate secretion and delaying gastric emptying—fits best with the option named secretin. The other hormones have different main roles: some mainly promote enzyme-rich pancreatic secretions or insulin release, and others influence gut motility in ways that don’t combine bicarbonate production with a slowdown in emptying.