Negative  feedback in thyroid
   hormones.
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   Thyroid  hormones  are involved in many metabolic functions, including
   maintain temperature homeostasis.
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   When    body    temperature    drops,    the   hypothalamus   secretes
   thyroid-releasing hormone (TRH).
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   TRH  stimulates  the anterior pituitary to secrete thyroid-stimulating
   hormone (TSH).
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   TSH  then  stimulates  the  thyroid  gland  to  synthesize the thyroid
   hormones T[3] and T[4].
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   T[3]  and T[4] in turn exert negative feedback on the hypothalamus and
   anterior pituitary and inhibit release of TRH and TSH.
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