( They ( ( play ( ( an ( important role ) ) ( in ( ( the function ) ( of ( the ( nervous system ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBP play) (NP (NP (DT an) (JJ important) (NN role)) (PP (IN in) (NP (NP (DT the) (NN function)) (PP (IN of) (NP (DT the) (JJ nervous) (NN system))))))) (. .)))
They play an important role in the function of the nervous system.
(ROOT (S (NP (DT The) (JJ nervous) (NN system)) (VP (VBZ plays) (NP (NP (DT a) (JJ critical) (NN role)) (PP (IN in) (NP (NP (DT the) (NN regulation)) (PP (IN of) (NP (NN vascular) (NNS homeostasis))))))) (. .)))