Glucagons

Glucagon is a peptide hormone produced by the alpha cells of the pancreas. It plays a crucial role in regulating blood glucose levels. Primarily, glucagon acts to increase blood glucose concentration, opposing the action of insulin. When blood glucose levels drop too low, such as during fasting or prolonged exercise, the pancreas releases glucagon.

The main target organ for glucagon is the liver. Upon binding to receptors on liver cells, glucagon stimulates glycogenolysis, the breakdown of stored glycogen into glucose, which is then released into the bloodstream. Glucagon also promotes gluconeogenesis, a process where the liver synthesizes glucose from non-carbohydrate precursors like amino acids and lactate. These combined actions effectively raise blood glucose levels back to a normal range.

The secretion of glucagon is tightly regulated. Low blood glucose is a primary stimulus for its release, while high blood glucose and insulin act to suppress it. Other factors, such as certain amino acids and sympathetic nervous system activity, can also influence glucagon secretion. Glucagon's counter-regulatory role with insulin is essential for maintaining glucose homeostasis, preventing hypoglycemia, and ensuring a steady supply of glucose to the brain and other tissues. Disorders affecting glucagon production or action can contribute to metabolic imbalances.