Epinephrine (also referred to as adrenaline; see Terminology) is a hormone and neurotransmitter.Epinephrine increases the "fight or flight" response of the sympathetic division of the autonomic nervous system.It is a catecholamine, a sympathomimetic monoamine derived from the amino acids phenylalanine and tyrosine. The Latin roots ad-+renes and the Greek roots epi-+nephros both literally mean "on/to the kidney" (referring to the adrenal gland, which sits atop the kidneys and secretes epinephrine