Pancreas

The pancreas is a glandular organ of the digestive system located in the upper abdomen, behind the stomach. It extends horizontally from the duodenum on the right to the spleen on the left and is primarily retroperitoneal, with the tail reaching the splenic area. It comprises a head, neck, body, and tail. The organ receives blood mainly from branches of the splenic and celiac arteries and drains venous blood into the portal venous system. Nerve supply comes from the sympathetic and parasympathetic systems via the celiac and superior mesenteric plexuses.

The pancreas has both exocrine and endocrine functions. The exocrine portion consists of acinar cells that secrete digestive enzymes (including amylase, lipase, and proteases such as trypsinogen and chymotrypsinogen) and ductal cells that release bicarbonate-rich fluid. These secretions form pancreatic juice and drain through a network of ducts. The main pancreatic duct, or duct of Wirsung, runs the length of the gland and typically joins the common bile duct to form the hepatopancreatic ampulla, draining into the duodenum at the major duodenal papilla. An accessory duct (duct of Santorini) may drain at the minor papilla in some individuals.

The endocrine component consists of the islets of Langerhans, which secrete hormones into the bloodstream. Beta cells produce insulin; alpha cells produce glucagon; delta cells secrete somatostatin; and pancreatic polypeptide–producing cells modulate both exocrine and endocrine functions. These hormones regulate glucose metabolism and other aspects of digestion and energy balance.

Clinical relevance includes pancreatitis, pancreatic cancer, and conditions causing exocrine insufficiency (as seen in cystic fibrosis) or diabetes mellitus. Diagnosis and management rely on biochemical tests, imaging, and, when needed, endoscopic procedures.