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Pepsin / ˈ p ɛ p s ɪ n / is an endopeptidase that breaks down proteins into smaller peptides and amino acids. It is one of the main digestive enzymes in the digestive systems of humans and many other animals, where it helps digest the proteins in food. Pepsin is an aspartic protease, using a catalytic aspartate in its active site. [2]
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 ...
The breakdown of protein begins in the stomach through the actions of hydrochloric acid, and the enzyme pepsin. The stomach can also produce gastric lipase, which can help digesting fat. The contents of the stomach are completely emptied into the duodenum within two to four hours after the meal is eaten.
Gastric chief cells are generally located deep in the mucosal layer of the stomach lining, in the fundus and body of the stomach. [2] [3] Chief cells release the zymogen (enzyme precursor) pepsinogen when stimulated by a variety of factors including cholinergic activity from the vagus nerve and acidic condition in the stomach.
Please help to improve this article by introducing more precise citations. ( February 2011 ) ( Learn how and when to remove this message ) The gastrointestinal hormones (or gut hormones ) constitute a group of hormones secreted by enteroendocrine cells in the stomach , pancreas , and small intestine that control various functions of the ...
Protein degradation differs from protein catabolism. Proteins are produced and destroyed routinely as part of the normal operations of the cell. Transcription factors, proteins that help regulate protein synthesis, are targets of such degradations. Their degradation is not a significant contributor to the energy needs of the cell. [3]
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).
[6] [7] [8] VIP stimulates contractility in the heart, causes vasodilation, increases glycogenolysis, lowers arterial blood pressure and relaxes the smooth muscle of trachea, stomach and gallbladder. In humans, the vasoactive intestinal peptide is encoded by the VIP gene. [9] VIP has a half-life (t ½) in the blood of about two minutes. [10]