Source : WordNet®

receptor
     n 1: a cellular structure that is postulated to exist in order to
          mediate between a chemical agent that acts on nervous
          tissue and the physiological response
     2: an organ having nerve endings (in the skin or viscera or eye
        or ear or nose or mouth) that respond to stimulation [syn:
         {sense organ}, {sensory receptor}] [ant: {effector}]