( However ( , ( it ( ( is ( known ( that ( they ( secrete ( hormones ( which ( ( ( enter ( the body ) ) ( through ( the ( circulatory system ) ) ) ) ( where ( they ( ( affect ( ( such things ) ( as ( growth ( , ( reproduction ( , ( energy ( ( levels and ) metabolism ) ) ) ) ) ) ) ) ) ( in general ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB However)) (, ,) (NP (PRP it)) (VP (VBZ is) (VP (VBN known) (SBAR (IN that) (S (NP (PRP they)) (VP (VBP secrete) (NP (NP (NNS hormones)) (SBAR (WHNP (WDT which)) (S (VP (VBP enter) (NP (DT the) (NN body)) (PP (IN through) (NP (DT the) (JJ circulatory) (NN system))) (SBAR (WHADVP (WRB where)) (S (NP (PRP they)) (VP (VBP affect) (NP (NP (JJ such) (NNS things)) (PP (IN as) (NP (NN growth) (, ,) (NN reproduction) (, ,) (NN energy) (NNS levels) (CC and) (NN metabolism)))) (PP (IN in) (NP (NN general))))))))))))))) (. .)))
However, it is known that they secrete hormones which enter the body through the circulatory system where they affect such things as growth, reproduction, energy levels and metabolism in general.
(ROOT (S (NP (NNS Hormones)) (ADVP (RB generally)) (VP (VBP travel) (PP (IN through) (NP (NP (DT the) (JJ circulatory) (NN system) (NN system)) (PP (IN of) (NP (DT the) (NN body)))))) (. .)))