What is one of the effects of glucagon on the liver?

• A. Inhibits gluconeogenesis
• B. Stimulates glucose storage
• C. Stimulates glycogen breakdown
• D. Decreases glucose output

Answer: (C)

Glucagon plays a key role in maintaining glucose homeostasis in the body, particularly when blood glucose levels are low. One of its primary functions is to stimulate glycogen breakdown, a process known as glycogenolysis. When glucagon is released, particularly during fasting or low carbohydrate intake, it binds to receptors on liver cells (hepatocytes) and activates signaling pathways that lead to the conversion of glycogen, the stored form of glucose, back into glucose molecules. This glucose is then released into the bloodstream to elevate blood sugar levels and provide energy for bodily functions.

This process is crucial during times of glucose deficiency, allowing the liver to release glucose directly into circulation where it can be used by other tissues, such as muscle and brain cells. By stimulating glycogen breakdown, glucagon helps ensure that the body maintains adequate glucose levels, which is vital for normal physiological function.

In contrast, options that suggest inhibition of gluconeogenesis or stimulation of glucose storage do not align with glucagon’s primary role, as glucagon promotes gluconeogenesis (the production of glucose from non-carbohydrate sources) and enhances the availability of glucose rather than storing it. The option indicating a decrease in glucose output contradicts the function of glucagon, which