The pancreatic hormones glucagon and insulin regulate blood glucose levels. Between meals or during fasting, the blood glucose levels drop, triggering the pancreatic alpha cells to release glucagon. Glucagon's primary function is to promote the synthesis and release of glucose, consequently increasing the amount of blood glucose. In the liver and skeletal muscles, glucagon stimulates glycogenolysis, which converts glycogen to glucose. It also stimulates the conversion of carbon-containing compounds, such as lactic acid and amino acids, into glucose through gluconeogenesis. Right after meals, the blood glucose levels surge, triggering the pancreatic beta cells to release insulin. Insulin binds its receptors on the target cell membrane and promotes glucose uptake and metabolism. After glucose enters the cells, insulin further stimulates glycolysis, accelerating the rate of glucose breakdown and ATP production. It also promotes protein synthesis, glycogen synthesis, and conversion of glucose to fat to prevent excess blood glucose levels.