The pancreas is a lobulated organ lying on the posterior abdominal wall behind the peritoneum. Its head lies within the concavity of the duodenum, the body extends across the midline and the tail abuts the spleen. The main pancreatic duct joins the common bile duct to enter the duodenum as a single duct at the Ampulla of Vater. Most (98%) of the pancreas is exocrine glandular tissue. In response to cholecystokinin and secretin the pancreas secretes lipases, amylases and proteases for digestion. Endocrine cells lie in the islets of Langerhans which do not connect with the duct system. Within the islets there are four cell types. b cells secrete insulin, a cells secrete glucagon, D cells secrete somatostatin and PP cells secrete pancreatic polypeptide.
