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The insulin transduction pathway is an important biochemical pathway beginning at the cellular level affecting homeostasis. This pathway is also influenced by fed versus fasting states, stress levels, and a variety of other hormones. When carbohydrates are consumed, digested, and absorbed the pancreas senses the subsequent rise in blood glucose concentration and releases insulin to promote an uptake of glucose from the blood stream. When insulin binds on the cellular insulin receptor, it leads to a cascade of cellular processes that promote the usage or, in some cases, the storage of glucose in the cell. The effects of insulin vary depending on the tissue involved, e.g., insulin is most important in the uptake of glucose by muscle and adipose tissue. This insulin signal transduction pathway is composed of trigger mechanisms (e.g., autophosphorylation mechanisms) that serve as signals throughout the cell. There is also a counter mechanism in the body to stop the secretion of insulin beyond a certain limit. Namely, those counter-regulatory mechanisms are glucagon and epinephrine. The process of the regulation of blood glucose (also known as glucose homeostasis) also exhibits oscillatory behavior. On a pathological basis, this topic is crucial to understanding certain disorders in the body such as diabetes (type 1,2,3), hyperglycemia and hypoglycemia. ==Insulin signal transduction pathway== The functioning of a signal transduction pathway is based on extra-cellular signaling that in turn creates a response which causes other subsequent responses, hence creating a chain reaction, or cascade. During the course of signaling, the cell uses each response for accomplishing some kind of a purpose along the way. Insulin secretion mechanism is a common example of signal transduction pathway mechanism. Insulin is produced by the pancreas in a region called Islets of Langerhans. In the islets of Langerhans, there are beta-cells, which are responsible for production of insulin. Insulin is secreted as a response mechanism for counteracting the increasing excess amounts of glucose in the blood. Glucose in the body increases after food consumption. This is primarily due to carbohydrate intake, but to much lesser degree protein intake (())(()). Depending on the tissue type, the glucose enters the cell through facilitated or passive diffusion. In muscle and adipose tissue, glucose enters through GLUT 4 receptors via facilitated diffusion (()). In brain, kidney and retina, glucose enters passively. In the beta-cells of the pancreas, glucose enters through the GLUT 2 receptors (process described below). Two aspects of this process are explained below: insulin secretion and insulin action on the cell. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Insulin signal transduction pathway and regulation of blood glucose」の詳細全文を読む スポンサード リンク
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