Function of the Pancreas

The pancreas is an elongated glandular organ of the digestive system that regulates blood glucose levels. It is located in the upper left portion of the abdomen between the stomach and the small intestine. It is both a digestive and an endocrine organ, and so it is considered a "mixed gland." As its digestive function, it secretes pancreatic juice, which neutralizes the acidic chyme (fluid) as it moves from the stomach to the intestines. The pancreas also secretes digestive enzymes that travel through the pancreatic canal and enter the small intestine. There the enzymes aid in digestion of food in the small intestine. One such enzyme is trypsin, which aids in protein digestion.

In addition to this digestive function, the pancreas also contains specialized hormone-producing tissues. These tissues are arranged into the islets of Langerhans. An islet of Langerhans is a specialized cluster of endocrine cells located along the length of the pancreas that produces the hormones glucagon and insulin. There are nearly three million of these cell clusters distributed along the length of the pancreas. The clusters are crossed by a dense network of capillaries so that the hormones secreted by cells in the islets can enter the bloodstream rapidly.

Islets of Langerhans contain two main types of cells: alpha cells and beta cells. Alpha cells produce the hormone glucagon and beta cells produce the hormone insulin, and together, glucagon and insulin regulate blood glucose levels. The pancreas responds to a decrease in blood glucose levels by secreting glucagon. Glucagon is a pancreatic hormone that increases blood sugar by triggering glycogen breakdown in the liver. The pancreas responds to an increase in blood glucose levels by secreting insulin, a pancreatic hormone that decreases blood sugar by increasing the rate of glucose uptake in cells throughout the body. Insulin acts on nearly every cell in the body, causing it to increase the rate of glucose uptake. Insulin also increases the production of glycogen from glucose in skeletal muscles and in the liver. Through these processes, insulin lowers blood glucose levels.