Adrenaline is a stress hormone produced within the adrenal gland that accelerates the heart beat, strengthens the force of the heart's contraction, and open up the bronchioles in the lungs. The secretion of adrenaline is part of the human "fight or flight" response to stressor like fear, panic or perceived threat. It is also know as epinephrine. It acts by binding to a variety of adrenergic receptors which triggers a number of metabolic changes. Binding to alpha adrenergic receptors inhibits insulin secretion by the pancreas, stimulates glycogenolysis in the liver and muscle, and stimulates glycolysis and inhibits insulin mediated glycogenesis in muscle. Beta adrenergic receptor binding triggers glucagon secretion in the pancreas, increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland, and increased lipolysis by adipose tissue. Overall, these effects lead to increased blood glucose and fatty acids providing substrates for energy production within cells throughout the body. With the process discussed above, we can say that the adrenaline plays as a signal molecule.
