Final answer:
Glucagon is released from the alpha cells of the pancreas when blood glucose levels decline. It raises blood glucose levels through various mechanisms and is regulated by negative feedback.
Step-by-step explanation:
glucagon is released from the alpha cells of the pancreas when blood glucose levels decline. It raises blood glucose levels by stimulating glycogenolysis, gluconeogenesis, and the release of fatty acids into the blood. Glucagon release is regulated through a negative feedback mechanism, where rising blood glucose levels inhibit further glucagon production and secretion.