( ( As ( ( blood flow ) ( to ( the ( lungs increases ) ) ) ) ) ( , ( ( ( the amount ) ( of blood ) ) ( ( flow ( entering ( the ( left ( atrium increases ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (NP (NN blood) (NN flow)) (PP (TO to) (NP (DT the) (NNS lungs) (NNS increases))))) (, ,) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN blood)))) (VP (NN flow) (S (VP (VBG entering) (NP (DT the) (JJ left) (NN atrium) (NNS increases))))) (. .)))
As blood flow to the lungs increases, the amount of blood flow entering the left atrium increases.
(ROOT (S (NP (NP (NNP Blood)) (PP (IN from) (NP (DT the) (NNS lungs)))) (VP (VBZ enters) (PP (IN into) (NP (DT the) (JJ left) (NN atrium)))) (. .)))