Gastrointestinal hormones

Below is a brief summary of the major hormones involved in food digestion:

_ Source _ Stimulus _ Actions| Gastrin _G cells in antrum of the stomach _Distension of stomach, vagus nerves (mediated by gastrin-releasing peptide), luminal peptides/amino acids Inhibited by: low antral pH, somatostatin _Increases acid secretion by gastric parietal cells, pepsinogen and IF secretion, increases gastric motility, stimulates parietal cell maturation| CCK _I cells in upper small intestine _Partially digested proteins and triglycerides _Increases secretion of enzyme-rich fluid from pancreas, contraction of gallbladder and relaxation of sphincter of Oddi, decreases gastric emptying, trophic effect on pancreatic acinar cells, induces satiety| Secretin _S cells in upper small intestine _Acidic chyme, fatty acids _Increases secretion of bicarbonate-rich fluid from pancreas and hepatic duct cells, decreases gastric acid secretion, trophic effect on pancreatic acinar cells| VIP _Small intestine, pancreas _Neural _Stimulates secretion by pancreas and intestines, inhibits acid secretion| Somatostatin _D cells in the pancreas & stomach _Fat, bile salts and glucose in the intestinal lumen _Decreases acid and pepsin secretion, decreases gastrin secretion, decreases pancreatic enzyme secretion, decreases insulin and glucagon secretion inhibits trophic effects of gastrin, stimulates gastric mucous production|