E. S cells in upper small intestine – Explanation

Gastrointestinal hormones

	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 HCL, pepsinogen, and IF secretion; increases gastric motility; trophic effect on gastric mucosa
CCK	I cells in upper small intestine	Partially digested proteins and triglycerides	Increases enzyme-rich fluid from pancreas, contracts gallbladder, relaxes sphincter of Oddi, decreases gastric emptying, trophic effect on pancreatic cells, induces satiety
Secretin	S cells in upper small intestine	Acidic chyme, fatty acids	Increases bicarbonate-rich secretion from pancreas and hepatic duct cells, decreases gastric acid secretion, trophic effect on pancreatic acinar cells
VIP	Small intestine, pancreas	Neural stimulation	Stimulates secretion by pancreas and intestines, inhibits acid secretion
Somatostatin	D cells in pancreas & stomach	Fat, bile salts, and glucose in the intestinal lumen	Decreases acid, pepsin, and gastrin secretion; decreases pancreatic enzyme, insulin, and glucagon secretion; inhibits trophic effects of gastrin, stimulates gastric mucous production

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

Explanation