Glycogen is the storage form of carbohydrates in animals. The major sites of storage are liver and muscle.
Glucagon is a polypeptide hormone, it is secreted by the alpha cells of the pancreas. Low blood glucose causes glucagon secretion. When blood glucose level falls, liver glycogen is broken and help to maintain blood glucose level.
Glucagon stimulates the enzyme glycogen phospholylase which breaks down glycogen into glucose units.
