Which gastrointestinal peptide hormone stimulates the exocrine pancreas to secrete water and bicarbonate ions into pancreatic juice to neutralize acidic gastric chyme?
Answer and explanation
Correct answer: C. Secretin
- Step 1: The gastrointestinal mucosa contains enteroendocrine cells that secrete local regulatory peptide hormones.
- Step 2: When acidic chyme enters the duodenum, S-cells secrete secretin into the bloodstream.
- Step 3: Secretin acts on the ductal cells of the exocrine pancreas to stimulate copious secretion of water and bicarbonate ions (), raising duodenal pH to optimize pancreatic enzyme activity.
Answer
Secretin
Why not the others: 'Gastrin' is secreted by gastric G-cells and stimulates gastric glands to secrete hydrochloric acid () and pepsinogen; 'Cholecystokinin (CCK)' stimulates pancreatic acinar cells to secrete digestive enzymes and stimulates gallbladder contraction; 'Gastric Inhibitory Peptide (GIP)' inhibits gastric secretion and motility.
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