GI Hormones

Question 1

Gastrin (Family: Gastrin-CCK)

Answer 1

• Site of secretion
  G cells of the stomach
• Stimuli for secretion
  Small peptides and amino acids
  Distention of the stomach
  Vagal stimulation (GRP)
• Action
  ↑ Gastric H+ secretion
  Stimulates growth of gastric mucosa

Question 2

Cholecystokinin (CCK) (Family: Gastrin-CCK)

Answer 2

• Site of secretion
  I cells of the duodenum and jejunum
• Stimuli for secretion
  Small peptides and amino acids
  Fatty acids
• Actions
  ↑ Pancreatic enzyme secretion
  ↑ Pancreatic HCO3- secretion
  Stimulates contraction of the gallbladder and relaxation of the sphincter of Oddi
  Stimulates growth of the exocrine pancreas and gallbladder
  Inhibits gastric emptying

Question 3

Secretin (Family: Secretin-glucagon)

Answer 3

• Site of secretion
  S cells of the duodenum
• Stimuli for secretion
  H+ in the duodenum
  Fatty acids in the duodenum

- Actions
↑ Pancreatic HCO3- secretion
↑ Biliary HCO3- secretion 
↓ Gastric H+ secretion
Inhibits trophic effect of gastrin on gastric mucosa

Question 4

Glucose- Dependent Insulinotropic Peptide (GIP) (Family: Secretin-glucagon)

Answer 4

• Site of secretion
  Duodenum and jejunum
• Stimuli for secretion
  Fatty acids
  Amino acids
  Oral glucose
• Actions
  ↑ Insulin secretion from pancreatic β cells
  ↓ Gastric H+ secretion