( Blood ( ( ( ( flows back ) ( into ( ( the heart ) ( from ( ( the lungs ) ( ( ( ( through ( the ( left atrium ) ) ) , ) and ) ( from ( ( the rest ) ( of ( the body ) ) ) ) ) ) ) ) ) ) ( through ( ( ( the ( venae cavae ) ) and ) ( the ( right atrium ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Blood)) (VP (VBZ flows) (PRT (RP back)) (PP (IN into) (NP (NP (DT the) (NN heart)) (PP (IN from) (NP (NP (DT the) (NNS lungs)) (PP (PP (IN through) (NP (DT the) (JJ left) (NN atrium))) (, ,) (CC and) (PP (IN from) (NP (NP (DT the) (NN rest)) (PP (IN of) (NP (DT the) (NN body)))))))))) (PP (IN through) (NP (NP (DT the) (JJ venae) (NN cavae)) (CC and) (NP (DT the) (JJ right) (NN atrium))))) (. .)))
Blood flows back into the heart from the lungs through the left atrium, and from the rest of the body through the venae cavae and the right atrium.
(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)))) (. .)))