( ( The ( parathyroid glands ) ) ( ( ( ( ( are ( located ( behind ( the thyroid ) ) ) ) , ) and ) ( ( produce ( parathyroid hormone ) ) ( in ( response ( to ( low ( blood ( calcium levels ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ parathyroid) (NNS glands)) (VP (VP (VBP are) (VP (VBN located) (PP (IN behind) (NP (DT the) (NN thyroid))))) (, ,) (CC and) (VP (VBP produce) (NP (JJ parathyroid) (NN hormone)) (PP (IN in) (NP (NP (NN response)) (PP (TO to) (NP (JJ low) (NN blood) (NN calcium) (NNS levels))))))) (. .)))
The parathyroid glands are located behind the thyroid, and produce parathyroid hormone in response to low blood calcium levels.
(ROOT (S (NP (DT The) (CD two) (JJ parathyroid) (NNS glands)) (VP (VBP are) (VP (VBN located) (PP (IN behind) (NP (DT the) (NN thyroid) (NN gland))))) (. .)))