Krista wonders if TSH is a thyroid hormone and Dr Weisman ex

Krista wonders if TSH is a \"thyroid hormone,\" and Dr. Weisman explains that it is not. State the: action of thyroid-stimulating hormone (TSH) and name the gland that secretes it. How is the secretion of TSH regulated under normal conditions?

Solution

Thyroid-stimulating hormone (TSH) is produced by the pituitary thyrotrophs. The name of the hormone suggests that it is a stimulating hormone i.e. activation hormone; which stimulates thyroid hormone specially thyroxine (T₄). The process of stimulation starts from hypothalamus, which produces thyrotropin-releasing hormone (TRH) that stimulates pituitary for secretion of TSH. Now this TSH moves to secrete thyroid hormone by stimulating thyroid gland. The stimulation process governed by a G- protein-coupled receptor - TSH receptor, presents in the thyroid gland.

The TSH hormone is regulated by TRH of hypothalamus and the whole process is governed by negative feedback control. Under normal condition TSH stimulates by hypothalamus but when the thyroid hormone in the blood exceeded, it negatively shut down the secretion process of TSH and TRH both.