Which gastric gland cells secrete hydrochloric acid and intrinsic factor, and what stimulates them?

• A. Parietal cells; gastrin, histamine, and acetylcholine
• B. Chief cells; secretin and CCK
• C. G cells; vagal stimulation
• D. Mucous neck cells; prostaglandins

Answer: (A)

Parietal (oxyntic) cells in the gastric glands are the ones that secrete both hydrochloric acid and intrinsic factor. They are stimulated by three main signals: gastrin, histamine, and acetylcholine. Gastrin, released from G cells in the antrum in response to amino acids and stomach stretch, acts on parietal cells to boost acid secretion. It also prompts nearby enterochromaffin-like cells to release histamine, which then binds to H2 receptors on parietal cells to further increase acid production. Acetylcholine, released from vagal nerve endings during the cephalic and gastric phases, directly stimulates parietal cells via muscarinic receptors and also enhances histamine release. This combination drives robust acid secretion, and intrinsic factor produced by the same parietal cells is essential for vitamin B12 absorption.