Describe how the hormone glucagon helps a healthy individual to maintain their blood glucose concentration correctly.

When an individual's blood glucose concentration rises above the normal range (approximately 70-100mmol/100cm^3), alpha cells in the Islets of Langerhans in the pancreas detect this change and release glucagon. Glucagon promotes glycogenolysis (the break down of glycogen to glucose) in liver and muscle cells, gluconeogenesis (conversion of fats and amino acids to glucose) in liver cells and increases the use of fats and amino acids in respiration while decreasing the respiration of glucose. In addition to this, glucagon inhibits insulin secretion. As the blood glucose concentration returns to normal, the amount of glucagon secreted is reduced. This whole process is a negative feedback mechanism to maintain homeostasis.