ADRENALINE - A hormone produced by the adrenal medulla in mammals. It can be produced synthetically for medical purposes. Also known as epinephrine. Epinephrine is secreted by the adrenal medulla in response to low blood glucose, exercise, and stress. Epinephrine causes a breakdown of glycogen to glucose in the liver, encourages the release of fatty acids from adipose tissue, causes vasodilation of the small arteries within muscle, and increases cardiac output.