the release of the protein insulin from pancreatic cells occurs by
Insulin signal transduction pathway Glucose gets converted to Glucose-6-Phosphate (G6P) through Glucokinase; and G6P is subsequently oxidized to form ATP. This process inhibits the ATP-sensitive potassium ion channels of the cell causing the Potassium ion channel to close and not function anymore. The closure of the ATP-sensitive potassium channels causes depolarization of the cell membrane causing the cell membrane to stretch which causes the voltage-gated calcium channel on the membrane to open causing an influx of Ca2+ ions. This influx then stimulates fusion of the insulin vesicles to the cell membrane and secretion of insulin in the extracellular fluid outside the beta cell; thus making it enter the bloodstream. [Also Illustrated in Figure 1.1.1].[2]
Glycogen After a meal has been digested and glucose levels begin to fall, insulin secretion is reduced, and glycogen synthesis stops. When it is needed for energy, glycogen is broken down and converted again to glucose. Glycogen phosphorylase is the primary enzyme of glycogen breakdown. For the next 8â€“12 hours, glucose derived from liver glycogen is the primary source of blood glucose used by the rest of the body for fuel.