Adrenaline. Molecular model of the hormone adrenaline, or epinephrine (formula C9H13NO3). The atoms are spherical and colour-coded: carbon (gold), hydrogen (blue), nitrogen (purple) and oxygen (red). Adrenaline is a hormone produced in the adrenal glands above the kidneys. It is released at times of stress or fear to allow the body to work harder for a short time, leading to a fight or flight" response. It increases the speed and force of the heartbeat, widens the airways to allow the lungs to take in more oxygen, and directs blood to the muscles to allow them to work harder. As a drug, it is used to treat severe asthma and anaphylactic shock."