What effect does glucagon have on the liver?

Glucagon plays a critical role in regulating blood glucose levels, especially during periods of fasting or low carbohydrate intake. When glucagon is released, particularly from the alpha cells of the pancreas, it primarily targets the liver to elevate glucose levels in the bloodstream.

One of the main actions of glucagon is to stimulate gluconeogenesis, which is the process of producing glucose from non-carbohydrate precursors such as amino acids and glycerol. By promoting this pathway, glucagon ensures that the liver generates new glucose molecules that can be released into circulation to maintain adequate blood glucose levels.

Additionally, glucagon stimulates glycogenolysis, which is the breakdown of glycogen (the stored form of glucose) back into glucose. This rapid release of glucose from glycogen stores complements the new glucose produced through gluconeogenesis, enhancing the liver's ability to provide glucose to the body when it's needed.

Together, these actions of stimulating both gluconeogenesis and glycogenolysis highlight glucagon's essential role in mobilizing energy resources during times of fasting or low carbohydrate intake.