The Pancreas

The pancreas is shown here with the foreground highly magnified to reveal its inner anatomy. Ninety-nine percent of pancreatic tissue is composed of acinar glands, which secrete an alkaline digestive juice into the duodenum via the pancreatic duct to help digest food. The endocrine areas of the pancreas, known as the islets of Langerhans, are composed of two major types of cell. The alpha cells secrete the hormone glucagon, and the beta cells secrete insulin, into the bloodstream. These hormones work in opposition to control the blood glucose level. Insulin promotes the uptake and usage of glucose in the tissues, particularly skeletal muscle and fat, and reduces glucose production in the liver. Glucagon has an anti-insulin effect in the liver, increasing glucose release. The anatomy of the pancreas also includes: the ampulla of the common bile duct: the pancreatic duct, which carries digestive juice containing enzymes to the duodenum; the acini, the exocrine portions of the pancreas which secrete digestive juice into the pancreas; the splenic arteries which conduct oxygenated blood into the pancreas; and the mesenteric veins, which carry deoxygenated blood containing insulin and glucagon away from the pancreas.