( ( The ( parasympathetic system ) ) ( ( ( regulates potassium ) permeability ) . ) )
(ROOT (S (NP (DT The) (JJ parasympathetic) (NN system)) (VP (VBZ regulates) (NP (NN potassium)) (ADVP (RB permeability))) (. .)))
The parasympathetic system regulates potassium permeability.
(ROOT (S (NP (DT The) (JJ parasympathetic) (NN system)) (VP (MD can) (ADVP (RB also)) (VP (VB be) (VP (VBN referred) (S (VP (TO to))) (PP (IN as) (NP (DT the) (JJ craniosacral) (NN system)))))) (. .)))