Function of Glucagon

The function of glucagon is to raise the amount of glucose in your bloodstream to keep it up at normal levels. It does so by making the liver cells produce glucose from glycogen first, then from fat. This fat could be in the form of triglyceride you have stored in your adipose cells or from the glycerol obtained from the fat you eat in your diet; when you eat butter, for example. Thus, this hormone is vital for blood sugar regulation and metabolism as the function it performs is the opposite of that of insulin. Glucagon is secreted by the alpha cells of the islets of Langerhans in the pancreas.

When you run or work out for more than half an hour, glucose (sugar) levels in the bloodstream begin to drop. To avoid deadly hypoglycemia, the pancreas alpha cells automatically releases glucagon, which activates hepatocytes. These metabolic liver cells in turn convert the stored glycogen back into glucose. Glycogen is the first fuel reserve. But if you keep strenuously exerting your muscles for a long period, you also run out of glycogen. Then, your body resort to tap the second fuel reserve, which is the fat stored in the form of triglyceride. This time, glucagon activates an enzyme called lipase, which is also found in the adipose tissue.

Lipase breaks each one of the molecule of triglyceride into smaller molecules: two fatty acids and one glycerol is obtained from one triglyceride. In the liver, fatty acids is further metabolized into ketone bodies, which are high-octane fuel utilized by most of the body cell mitochondria to produce ATP, the cell energy. In other words, thanks to glucagon, your body is able to burn fat to obtain high-octane fuel to produce energy, just like a thermoelectric power plant, where the boilers and turbines use fuel (gas or carbon) to turn the generators to produce AC electricity. ATP (AdenosineTriphosPhate) is the cell "electricity". By burning both glycogen and the fat you have stored in your body, you never suffer from hypoglycemia, unless you suffer from type I diabetes.

Meanwhile, the liver hepatocytes also metabolize the glycerol obtained from the fat contained in the food you eat. They convert it into glucose through a slow process called gluconeogenesis, which is the generation of sugar from glycerol.

By Carlos B. Camacho