Pancreas Function: Digestive Enzymes and Hormonal Regulation

The pancreas is a dual‑function gland: exocrine (digestive) and endocrine (hormonal).

Exocrine Function (95% of mass)

• Secretes 1.5–3 L/day of pancreatic juice into duodenum via main pancreatic duct (Wirsung).
• Enzymes:
  • Amylase → carbohydrates (starch → maltose)
  • Lipase → fats (triglycerides → fatty acids + monoglycerides) — requires bile for emulsification
  • Proteases (trypsinogen, chymotrypsinogen) → proteins (activated in duodenum by enterokinase)
  • Nucleases → DNA/RNA
• Bicarbonate: Neutralizes acidic chyme (pH 2→7–8) for enzyme function.

Endocrine Function (Islets of Langerhans, 1–2% of mass)

• β‑cells (65–80%): Insulin → lowers blood glucose (promotes uptake, storage).
• α‑cells (15–20%): Glucagon → raises blood glucose (glycogenolysis, gluconeogenesis).
• δ‑cells: Somatostatin → inhibits insulin/glucagon/GH.
• PP‑cells: Pancreatic polypeptide → regulates exocrine secretion, appetite.

Clinical Relevance

• Diabetes: β‑cell failure (T1 autoimmune; T2 insulin resistance + relative deficiency).
• Pancreatitis: Premature enzyme activation → autodigestion; lipase/amylase elevated.
• Cystic fibrosis: Thick mucus blocks ducts → exocrine insufficiency.
• Pancreatic cancer: Often exocrine (adenocarcinoma); late presentation.

The pancreas is a metabolic hub—digesting your lunch while regulating your blood sugar in real time.