1. GASTRO-INTESTINAL HORMONES
Dr. Zahoor Ali Shaikh
DR. ABDELRAHMAN MUSTAFA
Department of Basic Medical Sciences
Division of Physiology
Faculty of Medicine
Almaarefa Colleges

2. Endocrinal control of GIT
Main hormones:
Gastrin
Secretin
CCK
Motilin
Somatostatin
GIP
VIP

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

4. SECRETIN Site of secretion
Secretin is released from small intestine when stomach acid contents come to duodenum.
Actions
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.

5. CCK [Cholecystokinin]
Site of secretion
from the duodenum in response mainly to fat, to a lesser extent to protein products.
Actions
(i). Inhibition of motility and secretion
(ii). Stimulates pancreatic Acinar cells to secrete pancreatic enzymes [amylase, lipase, Trypsinogen, Chymotrypsinogen].
(iii). It causes contraction of gall-bladder and relaxation of sphincter of Oddi.

6. MOTILIN Site for secretion
It is polypeptide and secreted by entrochromaffin cells and Mo cells in the stomach, small intestine and colon.
Actions
It causes contraction of smooth muscles in the stomach and intestine.
It level increases during inter-digestive state and controls GIT motility between the meals.

7. SOMATOSTATIN Site for secretion
It is secreted by D-Cells in pancreatic islets and by similar D-cells in GIT mucosa.
Actions
Somatostatin inhibits secretion of Gastrin, VIP, GIP, Secretin and Motilin.
Somatostatin secretion is stimulated by acid in the lumen of intestine.
It acts probably in a paracrine fashion.

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

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

10. REMINDER

11. REMINDER

12. 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