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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
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 .
A peptide hormone, gastrin, produced by G cells in the gastric glands, stimulates the production of gastric juice which activates the digestive enzymes. Pepsinogen is a precursor enzyme produced by the gastric chief cells, and gastric acid activates this to the enzyme pepsin which begins the digestion of proteins. As these two chemicals would ...
5-10% of gastric secretion occurs during this phase. [2] The intestinal phase is a stage in which the duodenum responds to arriving chyme and moderates gastric activity through hormones and nervous reflexes. The duodenum initially enhances gastric secretion, but soon inhibits it.
A G cell or gastrin cell is a type of cell in the stomach and duodenum that secretes gastrin. It works in conjunction with gastric chief cells and parietal cells. G cells are found deep within the pyloric glands of the stomach antrum, and occasionally in the pancreas [1] and duodenum. The vagus nerve innervates the G cells.
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]
Effects on endocrine secretion Effects on exocrine secretion Effects on motility Other effects Stimulus for release; Gastrin: G Cells in stomach ECL cells; parietal cells None Increases acid secretion, increases mucus growth Stimulates gastric contraction None Peptides and amino acids in lumen; gastrin releasing peptide and ACh in nervous reflexes
Mucous neck cells produce mucus, parietal cells secrete hydrochloric acid and intrinsic factor, chief cells secrete pepsinogen and gastric lipase. [4] The other type of gastric gland is the pyloric gland which is an endocrine gland that secretes the hormone gastrin produced by its G cells.