Final answer:
Glucagon is a hormone secreted by the pancreas that helps regulate blood glucose levels by promoting glycogenolysis, gluconeogenesis, and lipolysis.
Step-by-step explanation:
Glucagon is a peptide hormone secreted by the alpha cells of the pancreas. It is also known as the hyperglycemic-glycogenolytic factor (HGF) and plays a crucial role in maintaining blood glucose homeostasis. When blood glucose levels fall below normal, glucagon is released to stimulate the breakdown of glycogen in the liver (glycogenolysis) and stimulate gluconeogenesis, the synthesis of glucose from non-carbohydrate sources like amino acids. Glucagon also promotes lipolysis, the breakdown of fats, and the release of fatty acids into the bloodstream.