Pancreas

The pancreas has dual functions: an exocrine component and an endocrine component. The exocrine pancreas comprises approximately 95% of the gland's mass and consists of acinar cells that produce digestive enzymes—including lipase, amylase, and trypsinogen—which are secreted into the duodenum via the pancreatic duct. The endocrine pancreas consists of scattered clusters of cells called islets of Langerhans that secrete hormones directly into the bloodstream.

The islets of Langerhans contain several cell types: beta cells produce insulin, which lowers blood glucose by promoting cellular uptake and glycogen storage; alpha cells produce glucagon, which raises blood glucose by stimulating glycogenolysis and gluconeogenesis in the liver; and delta cells produce somatostatin, which inhibits both insulin and glucagon secretion and slows digestive processes.

In Type 1 diabetes mellitus, the immune system destroys the pancreatic beta cells, resulting in near-total loss of insulin production. Patients require exogenous insulin to survive. In Type 2 diabetes mellitus, beta cells continue to produce insulin, but peripheral tissues develop resistance to its effects; eventually, beta cell exhaustion may occur. Type 2 is primarily managed with lifestyle changes, oral medications, and sometimes insulin.

Acute pancreatitis is most commonly caused by gallstones obstructing the pancreatic duct or by excessive alcohol consumption. When digestive enzymes such as trypsinogen are activated prematurely within the pancreatic tissue rather than the duodenum, they begin digesting the pancreas itself—a process called autodigestion. This triggers severe inflammation, pain, and can lead to pancreatic necrosis, infection, and systemic inflammatory response syndrome.

Pancreatic cancer is often diagnosed at an advanced stage because the pancreas is located deep in the retroperitoneum with few early symptoms, and there are no reliable screening tests for the general population. By the time symptoms such as jaundice, weight loss, or back pain appear, the tumor has typically spread to local vessels or distant organs. The five-year survival rate is approximately 11-12% for all stages combined.