What triggers pancreatic bicarbonate secretion and what is its effect on pH?

• A. Secretin triggers bicarbonate secretion; neutralizes acid and raises pH toward neutrality.
• B. Gastrin triggers bicarbonate secretion; raises pH.
• C. Cholecystokinin triggers bicarbonate secretion; lowers pH.
• D. Somatostatin triggers bicarbonate secretion; maintains pH.

Answer: (A)

The key idea is that secretin is released when acid enters the small intestine. In response, secretin stimulates the pancreatic ducts to pour out a bicarbonate-rich fluid. This bicarbonate neutralizes the incoming gastric acid, raising the pH toward neutrality so pancreatic enzymes can work effectively and protect the intestinal lining. Other hormones have different primary roles—gastrin boosts stomach acid production; cholecystokinin mainly drives enzyme secretion and gallbladder contraction; somatostatin inhibits pancreatic secretions—so they don’t trigger the bicarbonate surge.