Explain the Regulation of Thyroid Hormone Secretion

TSH from the anterior pituitary gland controls the secretion of thyroid hormones. Thyrotropin Releasing Factor (TRF) from the hypothalamus stimulates TSH. When the level of thyroid hormones in the blood is increased, it inhibits the anterior pituitary secretion of TSH by a direct effect on the anterior pituitary itself (negative feedback) and by indirect effect acting throughout the hypothalamus. Of the various stimuli increasing TSH secretion, exposure to cold is one of them and is very important.