Where does glucagon primarily act to raise blood glucose?

Where does glucagon primarily act to raise blood glucose?

• A. Muscle tissue
• B. Adipose tissue
• C. Liver
• D. Kidneys

Answer: (C)

Glucagon’s main job is to raise blood glucose by signaling the liver. When it binds to receptors on hepatocytes, it activates a cAMP-PKA pathway that triggers glycogenolysis (breaking down stored glycogen) and gluconeogenesis (making glucose from non-carbohydrate sources). The liver has glucose-6-phosphatase, allowing the final step to release free glucose into the bloodstream, which raises blood glucose levels. Muscle tissue doesn’t export glucose to the blood because it lacks glucose-6-phosphatase, so glucagon’s effects there don’t raise blood glucose. Adipose tissue responds to glucagon less directly in terms of glucose production, and kidney gluconeogenesis can occur but is a smaller contributor compared to the liver, especially under normal fasting conditions.

Glucagon’s main job is to raise blood glucose by signaling the liver. When it binds to receptors on hepatocytes, it activates a cAMP-PKA pathway that triggers glycogenolysis (breaking down stored glycogen) and gluconeogenesis (making glucose from non-carbohydrate sources). The liver has glucose-6-phosphatase, allowing the final step to release free glucose into the bloodstream, which raises blood glucose levels.

Muscle tissue doesn’t export glucose to the blood because it lacks glucose-6-phosphatase, so glucagon’s effects there don’t raise blood glucose. Adipose tissue responds to glucagon less directly in terms of glucose production, and kidney gluconeogenesis can occur but is a smaller contributor compared to the liver, especially under normal fasting conditions.