( Blood ( ( enters ( into ( ( ( the ( inferior ( vena cava ) ) ) and ) ( ( then ( the ( right atrium ) ) ) ( of ( the heart ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Blood)) (VP (VBZ enters) (PP (IN into) (NP (NP (DT the) (JJ inferior) (NN vena) (NN cava)) (CC and) (NP (NP (RB then) (DT the) (JJ right) (NN atrium)) (PP (IN of) (NP (DT the) (NN heart))))))) (. .)))
Blood enters into the inferior vena cava and then the right atrium of the heart.
(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)))) (. .)))