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insulin
(inīsә-lin)
the major fuel-regulating hormone of the body, formed from proinsulin in the beta cells of the islets of Langerhans in the pancreas. Insulin promotes the storage of glucose and the uptake of amino acids, increases protein and lipid synthesis, and inhibits fat breakdown and gluconeogenesis. Secretion of insulin is a response of the beta cells to a stimulus; the primary stimulus is the presence of glucose, and others are amino acids and certain hormones. After insulin is released from the beta cells, it enters the bloodstream and is transported to cells throughout the body. The cell membranes have insulin receptors to which the hormone becomes bonded or “fixed.” An interaction between the insulin and its receptors leads to biochemical
processes that include: transport of glucose, amino acids, and certain ions into the cell body; storage of glycogen in liver and muscle cells; synthesis of triglyceridesand storage of fat; synthesis of protein, RNA, and DNA; and inhibition of gluconeogenesis, and breakdown of glycogen, protein, and fats.
a preparation of the hormone used in treatment of diabetes mellitus; it may be prepared from the pancreas of an animal, be created by recombinant technology, or be an insuline analogue that has a small chemical alteration.
Copyright 2007. An Elsevier publication. All rights reserved.
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