Adrenaline; a hormone that increases heart rate and prepares the body for 'fight or flight' responses.
From Latin 'ad-' (to) + 'nephros' (kidney, from Greek). The name references where this hormone is produced: the adrenal glands (literally 'at the kidneys').
The modern name 'adrenaline' replaced the original 'adnephrine,' but the old name perfectly explains the anatomy—'ad' means toward and 'nephrine' from kidneys, so it literally means 'at-kidney hormone!' Your body floods you with it before a big test.
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