Pancreas and Its Hormonal Functions

The Pancreas

• Location: An elongated, spongy gland situated behind the stomach.
• Function: Primarily an exocrine digestive gland.
• Endocrine Cell Clusters: Known as pancreatic islets (islets of Langerhans) contain:
  • 20% Alpha (α) cells
  • 70% Beta (β) cells
  • 5% Delta (δ) cells
  • Small numbers of PP and G cells.

Hormonal Functions of Pancreatic Cells

Alpha Cells

• Hormone: Secrete glucagon.
• Function:
  • Triggered when blood glucose levels drop, stimulating:
  • Gluconeogenesis
  • Glycogenolysis
  • Release of glucose into circulation
  • Stimulates fat catabolism in adipose tissue, leading to the release of free fatty acids.
• Response: Promotes amino acid absorption, especially post high protein meals.

Beta Cells

• Hormone: Secrete insulin.
• Function:
  • Released during/after meals when glucose and amino acids rise.
  • Stimulates cells for nutrient absorption and promotes glycogen, fat, and protein synthesis.
  • Antagonizes glucagon effects, suppressing the usage of stored food.

Delta Cells

• Hormone: Secret growth hormone-inhibiting hormone (somatostatin).
• Function:
  • Released alongside insulin by beta cells.
  • Inhibits certain digestive enzyme secretion and nutrient absorption.
  • Acts locally to modulate activity of other islet cells.

PP and G Cells

• PP Cells: Secrete pancreatic polypeptide.
  • Function: Inhibit gallbladder contraction and pancreatic digestive enzyme secretion.
• G Cells: Secrete gastrin.
  • Function: Stimulate stomach’s acid secretion, motility, and emptying.
  • Gastrin is also secreted by the small intestine and stomach.