Stomach acid – among the cells of the stomach lining, the chief cells secrete pepsinogen, from which pepsin is formed when it is activated.
This is a protein-digesting enzyme. The accessory cells are located on the surface and in the neck of the gland ducts and produce mucus (mucin), which plays a protective role for the stomach’s wall.
The parietal cells (also known as covering or oxyntic cells), stimulated by pentagastrin, produce stomach-acid (hydrochloric acid) and intrinsic factor.
The G cells produce and store gastrin, an internal regulatory hormone, and are located in the middle third of the glands.
The so-called GEP cells are located at the base of the glands. The stomach homogenises swallowed food through peristaltic movement, the hydrochloric acid it produces reduces the number of bacteria, and in the acidic environment pepsin begins to digest proteins.
Some nutrients are already absorbed in the stomach.
