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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 ...
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
Additional cells present include parietal cells that secrete hydrochloric acid and intrinsic factor, chief cells that secrete pepsinogen (this is a precursor to pepsin- the highly acidic environment converts the pepsinogen to pepsin), and neuroendocrine cells that secrete serotonin. [22] [citation needed]
Diagram of the digestive enzymes in the small intestine and pancreas Digestive enzymes take part in the chemical process of digestion , which follows the mechanical process of digestion. Food consists of macromolecules of proteins, carbohydrates, and fats that need to be broken down chemically by digestive enzymes in the mouth , stomach ...
Gastric juice is the combination of gastric gland secretions including the main component of hydrochloric acid (gastric acid), gastric lipase and pepsinogen. [3] Once in the stomach pepsinogen is changed by gastric acid to the digestive enzyme pepsin adding this enzyme to the gastric juice. [4] Gastric acid secretion is produced in several steps.
Gastrin is a linear peptide hormone produced by G cells of the duodenum and in the pyloric antrum of the stomach.It is secreted into the bloodstream. The encoded polypeptide is preprogastrin, which is cleaved by enzymes in posttranslational modification to produce progastrin (an intermediate, inactive precursor) and then gastrin in various forms, primarily the following three:
The enteroendocrine cells also secrete glucose dependent insulinotropic peptide. Originally called gastric-inhibitory peptide, it is no longer thought to have a significant effect on the stomach, but to be more concerned with stimulating insulin secretion in preparation for processing the nutrients about to be absorbed by the small intestine. [1]
In mammals, HCl is secreted into the stomach by parietal cells, while chief cells secrete pepsinogen. [7] In birds, the gastric glands of the proventriculus secrete both the HCl and the pepsinogen. [8] Since pepsinogen is a zymogen, it is then activated to pepsin by the HCl.