Question

Cholecystokinin and secretin are

• A. Hormones liberated by mucosa of duodenum which stimulate gallbladder and pancreas respectively
• B. Hormones liberated by mucosa of duodenum which stimulate the adrenal cortex
  
• C. Hormones liberated by mucosa of duodenum which stimulate the adrenal medulla
  
• D. Enzymes that are involved in the digestion of cholesterol and saccharides.

Answer 1

The correct option is A Hormones liberated by mucosa of duodenum which stimulate gallbladder and pancreas respectively

The small intestine secretes 4 hormones; cholecystokinin, secretin, gastric inhibitory peptide (GIP) and Motilin.

• While Cholecystokinin and secretin are secreted by all the three parts of the small intestine (duodenum, jejunum, and ileum), GIP and motilin is secreted by only duodenum and jejunum.
• Cholecystokinin is produced by the 'I' cells, 'S' cells produce secretin, GIP is formed by the 'K' cells and the 'M' cells secrete motilin
• These hormones are secreted as a result of various stimuli like protein, fat, carbohydrate and acid in the intestine.

Cholecystokinin

• Stimulates pancreatic enzyme and bicarbonate secretion
• Stimulates contraction of the gallbladder
• Also stimulates the growth of the exocrine pancreas
• It inhibits gastric emptying (entry of food into intestine by emptying stomach)

Secretin

• It stimulates pepsin secretion from stomach and bicarbonate secretion from both pancreas and gallbladder
• Also promotes the growth of exocrine pancreas.
• It inhibits gastric acid secretion.