What is glucagon?

Glucagon is a hormone produced by the alpha cells in the islets of Langerhan cells in the pancreas and it signals to the liver to convert glycogen to glucose (glycogenolysis) which is then released into the bloodstream to increase the blood sugar level. It is released when the blood glucose level drops below normal levels, usually during strenuous exercise or when fasting.

A hormone that converts stored glycogen to glucose

Glucagon is a hormone in the body which causes stored glycogen to be converted into glucose. When blood sugar levels are low the pancreas releases glucagon into the bloodstream. This causes glycogen stores in the liver and muscles to break down into glucose (glycogen is simply a long chain of glucose molecules joined together). This release of glucose into the blood restores the blood sugar level back to normal.

Glucagon is hormone formed in the pancreas which promotes the breakdown of glycogen to glucose in the liver.

Glucagon is a hormone that is involved in controlling blood sugar (glucose) levels. It is produced by the alpha cells, found in the islets of Langerhans, in the pancreas, from where it is released into the bloodstream.

So what is the action of glucagon? The pancreas detects low blood glucose concentration and this may happen if you haven't eaten for a while. Alpha cells in the pancreas secrete glucagon. Glucagon (1st messenger) travels in the bloodstream and binds with complimentary glycoprotein receptors on liver cells to form a hormone receptor complex (HRC). HRC causes a membrane bound enzyme to change in tertiary structure and the active site consequently becomes complementary to ATP. ATP is then converted to cAMP (2nd messenger) (Adenylate cyclase catalyses the cyclization of ATP to cAMP. cAMP activates protein enzyme kinase which converts glycogen to glucose. Glucose moves out of the cell by facilitated diffusion and the blood glucose concentration goes back to normal. This is an example of negative feedback.