Adrenaline

Adrenaline is a hormone released during sudden arousal and emergency responses. In a moment of danger it comes into play within seconds; it speeds up the heart, sharpens attention, and prepares the body for quick action. It is one of the physiological engines of the fight-or-flight response. Adrenaline is the chemical that ignites the body's emergency system. When the danger passes, in a healthy system this arousal too slowly subsides.