Pancreas

Definition

The pancreas is an organ important in digestion and blood sugar regulation. It is considered to be part of the gastrointestinal system. The pancreas produces digestive enzymes to be released into the small intestine to aid in reducing food particles to basic elements that can be absorbed by the intestine and used by the body. It has another very different function in that it forms insulin, glucagon and other hormones to be sent into the bloodstream to regulate blood sugar levels and other activities throughout the body.

Description

The pancreas is a pear-shaped organ about 6 in (15 cm) long located in the middle and back portion of the abdomen. It is connected to the first part of the small intestine, the duodenum, and lies behind the stomach. The pancreas is made up of glandular tissue, or cells that form substances to be secreted outside of the organ. Glandular tissues can be categorized as endocrine (secreting directly into the bloodstream or lymph) or exocrine (secreting into another organ). The pancreas is both an exocrine and an endocrine organ.

Exocrine secretions

The digestive juices produced by the pancreas are secreted into the duodenum via a Y-shaped duct, at the point where the common bile duct from the liver and the pancreatic duct join just before entering the duodenum. In this way, a variety of digestive enzymes (trypsin, chymotrypsin, lipase, and amylase, among others) are delivered into the small intestine to aid in the digestion of proteins, fats, and carbohydrates. The enzymes are delivered in an inactive form called zymogens. The zymogens are activated by the chemical substances in the small intestine. The digestive enzymes carried into the duodenum are representative of the exocrine function of the pancreas, in which specific substances are made to be passed directly into another organ.

Endocrine secretions

The pancreas is unusual among the body's glands in that it also has a very important endocrine function. Small groups of special cells called islet cells throughout the organ make such hormones as insulin and glucagon, which are critical in regulating blood sugar levels; and vasoactive intestinal peptide, which influences gastrointestinal activity. These hormones are secreted directly into the bloodstream to affect organs all over the body. No organ except the pancreas makes significant amounts of insulin or glucagon, but other tissues do produce vasoactive intestinal peptide. Insulin acts to lower blood sugar levels by allowing the sugar to flow into cells. Glucagon acts to raise blood sugar levels by causing glucose to be released into the circulation from its storage sites. Insulin and glucagon act in an opposite but balanced fashion to keep blood sugar levels stable.