Adrenaline (epinephrine) is a hormone released by the adrenal glands in response to physical and psychological stress. It is a messenger molecule that initiates the "fight or flight" syndrome. Adrenaline causes increased blood flow to the muscles and brain , accelerates respiration and the heart rate, and stimulates the release of stored energy sources into the blood. When injury to the body occurs, it potentiates the healing process. At times, it also functions as a neurotransmitter.






