Hydrochloric acid is abbreviated HCl. It’s secreted by the parietal cells, which are the stomach epithelium cells. These cells also secrete intrinsic factor. Hydrochloric acid has many functions. It denatures proteins, makes some minerals such as iron and calcium more absorbable, converts pepsinogens into pepsin, stimulates the production of hormones in the stomach and kills bacteria. It also promotes the uptake of minerals and trace elements into the bloodstream. HCl acidifies the stomach to a pH of 1 or 2.
A thick mucus layer protects the stomach. Once the chyme leaves the stomach the intestine is protected by secretin induced buffering with sodium bicarbonate. Secretin is a peptide hormone produced by the S cells of the duodenum. It regulates the pH of the duodenum’s contents by controlling gastric acid and buffering with bicarbonate.
As we age the production of hydrochloric acid slows down. For this reason middle-aged people have more difficulty digesting their food. This is why some people question using drugs to reduce acid in the stomach to treat acid reflux. The sphincter, between the stomach and esophagus, relaxing at the wrong time causes acid reflux. This is due to things such as stress, over eating and gall bladder problems.
Gastrin is a hormone that is secreted from G cells in the stomach. It’s what stimulates gastric acid secretion and prepares the gastrointestinal tract for digestion and absorption of food.
In 1905, John Edkins first proposed the idea of the existence of a substance, which is released into the blood stream, in response to food in the stomach and circulates in the bloodstream to stimulate acid secretion. It was assumed that histamine, which is a substance that’s abundantly present in the gastric mucosa, was the mediator that stimulated acid secretion. Years later, Morton I. Grossman , et al. experimented with a dog and showed that the stimulus was a blood-borne factor, which meant it was a hormone. In 1964, R. A. Gregory and Hilda J. Tracy isolated the hormone from a hog’s stomach and it was subsequently named gastrin.
Gastrin is secreted from the G cells of the gastric mucosa and gastric antrum. The turnover of the G cells is slow. It’s stimulated by gastrin. Acid is a very strong inhibitor of G cell proliferation. That’s the reason why constant administration of omeprazole, which blocks acid secretion, results in the proliferation of G cells. If the omeprazole is suddenly discontinued, rebound hyperacidity can be the result. Don’t stop taking omeprazole suddenly. You must wean yourself off by cutting down the dose gradually. If you have any questions on weaning off of a drug talk to your pharmacist. Omeprazole is a proton pump inhibitor. That is it blocks the H+ / K+ ATPase proton pump of the stomach. It’s used in the treatment of both ulcer disease and acid reflux disease. There still remains concern that by lowering acid secretion too drastically and causing the elevation of serum gastrin levels this could be mitogenic and thus tumor promoting.