( ( Certain ( ( fumes and ) vapors ) ) ( ( can ( ( ( ( cause ( ( the ( blood vessels ) ) ( of ( the ( susceptible person ) ) ) ) ) ( to ( ( swell and ) dilate ) ) ) , ) ( triggering ( a ( migraine headache ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Certain) (NNS fumes) (CC and) (NNS vapors)) (VP (MD can) (VP (VB cause) (NP (NP (DT the) (NN blood) (NNS vessels)) (PP (IN of) (NP (DT the) (ADJP (JJ susceptible)) (NN person)))) (S (VP (TO to) (VP (VB swell) (CC and) (VB dilate)))) (, ,) (S (VP (VBG triggering) (NP (DT a) (JJ migraine) (NN headache)))))) (. .)))
Certain fumes and vapors can cause the blood vessels of the susceptible person to swell and dilate, triggering a migraine headache.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NP (NN blood) (NNS vessels)) (PP (IN in) (NP (DT the) (NN head)))) (VP (VBP dilate)))) (, ,) (NP (NP (DT a) (NN migraine)) (, ,) (NP (DT a) (JJ severe) (NN headache)) (, ,)) (VP (MD can) (VP (VB occur))) (. .)))