During periods of stress, such as preparing to run in a race, the brain signals the adrenal glands to produce epinephrine or "adrenaline". Epinephrine increases the rate in which the heart beats. The increased cardiac output supplies more oxygen to the muscles, putting the body a heightened state to react. As a longer term response to stress, cortisol is secreted by the adrenal glands, promoting the release of energy.
Reviewed last on: 10/10/2008
Larry A. Weinrauch, MD, Assistant Professor of Medicine, Harvard Medical School, and Private practice specializing in Cardiovascular Disease, Watertown, MA. Review provided by VeriMed Healthcare Network.