Glucagon

Glucagon is a hormone secreted by the Alpha Cells of the Islets of the Langerhans within the pancreas, an endocrine gland in the human body.

The presence in the blood of hormone glucagon causes an increase in the quantity of sugar in the blood (blood sugar level). That is, glucagon in the bloodstream has the opposite effect to that of insulin (which regulates the amount of sugar in the blood so that there is not too much sugar present in it).

Glucagon increases blood sugar (or "blood glucose") levels when they fall below the typically "normal" level i.e. in the range 4-10 m.mol/litre, in the following ways:

• Accelerating the conversion of glycogen in the liver into glucose.
• Promoting the conversion in the liver of amino acids and lactic acid into glucose.
• Stimulating the release of glucose from the liver into the blood.

Glucagon is administered by injection to counteract diabetic hypoglycaemia.

See also: What is a Hormone ?

For further general information including the locations of the endocrine glands, see the Endocrine Glands of the Human Body.