Yes, RECEPTORS is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, C 3, E 1, P 3, T 1, O 1, R 1, S 1.

Is it a valid word?

RECEPTORS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

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
an organ having nerve endings (in the skin or viscera or eye or ear or nose or mouth) that respond to stimulation

Also: sense organ, sensory receptor.