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Gastric acid or stomach acid is the acidic component – hydrochloric acid of gastric juice, produced by parietal cells in the gastric glands of the stomach lining. In humans, the pH is between one and three, much lower than most other animals, but is very similar to that of carrion eating carnivores , needing protection from ingesting pathogens .
It consists mainly of hydrochloric acid and acidifies the stomach content to a pH of 1 to 2. [36] [37] Chloride (Cl −) and hydrogen (H +) ions are secreted separately in the stomach fundus region at the top of the stomach by parietal cells of the gastric mucosa into a secretory network called canaliculi before it enters the stomach lumen. [38]
A canaliculus is an adaptation found on gastric parietal cells. It is a deep infolding, or little channel, which serves to increase the surface area, e.g. for secretion. The parietal cell membrane is dynamic; the numbers of canaliculi rise and fall according to secretory n
When performing the Heidelberg test, the patient swallows a small electronic device about the size of a vitamin capsule. This device tracks acid levels in the stomach as the patient swallows small amounts of baking soda, which neutralises the hydrochloric acid in the stomach. If the acid level does not return to normal after the baking soda is ...
Metabolic alkalosis is an acid-base disorder in which the pH of tissue is elevated beyond the normal range (7.35–7.45). This is the result of decreased hydrogen ion concentration, leading to increased bicarbonate (HCO − 3), or alternatively a direct result of increased bicarbonate concentrations.
In 1916, Popielski described histamine as a gastric secretagogue of hydrochloric acid. William Beaumont was an army surgeon who in 1825, was able to observe digestion as it took place in the stomach. [55] This was made possible by experiments on a man with a stomach wound that did not fully heal leaving an opening into the stomach.
The gastric hydrogen potassium ATPase or H + /K + ATPase is the proton pump of the stomach.It exchanges potassium from the intestinal lumen with cytoplasmic hydronium [2] and is the enzyme primarily responsible for the acidification of the stomach contents and the activation of the digestive enzyme pepsin [3] (see gastric acid).
The hormone gastrin and the vagus nerve trigger the release of both pepsinogen and HCl from the stomach lining when food is ingested. Hydrochloric acid creates an acidic environment, which allows pepsinogen to unfold and cleave itself in an autocatalytic fashion, thereby generating pepsin (the active form). Pepsin cleaves the 44 amino acids ...