Which hormone activates glycogenolysis and gluconeogenesis?

• A. Insulin
• B. Glucagon
• C. Cortisol
• D. Epinephrine

Answer: (B)

Glycogenolysis and gluconeogenesis are key processes in glucose metabolism that serve to increase blood glucose levels, particularly during fasting or intense exercise. The hormone that primarily initiates and regulates these processes is glucagon.

Glucagon, produced by the alpha cells of the pancreas, is released in response to low blood glucose levels. It activates glycogenolysis, which is the breakdown of glycogen into glucose, allowing the body to utilize stored glucose for energy. Additionally, glucagon stimulates gluconeogenesis, the process by which glucose is synthesized from non-carbohydrate sources, such as amino acids and glycerol, particularly in the liver. This hormonal action is critical in maintaining adequate blood glucose levels during periods of low carbohydrate intake or increased metabolic demand.

While insulin, cortisol, and epinephrine influence glucose metabolism, they do so in different ways. Insulin primarily facilitates glucose uptake and storage rather than promoting glucose release. Cortisol contributes to gluconeogenesis but also has a broader role in metabolism and counterregulatory functions during stress. Epinephrine, while promoting glycogenolysis in muscle cells and contributing to the "fight or flight" response, is more of an acute response mechanism rather than a primary regulator of glucose levels