Medical Dictionary

first messenger

noun

Definition of FIRST MESSENGER

:  an extracellular substance (as the hormone epinephrine or the neurotransmitter serotonin) that binds to a cell-surface receptor and initiates intracellular activity—compare second messenger
April 01, 2015
diapause Hear it
a period of physiological dormancy
Take a 3-minute break and test your skills!
How to use a word that (literally) drives some people nuts.
Test your vocab with our fun, fast game
Ailurophobia, and 9 other unusual fears