Question

List the hormones secreted by G-I tract.

Answer 1

Both the stomach and the small intestine of the gastrointestinal tract produce hormones.

Hormones produced by the stomach

The 'G' cells of the stomach secrete the hormone called gastrin.

• The stimuli for gastrin production include; ingestion of meal, distention (swelling/enlargement) of stomach and products of protein digestion.
• It has 2 main functions; stimulation of gastric acid secretion and stimulation of growth of the gastric mucosa.

Hormones produced by the small intestine

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

GIP

• Stimulates release of insulin from pancreas
• Inhibits gastric acid secretion

Motilin

• It is involved in the motility of the gastrointestinal tract.