How the stomach makes Acid

The stomach is lined with parietal cells.

In response to sight, smell, taste on thought of food, the brain sends signals to activate acid production involving the neurotransmitter acetylcholine which causes the cells to change, becoming Proton Pumps that release hydrogen ions and make Hydrochloric Acid.

As food enters the stomach, the hormone, Gastrin is released due to the stretching of the stomach and the peptides and amino acids in the food. In turn Gastrin triggers Histamine release which, picked up by H2 receptors in the parietal cells, also stimulates acid production.

Somatostatin acts to inhibit acid production to maintain the correct balance of acidity by acting directly on the proton pumps as well as gastrin and histamine production.

For most people suffering acid reflux, the amount of acid produced is probably not the problem, it’s that the acid is refluxing to an unprotected location.

The mechanism by which the parietal cells produce acid is described in this article "The Parietal Cell: Mechanism of Acid Secretion."

Page last updated 02 December 2023