Which enteroendocrine cell secretes gastrin, and what is gastrin's primary action?

• A. G cells; stimulate gastric acid secretion and growth of gastric mucosa
• B. D cells; inhibit acid secretion
• C. I cells; stimulate bile secretion
• D. S cells; secrete secretin

Answer: (A)

Gastrin is produced by enteroendocrine G cells in the stomach, primarily in the antral region. Its main action is to stimulate gastric acid secretion by parietal cells and to promote growth of the gastric mucosa. It does this both directly on parietal cells and indirectly by triggering histamine release from ECL cells, which further boosts acid production. The other cells secrete different hormones: D cells release somatostatin and inhibit acid secretion; I cells release cholecystokinin (CCK), which mainly acts on the pancreas and gallbladder; S cells release secretin, which increases bicarbonate secretion. Thus, the cell and the action described correspond to gastrin’s role in promoting acid production and mucosal growth.