Describe how the body maintains control of blood glucose

If the concentration of glucose in the blood is too high, this is detected by beta cells in the pancreatic islets, which release the hormone insulin. Insulin has several actions in the body: firstly, it increases the uptake of glucose into cells. Secondly, it stimulates the liver cells to make glycogen (glycogenesis) - glycogen is a glucose polysaccharide which allows glucose to be stored in the body. Insulin therefore lowers the concentration of glucose in the blood. If the concentration of glucose goes too low, this is detected by alpha cells in the pancreatic islets, which release the hormone glucagon. Glucagon also has several actions: firstly, it increases the breakdown of glycogen in the liver back into glucose (glycogenolysis). Secondly, it increases the production of new glucose (gluconeogenesis). Therefore glucagon increases the concentration of glucose in the blood. In this way, the body can maintain the concentration of blood glucose in a normal range (homeostasis).