After glucagon is released, it primarily triggers a cascade of events that ultimately raise blood sugar levels. Specifically, glucagon signals the liver to increase glucose production.
The Liver's Response to Glucagon
The liver responds to glucagon in the following ways:
- Glycogenolysis: The liver breaks down glycogen (its stored form of glucose) into glucose. This is the primary and quickest way glucagon raises blood sugar.
- Gluconeogenesis: The liver synthesizes new glucose from other sources, such as amino acids, lactate, and glycerol. This process is slower than glycogenolysis but crucial for sustained blood sugar levels if glycogen stores are depleted.
The Result: Increased Blood Sugar
The glucose produced by the liver is then released into the bloodstream, increasing the blood glucose concentration. This process helps to counteract hypoglycemia (low blood sugar).
Other Effects of Glucagon
While the primary effect of glucagon is on the liver, it can also have minor effects on other tissues:
- Adipose tissue: Glucagon can stimulate lipolysis (breakdown of stored fat), releasing fatty acids and glycerol into the bloodstream. These can be used as alternative energy sources.
- Kidneys: Glucagon can affect electrolyte balance in the kidneys, although this is a less significant effect.
In summary, glucagon initiates a response primarily in the liver to elevate blood glucose levels, mainly through glycogenolysis and gluconeogenesis, thus preventing or correcting hypoglycemia.