What physiological effect does glucagon signaling primarily have in the liver?

What physiological effect does glucagon signaling primarily have in the liver?

• A. Increases glycogen synthesis
• B. Promotes glycogenolysis and gluconeogenesis
• C. Inhibits protein synthesis
• D. Stimulates fatty acid storage

Answer: (B)

Glucagon signaling primarily promotes glycogenolysis and gluconeogenesis in the liver, which are crucial physiological processes that help to increase blood glucose levels, especially during fasting or low-energy states. When glucagon is released from the pancreas in response to low blood glucose concentrations, it binds to its receptor on liver cells, activating a cascade of intracellular signaling pathways primarily through the cAMP second messenger system. This signaling leads to the activation of enzymes responsible for glycogenolysis, the breakdown of glycogen into glucose, which is then released into the bloodstream. At the same time, glucagon stimulates gluconeogenesis, the process by which the liver generates new glucose from non-carbohydrate precursors, such as amino acids and glycerol. Together, these processes ensure that the body maintains adequate glucose levels necessary for energy, particularly for vital organs like the brain. In contrast, the other options reflect physiological processes that are not the primary role of glucagon. For example, increasing glycogen synthesis is a response to insulin signaling, not glucagon, which is antagonistic to this process. Inhibiting protein synthesis and stimulating fatty acid storage are not direct effects of glucagon; instead, glucagon's primary function is to mobilize glucose stores to provide

Glucagon signaling primarily promotes glycogenolysis and gluconeogenesis in the liver, which are crucial physiological processes that help to increase blood glucose levels, especially during fasting or low-energy states. When glucagon is released from the pancreas in response to low blood glucose concentrations, it binds to its receptor on liver cells, activating a cascade of intracellular signaling pathways primarily through the cAMP second messenger system.

This signaling leads to the activation of enzymes responsible for glycogenolysis, the breakdown of glycogen into glucose, which is then released into the bloodstream. At the same time, glucagon stimulates gluconeogenesis, the process by which the liver generates new glucose from non-carbohydrate precursors, such as amino acids and glycerol. Together, these processes ensure that the body maintains adequate glucose levels necessary for energy, particularly for vital organs like the brain.

In contrast, the other options reflect physiological processes that are not the primary role of glucagon. For example, increasing glycogen synthesis is a response to insulin signaling, not glucagon, which is antagonistic to this process. Inhibiting protein synthesis and stimulating fatty acid storage are not direct effects of glucagon; instead, glucagon's primary function is to mobilize glucose stores to provide