What is the function of adrenaline?

Adrenaline is a hormone which is secreted by the adrenal glands .When body undergoes very high level of stress or life threatening conditions, it is  secreted by the stimulation from central nervous system,. It is a part of body's stress response. It increases the heart beat rate, contracts blood vessel and dilates the air passages. These all result in the increased blood flow and increased oxygen supply. It helps body to fight and recover.