What effect does glucagon have on the liver?

• A. Increases glycogen storage
• B. Stimulates gluconeogenesis
• C. Inhibits fat breakdown
• D. Reduces glucose output

Answer: (B)

Glucagon plays a critical role in maintaining blood glucose levels, especially during fasting or low-carbohydrate intake. Its primary effect on the liver is to stimulate gluconeogenesis, which is the metabolic process through which glucose is synthesized from non-carbohydrate substrates. This process typically occurs when blood glucose levels are low, allowing glucagon to signal the liver to generate and release glucose into the bloodstream to ensure that tissues, particularly the brain, have a continuous supply of this essential energy source.

By promoting gluconeogenesis, glucagon helps to counteract the effects of insulin, which drives glucose uptake and storage within the liver and other tissues. Hence, when glucagon is elevated, it effectively increases the production of glucose, thereby raising blood sugar levels to maintain homeostasis. This mechanism is vital for survival during periods of fasting or intense physical activity.