( ( ( ( ( Nerve cells ) ( ( transmit ( a signal ) ) ( when ( ( one cell ) ( releases ( ( a store ) ( of neurotransmitter ) ) ) ) ) ) ) and ) ( ( ( the ( next cell ) ) ( in ( the chain ) ) ) ( ( ( receives it ) , ) ( activating ( ( a ( membrane ( signal pathway ) ) ) ( that ( ( in turn ) ( generates ( an ( electrical signal ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (JJ Nerve) (NNS cells)) (VP (VB transmit) (NP (DT a) (NN signal)) (SBAR (WHADVP (WRB when)) (S (NP (CD one) (NN cell)) (VP (VBZ releases) (NP (NP (DT a) (NN store)) (PP (IN of) (NP (NN neurotransmitter))))))))) (CC and) (S (NP (NP (DT the) (JJ next) (NN cell)) (PP (IN in) (NP (DT the) (NN chain)))) (VP (VBZ receives) (NP (PRP it)) (, ,) (S (VP (VBG activating) (NP (NP (DT a) (JJ membrane) (NN signal) (NN pathway)) (SBAR (WHNP (WDT that)) (S (PP (IN in) (NP (NN turn))) (VP (VBZ generates) (NP (DT an) (JJ electrical) (NN signal)))))))))) (. .)))
Nerve cells transmit a signal when one cell releases a store of neurotransmitter and the next cell in the chain receives it, activating a membrane signal pathway that in turn generates an electrical signal.
(ROOT (S (NP (NP (DT An) (JJ electrical) (NN signal)) (PP (IN along) (NP (DT a) (NN nerve) (NN cell)))) (VP (VBZ triggers) (NP (NP (DT the) (NN secretion)) (PP (IN of) (NP (NN neurotransmitter) (NNS molecules))))) (. .)))