1. GIT HORMONES DR. AMEL EASSAWI DR. SHAIKH MUJEEB AHMED 1

2. OVERVIEW OF GASTRO- INTESTINAL HORMONES We will discuss the following hormones: -Gastrin -Secretin -CCK -Motilin -Somatostatin -GIP -VIP 2

3. GASTRIN Produced by G-cells in the stomach.Functions: Stimulates the release of HCL and Pepsinogen in the stomach. Increases gastric motility. Increases ileal motility. Relaxes Ileocecal Sphincter. Induces mass movements in colon [help the contents moving through GIT on arrival of new meal in the stomach]. 3

4. SECRETIN Secretin is released from small intestine when stomach acid contents come to duodenum. Functions: It inhibits gastric emptying to delay the acid contents of stomach to enter in the duodenum. It inhibits gastric secretion. It acts on pancreatic duct to produce large volume of watery, NaHCO3 secretion. It stimulates the secretion of NaHCO3 rich bile in the liver by acting on the bile ducts. 4

5. CCK (Cholecystokinin) CCK is released from the duodenum in response mainly to fat, to a lesser extent to protein products.Functions: Inhibition of motility and secretion Stimulates pancreatic Acinar cells to secrete pancreatic enzymes [amylase, lipase, Trypsinogen, Chymotrypsinogen]. Causes contraction of gall-bladder and relaxation of sphincter of Oddi. 5

6. MOTILIN It is polypeptide and secreted by Entrochromaffin cells and M cells in the stomach, small intestine and colon.Functions: Causes contraction of smooth muscles in the stomach and intestine. Increases during inter-digestive state and controls GIT motility between the meals. 6

7. SOMATOSTATIN Secreted by D-Cells in pancreatic islets and by similar D-cells in GIT mucosa.Functions: Inhibits secretion of Gastrin, VIP, GIP, Secretin and Motilin. Somatostatin secretion is stimulated by acid in the lumen of intestine. It acts in a paracrine fashion. 7

8. GIP [Glucose Dependent Insulinotorphic Peptide] GIP is released from the duodenum.Functions: GIP causes release of insulin. Insulin causes uptake and storage of glucose. GIP – before it was called Gastric Inhibitory Peptide [this role is minimum]. 8

9. VIP [Vasoactive Intestinal Peptide] VIP is found in nerves in the GIT. VIP is also found in the brain, blood, autonomic nerves.Functions: It stimulates intestinal secretion of electrolytes and water. Relaxation of intestinal smooth muscle including sphincters. Inhibition of gastric acid secretion. It potentiates the action of acetylcholine in salivary glands. 9

10. REFERENCES Human physiology by Lauralee Sherwood, seventh edition Text book physiology by Guyton &Hall,11 th edition Text book of physiology by Linda.s contanzo,third edition 10