The pancreas is a large, elongated, grayish pink racemose gland organ located behind the stomach between the liver, kidneys, spleen and duodenum. It is composed of the exocrine and endocrine tissues being a dual function gland. The endocrine function of the pancreas is served by the Islets of Langerhans, a lightly staining cluster of cells while the exocrine function is served by the pancreatic acini, the darker staining cells that are connected to the gut through a system of ducts that runs the length of the organ, draining to smaller ducts and emptying into the duodenum at the major duodenal papilla, the same site that accommodates the entrance of the common bile duct.
The Islets of Langerhans is made of numerous cell clusters composed of four main cell types. These cells secrete specific hormones. The beta cells secrete insulin which acts on the metabolism of carbohydrates, alpha cells secrete glucagons ( a hormone that elevates blood sugar), delta cells secrete somatostatin which regulates the alpha and beta cells and is believed to control metabolic processes, and pp cells secrete pancreatic polypeptide. The cells of the Islets of Langerhans intersect with capillaries which are lined by endocrine cells which are in direct contact with blood vessels and are so focused in the manufacture of hormones.
The pancreatic acini secretes pancreatic juice containing digestive enzymes into the duodenum to help in the digestion of protein, carbohydrates and fats. Bicarbonate ions in the pancreatic juice neutralize the acidic chyme coming from stomach to the duodenum.
The automatic nervous system regulates the pancreas through hormones secreted in the blood.