What is the action of glucagon on blood glucose levels?

Glucagon plays a crucial role in regulating blood glucose levels, especially during fasting or in between meals. When blood glucose levels drop, glucagon is released from the alpha cells of the pancreas. Its primary action is to raise blood glucose levels through two main mechanisms: glycogenolysis and gluconeogenesis.

Glycogenolysis is the process where glycogen, the stored form of glucose in the liver, is broken down into glucose molecules that can be released into the bloodstream. This helps to quickly elevate blood glucose levels to meet the body's energy demands.

Additionally, glucagon stimulates gluconeogenesis, which is the production of glucose from non-carbohydrate sources, such as amino acids and glycerol. This further contributes to increasing blood glucose levels, especially during prolonged fasting or low-carbohydrate intake.

Together, these actions ensure a steady supply of glucose to vital organs, particularly the brain, which relies heavily on glucose for energy. Therefore, the correct answer indicates that glucagon raises blood glucose levels by promoting both glycogenolysis and gluconeogenesis.