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The secretion is a complex and relatively energetically expensive process. Parietal cells contain an extensive secretory network (called canaliculi) from which the hydrochloric acid is secreted into the lumen of the stomach. The pH of gastric acid is 1.5 to 3.5 in the human stomach lumen, a level maintained by the proton pump H + /K + ATPase. [1]
Their secretions make up the digestive gastric juice. The gastric glands open into gastric pits in the mucosa. The gastric mucosa is covered in surface mucous cells that produce the mucus necessary to protect the stomach's epithelial lining from gastric acid secreted by parietal cells in the glands, and from pepsin, a secreted digestive enzyme ...
This fluid is composed of four primary components: ions, digestive enzymes, mucus, and bile. About half of these fluids are secreted by the salivary glands, pancreas, and liver, which compose the accessory organs and glands of the digestive system. The rest of the fluid is secreted by the GI epithelial cells.
The parietal cells in the fundus of the stomach, produce a glycoprotein called intrinsic factor which is essential for the absorption of vitamin B12. Vitamin B12 (cobalamin), is carried to, and through the stomach, bound to a glycoprotein secreted by the salivary glands – transcobalamin I also called haptocorrin, which protects the acid ...
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
The chief and parietal cells produce and secrete mucus (F) to protect the lining of the stomach (C) against the harsh pH of stomach acid. The mucus is basic, while the stomach acid (A) is acidic. In the human digestive system, mucus is used as a lubricant for materials that must pass over membranes, e.g., food passing down the esophagus.
Alkaline mucus exists in the human eye, stomach, saliva, and cervix. [5] In the stomach, alkaline mucus is secreted by gastric glands in the gastric mucosa of the stomach wall. [6] Secretion of alkaline mucus is necessary to protect the mucous membrane of the stomach from acids released during digestion. [6]
Gastric secretion at this phase rises to 40% of maximum rate. Acidity in the stomach is not buffered by food at this point and thus acts to inhibit parietal (secretes acid) and G cell (secretes gastrin) activity via D cell secretion of somatostatin. The gastric phase takes 3 to 4 hours.