The following points highlight the ten important gastrointestinal hormones that regulates digestive secretion. The hormones are: 1. Gastrin 2. Enterogastrone 3. Secretin 4. Cholecystokinin pancreozymin 5. Duocrmin 6. Enterocrinin 7. Vasoactive Intestinal Peptide 8. Villikinin 9. Somatostatin 10. Pancreatic Polypeptide.
Hormone # 1. Gastrin:
This hormone is secreted by gastrin cells (= G-cells) in the pyloric region of the stomach. It stimulates gastric glands to secrete and release the gastric juice. It also stimulates gastric mobility.
Hormone # 2. Enterogastrone:
(= Gastric Inhibitory Peptide— GIP). It is secreted by the duodenal epithelium. It inhibits gastric secretion and motality. It slows gastric contraction, hence it is also called gastric inhibitory peptide.
Hormone # 3. Secretin:
It was the first hormone to be discovered by scientists. It is secreted by the epithelium of duodenum. It releases bicarbonates in the pancreatic juice. It increases secretion of bile. It decreases gastric secretion and motality.
Hormone # 4. Cholecystokinin pancreozymin (CCK-PZ):
The word cholecystokinin is derived from three roots: Chol meaning bile, cyst meaning bladder and kinin meaning to remove. The word pancreozymin is derived from pancreas and zymin, which means enzyme producer. This hormone is secreted by the epithelium of entire small intestine. It stimulates the gall bladder to release bile and pancreas to secrete and release digestive enzymes in the pancreatic juice.
Hormone # 5. Duocrmin:
It is secreted by the duodenal epithelium and stimulates the Brunner’s glands to release mucus and enzymes into the intestinal juice.
Hormone # 6. Enterocrinin:
It is secreted by the epithelium of entire small intestine. It stimulates the crypts of Lieberkuhn to release enzymes into the intestinal juice.
Hormone # 7. Vasoactive Intestinal Peptide (VIP):
It is secreted by the epithelium of entire small intestine. It dilates peripheral blood vessels of the gut. It also inhibits gastric acid secretion.
Hormone # 8. Villikinin:
It is secreted by the epithelium of entire small intestine. It accelerates movement of villi.
Hormone # 9. Somatostatin (SS):
Somatostatin secreted by the Delta cells of islets of Langerhans of the pancreas inhibits the secretion of glucagon by aplha cells and insulin by beta cells Somatostatin produced by argentaffin cells of gastric and intestinal glands suppresses the release of hormones from the digestive tract.
Hormone # 10. Pancreatic Polypeptide (PP):
It is secreted by the pancreatic polypeptide cells (also ailed PP cells or F-cells) of islets of Langerhans. It inhibits the release of pancreatic juice from the pancreas.