Structure:
Glucagon is a hormone composed of 29 amino acids. It is secreted by the
alpha cells in the Islets of Langerhan.
in the pancreas. Low levels of the humoral
transmitter, glucose, stimulates glycogen release, and so do high levels
of amino acids after a meal. Release is slowed by glucose and by somatostatin.
Function:
Glycogen strongly antagonizes the action of insulin. It does this by promoting
the liver to break down glycogen
(glycogenolysis) from storage, increase production of glucose from lactic
acid, amino acids, and fats (glyconeogenesis), and release glucose into
the circulation. It also promotes removal of circulating amino acids to
synthesize glucose in the liver.
