( It ( ( studies ( ( the relationship ) ( between ( ( ( ( ( ( the ( body systems ) ) , ) pathogens ) , ) and ) immunity ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ studies) (NP (NP (DT the) (NN relationship)) (PP (IN between) (NP (NP (DT the) (NN body) (NNS systems)) (, ,) (NP (NNS pathogens)) (, ,) (CC and) (NP (NN immunity)))))) (. .)))
It studies the relationship between the body systems, pathogens, and immunity.
(ROOT (S (NP (DT The) (JJ innate) (JJ immune) (NN system)) (VP (VBZ serves) (PP (IN as) (NP (NP (DT a) (JJ first) (NN responder)) (PP (TO to) (NP (NP (JJ pathogenic) (NNS threats)) (SBAR (WHNP (WDT that)) (S (VP (VB bypass) (NP (NP (JJ natural) (ADJP (NN physical) (CC and) (NN chemical)) (NNS barriers)) (PP (IN of) (NP (DT the) (NN body)))))))))))) (. .)))