( ( negative ( feedback Changes ) ) ( ( are ( ( ( ( reversed and ) returned ) ( to ( normal levels ) ) ) ( to ( keep ( conditions stable ) ) ) ) ) . ) )
(ROOT (S (NP (JJ negative) (NN feedback) (NNS Changes)) (VP (VBP are) (VP (VBN reversed) (CC and) (VBN returned) (PP (TO to) (NP (JJ normal) (NNS levels))) (S (VP (TO to) (VP (VB keep) (S (NP (NNS conditions)) (ADJP (JJ stable)))))))) (. .)))
negative feedback Changes are reversed and returned to normal levels to keep conditions stable.
(ROOT (S (NP (JJ Positive) (NN feedback)) (VP (VP (VBZ intensifies) (NP (NP (DT a) (NN change)) (PP (IN in) (NP (NP (DT the) (NN body) (POS 's)) (JJ physiological) (NN condition))))) (CONJP (RB rather) (IN than)) (VP (VBG reversing) (NP (PRP it)))) (. .)))