( ( ( ( ( ( ( ( transport systems ) , ) ( ion channels ) ) , ) and ) membrane ) excitability ) ; )
(ROOT (NP (NP (NN transport) (NNS systems)) (, ,) (NP (NN ion) (NNS channels)) (, ,) (CC and) (RB membrane) (NP (NN excitability)) (: ;)))
transport systems, ion channels, and membrane excitability;
(ROOT (NP (NP (NP (NNP Ion) (NNP channels) (NNP facilitate)) (PRN (-LRB- -LRB-) (PRP s) (-RRB- -RRB-))) (NP (NP (DT the) (NN diffusion)) (PP (IN of) (NP (NP (NNS ions)) (PP (IN across) (NP (DT a) (NN membrane)))))) (. .)))