Pancreas

Function

The pancreas is two glands in one. Its exocrine acini — 99% of its mass — pour 1.5 L of enzyme-rich juice daily into the duodenum: amylase, lipase, trypsinogen and bicarbonate, the latter neutralising gastric acid via ductal cells. Trypsinogen activates only in the duodenal lumen, a fail-safe against self-digestion.

Scattered among the acini, a million pancreatic islets (1–2% of mass) run the endocrine program: beta cells secrete insulin to store glucose, alpha cells glucagon to mobilise it, delta cells somatostatin to pace the whole. The pancreas' retroperitoneal hideaway behind the stomach is why pancreatic pain bores through to the back.

Blood supply

Splenic artery (tail and body), gastroduodenal and inferior pancreaticoduodenal arteries.

Nerve supply

Vagal parasympathetic stimulates enzyme secretion; sympathetic from the coeliac and superior mesenteric plexuses; visceral pain referred to the back and left scapula.

Clinical relevance

Acute pancreatitis

Gallstones or alcohol release activated enzymes into the gland's own substance — a chemical burn from within; CT shows a swollen gland with peripancreatic fat stranding or fluid.

Type 1 diabetes

Autoimmune destruction of beta cells ends insulin production — exogenous insulin becomes life's daily contract.

Pancreatic cancer

Tumours of the head obstruct the common bile duct, causing painless jaundice; those of the body and tail present late.

Related conditions

• Cystic fibrosis
• Acute pancreatitis
• Chronic pancreatitis
• Pancreatic cancer
• Type 2 diabetes
• Type 1 diabetes