Noradrenaline, also called norepinephrine, is a hormone produced by the medulla of the adrenal gland. Along with adrenaline, noradrenaline effects the fight-or-flight response. It activates the sympathetic nervous system, which increases the concentration of glucose in the blood, raises blood pressure and heartbeat rate, and increases muscular power and resistance to fatigue. Noradrenaline is also one of the principal neurotransmitters in the nervous system where it is released from noradrenergic neurons during synaptic transmission.
An injection of noradrenaline may sometimes be given in the emergency treatment of shock or severe bleeding.