Adrenaline is a natural stimulant made in the adrenal gland of the kidney. Its biological name is epinephrine, from the Greek
nephros for kidney. Adrenaline is carried in the bloodstream and affects the autonomous nervous system, which controls
functions such as the heart rate, dilation of the pupils, and secretion of sweat and saliva.

Fight or Flight?

Adrenaline is the body's activator, and is released in response to anxiety, exercise, or fear. This is the basis of the so-called
'fight-or-flight' reaction. When an animal is threatened, the options are usually either to stand its ground and fight, or run away
as fast as possible. Both responses would require extra supplies of blood and oxygen in the muscles. Fright causes the brain to
send signals to the renal glands which start pumping large amounts of adrenalin into the bloodstream. This increases the heart
and breathing rate in preparation for the ensuing action.