Pepsinogen chief cell secretion

Chief Cells Secrete proenzyme pepsinogen (pepsin)... 

Gastrin is a hormone produced by gastric endocrine tissue — specifically, the G cells in the pyloric gland area. It is released into the blood and carried back to the stomach. The major function of gastrin is to enhance acid secretion by directly stimulating parietal cells (HC1) and chief cells (pepsinogen). Gastrin also stimulates the local release of histamine from enterochromaf-fin-like cells in the wall of the stomach. Histamine stimulates parietal cells to release HC1. 

Xie G et al Cholinergic agonist-induced pepsinogen secretion from murine gastric chief cells is mediated by Mi and M3 muscarinic receptors. Am J Physiol 2005 289 G521. 

Pepsinogen secretion from gastric chief cells Cholinergic vasodilatation in cerebral vessels... 

The stomach environment is acidic as a result of HC1 secretion by the parietal cells. The acidic pH serves to denature many proteins, thus making them susceptible to proteolysis. The chief cells of the stomach produce pepsinogen, which is activated to pepsin by the HC1 (see Table 20.3). The optimum pH of peptic activity is around 2, and pepsin is inactivated at neutrality. Another stomach enzyme is rennin or chymosin, which is present in infants but not in adults. It removes a glycopeptide from milk-K-casein, disrupting the casein micelle and promoting milk protein coagulation and digestion. 

Pepsinogen is secreted by chief cells in the gastric mucosa and is the precursor of the protease enzyme pepsin. 

The oxyntic gland is the secretory unit of the gastric mucosa. The acid-secreting parietal cells are located in the wall of its midsection. In addition to parietal cells, these glands consist of mucous-secreting superficial and neck cells, pepsinogen-secreting chief cells, endocrine, and somatostatin cells [1]. 

Entry of protein in to stomach stimulates gastric mucosa to secreate the hormone gastrin. Which stimulates the secretion of hydrochloric acid by the parietal cells of gastric glands and pepsinogen by the chief cells. 

Protein digestion begins in the stomach, where protein is denatured by the low pH and is exposed to the action of pepsin. The low pH also provides the optimal H+ concentration for pepsin activity. The zymogen precursor pepsinogen (M.W. 40,000) is secreted by the chief cells and is converted to pepsin (M.W. 32,7(K)) in the acid medium by removal of a peptide consisting of 44 amino acid residues. This endopeptidase hydrolyzes peptide bonds that involve the carboxyl group of aromatic amino acid residues, leucine, methionine, and acidic residues (Table 12-5). The products consist of a mixture of oligopeptides. 

Pepsinogen, the inactive precnrsor of pepsin, is secreted by the chief cells located in the gastric fnndns (see Pig. 33-1). Pepsin is activated by acid pH (optimal pH of 1.8 to 3.5), inactivated reversibly at pH 4, and irreversibly destroyed at pH 7. Pepsin appears to play a role in the proteolytic activity involved in nicer formation. " ... 

Pepsinogen is secreted by the chief cells of the stomach. The gastric parietal cells secrete HCl. The acid in the stomach lumen alters the conformation of pepsinogen so that it can cleave itself, producing the active protease pepsin. Thus, the activation of pepsinogen is autocatalytic. 

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