epinephrine

/ˈɛpɪˌnɛfrən/

Epinephrine is a hormone that's released by the adrenal glands in response to stress. If you've ever felt your heart pounding fast after hearing a scary sound in the dark, you've experienced a surge of epinephrine.

Epinephrine is another name for adrenaline. This is the hormone involved in "fight or flight" responses to dangerous or scary situations. It's also the name of a synthetic form of the hormone that's used as a medication. Someone who's having a severe allergic reaction to peanuts or shellfish might need an injection of epinephrine to reverse the symptoms. The Greek roots of epinephrine mean "upon the kidney," a reference to the location of the adrenal glands.

Definitions of epinephrine

1. noun

   a catecholamine secreted by the adrenal medulla in response to stress (trade name Adrenalin); stimulates autonomic nerve action
   synonyms: Adrenalin, adrenaline, epinephrin

   type of:

   pressor, vasoconstrictive, vasoconstrictor

   any agent that causes a narrowing of an opening of a blood vessel: cold or stress or nicotine or epinephrine or norepinephrine or angiotensin or vasopressin or certain drugs; maintains or increases blood pressure

   endocrine, hormone, internal secretion

   the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect

   neurotransmitter

   a neurochemical that transmits nerve impulses across a synapse

   catecholamine

   any of a group of chemicals including epinephrine and norepinephrine that are produced in the medulla of the adrenal gland