Adrenaline is released from the adrenal medulla in response to the activation of the sympathomedullary pathway, in response to acute stress. The direct effects of adrenaline include the increase of heart rate, constriction of the vascular system resulting in raised blood pressure. The release of adrenaline informs the body to divert blood away from unnecessary systems, such as the digestive system, to conserve energy in preparation to fight or flight. Adrenaline also increases respiration and sweating. All these direct effects have a more overall effect preparing the body for action, fight or flight.