Pancreas

The pancreas is an organ of the digestive system (an exocrine system) and the endocrine system. It is located in the abdomen behind the stomach and functions as a gland. 胰腺是消化系统（外分泌系统）和内分泌系统的一部分，位于胃后方的腹腔内，具有腺体功能。

The exocrine portion synthesizes digestive secretions that are released into the pancreatic duct and flow into the small intestine.

The endocrine portion produces peptide hormones in clusters of cells called islet cells. One type of islet cells produces the hormone insulin, and the other type produces the hormone glucagon. Toward the end of regulating carbohydrate and fat metabolism, the two hormones work in opposition to each other. The insulin reduces the blood glucose level and the glucagon increases it. The intake of food will increase the glucose level in the blood, and the pancreas will release insulin, inducing the cells of the body to take up glucose. The cells will either metabolize the glucose for energy or convert it into a fat or into glycogen. Failure of the insulin delivery system can lead to diabetes mellitus.

In the case of a reduction in blood glucose from fasting or from exercise, the pancreas will release glucagon. The glucagon will activate an enzyme in the liver that breaks down glycogen, releasing glucose into the blood. Glucagon also promotes lipid breakdown, which breaks down fatty acids that can be metabolized for energy. The liver is an important storage location for both glycogen and fatty acids. Skeletal muscles are also important locations for glycogen, which can supply energy for extended active exercise.

Diabetes Mellitus

Diabetes Mellitus is a disease characterized by blood glucose levels that are high and fluctuate greatly with sugar intake. It may be caused by defects in insulin production, or defects in the release of insulin or its reception by target cells.

Lack of properly functioning insulin results in the cells relying more on metabolism of fats as an energy source. This has a number of undesirable results: it leads to high levels of circulating lipids in the blood, including cholesterol, and it can cause fat deposits in the blood vessels. High blood pressure and heart disease may follow, and diabetes is an important cause of heart attacks. Damage to the kidneys is also associated with diabetes. Fortunately, insulin supplements help, and supplies of human insulin are now available from bacteria into which the gene for human insulin have been inserted.