Which hormone increases pancreatic bicarbonate secretion and inhibits gastric motility?

• A. CCK
• B. Gastrin
• C. Motilin
• D. Secretin

Answer: (D)

When the duodenum senses acidic chyme, the hormone released is secretin. Its main job is to protect the intestinal lining and create the right pH for digestion. Secretin stimulates the pancreatic duct cells to pour out bicarbonate-rich fluid, which neutralizes stomach acid as it enters the small intestine. At the same time, secretin dampens gastric activity, slowing stomach emptying so the duodenum isn’t overwhelmed with acidity.

That combination—boosting pancreatic bicarbonate secretion and slowing gastric motility—fits secretin precisely. The other options don’t do both actions together: one boosts enzyme-rich secretion or acid production, another drives motility, and another promotes overall GI movement but not bicarbonate secretion.