The Pancreas
The pancreas is located in the retroperitoneum weighs 70-120g, and is 12-20 cm in length. The head of the pancreas lies in the C loop of the duodenum, while its tail lies behind the stomach and points towards the spleen.
Exocrine functions
The pancreas is comprised of 95% acinar cells and 1-2% islet cells. Acinar cells form exocrine glands, producing proteolytic enzymes which are released into pancreatic ducts and flow into the duodenum through the amuplla of Vater. Acinar cells also secrete protective enzymes such as pro-colipase and trypsin inhibitor. Acinal cell secretion is controlled by CCK. Lipase, amylase, and ribonuclease are all secreted in active form, while proteolytic enzymes are inactive until converted by trypsin.
Ductal cells secrete water, electrolytes, and bicarbonate, decreasing secretion viscosity and alkalinizing (3.5-4) the intestinal environment to enhance enzyme activity. 1-2 lites of fluid are secreted into the small intestine daily. Duct cell secretion is controlled by secretin.
Endocrine functions
The pancreas is composed of 1-2% islet cells. These produce important hormones such as insulin, glucagon, somatostatin, and pancreatic polypeptide.