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GIT HORMONES. DR. AMEL EASSAWI Dr. Shaikh Mujeeb Ahmed. OVERVIEW OF GASTRO-INTESTINAL HORMONES. We will discuss the following hormones: Gastrin Secretin CCK Motilin Somatostatin GIP VIP. GASTRIN. Produced by G-cells in the stomach. Functions:
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GIT HORMONES DR. AMEL EASSAWI Dr. Shaikh Mujeeb Ahmed
OVERVIEW OF GASTRO-INTESTINAL HORMONES We will discuss the following hormones: • Gastrin • Secretin • CCK • Motilin • Somatostatin • GIP • VIP
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].
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.
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.
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.
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.
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].
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.
References • Human physiology by Lauralee Sherwood, seventh edition • Text book physiology by Guyton &Hall,11th edition • Text book of physiology by Linda .s contanzo,third edition