Friday, September 3, 2010

Insulin

Insulin is a hormone that regulates the body's use of sugar and other food. It is produced in specialized cells in the islets of Langerhans, a part of the pancreas. Certain insulin-related abnormalities cause the disease diabetes mellitus, often simply called diabetes. In this disease, the body cannot use sugars properly and glucose (a form of sugar) builds up in the blood. Insulin also affects the body's use of protein, fat, and mineral products, such as potassium and phosphate.

How insulin acts in the body
When food is absorbed into the bloodstream, the pancreas increases the secretion of insulin into the blood. Insulin speeds the movement of nutrients from the bloodstream into target cells located mainly in liver, muscle, and fat tissues. Specialized protein molecules called insulin receptors lie on the surface of the target cells. The insulin receptors bind to insulin, which activates the receptors. The activated receptors on cells hasten the entry and utilization of the nutrients. Glucose and other simple sugars, produced by the digestion of more complex carbohydrates, are used for immediate energy or converted to glycogen for storage. Amino acids, produced by the digestion of proteins, move into cells and there form the building blocks for proteins. Fatty acids, produced by the digestion of fats, are converted to tryglycerides for storage and later used for energy.

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