(See also Overview of the Digestive System.)
The pancreas is an organ that contains two types of glandular tissue:
The acini produce digestive enzymes. The islets produce hormones. The pancreas secretes digestive enzymes into the duodenum and hormones into the bloodstream.
The digestive enzymes (such as amylase, lipase, and trypsin) are released from the cells of the acini and flow into the pancreatic duct. The pancreatic duct joins the common bile duct at the sphincter of Oddi, where both flow into the duodenum. The enzymes are normally secreted in an inactive form. They are activated only when they reach the digestive tract. Amylase digests carbohydrates, lipase digests fats, and trypsin digests proteins. The pancreas also secretes large amounts of sodium bicarbonate, which protects the duodenum by neutralizing the acid that comes from the stomach.
The three hormones produced by the pancreas are
Insulin lowers the level of sugar (glucose) in the blood by moving sugar into cells. Glucagon raises the level of sugar in the blood by stimulating the liver to release its stores. Somatostatin prevents the other two hormones from being released.