Stomach Digestive enzyme

the enzymes secreted in stomach called gastric enzymes. stomach plays major role in digestion, both in mechanical sense mixing , crushing food, , in enzymatic sense, digesting it. following enzymes, hormones or compounds produced stomach , respective function:

pepsin main gastric enzyme. produced stomach cells called chief cells in inactive form pepsinogen, zymogen. pepsinogen activated stomach acid active form, pepsin. pepsin breaks down protein in food smaller particles, such peptide fragments , amino acids. protein digestion, therefore, first starts in stomach, unlike carbohydrate , lipids, start digestion in mouth.
hydrochloric acid (hcl): in essence positively charged hydrogen atoms (h+), or in lay-terms stomach acid, , produced cells of stomach called parietal cells. hcl functions denature proteins ingested, destroy bacteria or virus remains in food, , activate pepsinogen pepsin.
intrinsic factor (if): intrinsic factor produced parietal cells of stomach. vitamin b12 (vit. b12) important vitamin requires assistance absorption in terminal ileum. in saliva, haptocorrin secreted salivary glands binds vit. b, creating vit. b12-haptocorrin complex. purpose of complex protect vitamin b12 hydrochloric acid produced in stomach. once stomach content exits stomach duodenum, haptocorrin cleaved pancreatic enzymes, releasing intact vitamin b12. intrinsic factor (if) produced parietal cells binds vitamin b12, creating vit. b12-if complex. complex absorbed @ terminal portion of ileum.
mucin: stomach has priority destroy bacteria , viruses using highly acidic environment has duty protect own lining acid. way stomach achieves secreting mucin , bicarbonate via mucous cells, , having rapid cell turn-over.
gastrin: important hormone produced g cells of stomach. g cells produce gastrin in response stomach stretching occurring after food enters it, , after stomach exposure protein. gastrin endocrine hormone , therefore enters bloodstream , returns stomach stimulates parietal cells produce hydrochloric acid (hcl) , intrinsic factor (if).
gastric lipase: gastric lipase acidic lipase secreted gastric chief cells in fundic mucosa in stomach. has ph optimum of 3–6. gastric lipase, lingual lipase, comprise 2 acidic lipases. these lipases, unlike alkaline lipases (such pancreatic lipase), not require bile acid or colipase optimal enzymatic activity. acidic lipases make 30% of lipid hydrolysis occurring during digestion in human adult, gastric lipase contributing of 2 acidic lipases. in neonates, acidic lipases more important, providing 50% of total lipolytic activity.

of note division of function between cells covering stomach. there 4 types of cells in stomach:

parietal cells: produce hydrochloric acid , intrinsic factor.
gastric chief cells: produce pepsinogen. chief cells found in body of stomach, middle or superior anatomic portion of stomach.
mucous neck , pit cells: produce mucin , bicarbonate create neutral zone protect stomach lining acid or irritants in stomach chyme.
g cells: produce hormone gastrin in response distention of stomach mucosa or protein, , stimulate parietal cells production of secretion. g cells located in antrum of stomach, inferior region of stomach.

secretion previous cells controlled enteric nervous system. distention in stomach or innervation vagus nerve (via parasympathetic division of autonomic nervous system) activates ens, in turn leading release of acetylcholine. once present, acetylcholine activates g cells , parietal cells.