Epinephrine (also referred to as Adrenaline; see Terminology) is a hormone and neurotransmitter. When produced in the body it increases heart rate, contracts blood vessels and dilates air passages and participates in the "fight or flight" response of the sympathetic nervous system. It is a catecholamine, a sympathomimetic monoamine produced only by the adrenal glands from the amino acids phenylalanine and tyrosine