Insulin is produced by the beta cells of the islets of Langerhans in the pancreas. Beta cells detect a rise in the blood glucose concentration and secrete insulin into the blood. The secretion of glucagon is inhibited. Almost all body cells except red blood cells have a glycoprotein insulin receptor on their cell surface membrane.Insulin binding to its receptor causes vesicles containing glucose transport channels to fuse with the cell surface membrane, so more channels are present, allowing the entry of more glucose into cells, especially into muscle cells. The rate of respiration increases as does the rate of glycogenesis by the liver. More glucose is also converted to fat.