Hydrochloric acid in stomach lumen (HCl)

Hydrochloric acid in the stomach lumen is produced by parietal cells lining the stomach through the action of H^+/K^+ ATPase (the proton pump)[5][7][10]. This creates a highly acidic environment (pH 1–2), essential for digesting proteins, activating digestive enzymes (notably pepsin), and protecting against ingested pathogens[2][3][10]. Acid secretion is regulated by complex neural, hormonal, and paracrine signals, primarily acetylcholine, gastrin, and histamine stimulation of parietal cells[5][9]. Therapeutic control of gastric acid involves drugs that act primarily on the parietal cell or acid itself, but the acid as found in the lumen is not a drug target per se. Excess, reduced, or misregulated acid is implicated in a range of gastrointestinal diseases[5][10].

Other names

Gastric acidStomach acidGastric hydrochloric acid

Proton pump inhibitors inhibit the H^+/K^+ ATPase in parietal cells, blocking acid secretion[5][10] H2 receptor antagonists block histamine stimulation of parietal cells, reducing acid secretion[5][10] Antacids neutralize hydrochloric acid by simple acid-base reaction in the stomach lumen Potassium-competitive acid blockers inhibit the K^+-binding site of the H^+/K^+ ATPase