( ( ( The oxygen ) ( in ( the ( ( blood and ) brain ) ) ) ) ( ( is ( ( decreased ( while ( ( the levels ) ( of ( carbon dioxide ) ) ) ) ) ( in ( the ( body increase ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN oxygen)) (PP (IN in) (NP (DT the) (NX (NX (NN blood)) (CC and) (NX (NN brain)))))) (VP (VBZ is) (VP (VBN decreased) (PP (IN while) (NP (NP (DT the) (NNS levels)) (PP (IN of) (NP (NN carbon) (NN dioxide))))) (PP (IN in) (NP (DT the) (NN body) (NN increase))))) (. .)))
The oxygen in the blood and brain is decreased while the levels of carbon dioxide in the body increase.
(ROOT (S (NP (DT The) (NN brain)) (VP (VBP stem) (S (NP (NP (NN monitor)) (PRN (-LRB- -LRB-) (PRP s) (-RRB- -RRB-))) (NP (NP (DT the) (NN level)) (PP (IN of) (NP (NP (NN carbon) (NN dioxide)) (PP (IN in) (NP (DT the) (NN blood)))))))) (. .)))