Yes, RESORPTION is a Scrabble word!

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

Is it a valid word?

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

the organic process in which the substance of some differentiated structure that has been produced by the body undergoes lysis and assimilation

Not playable in Scrabble US: REABSORPTION.