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T 3 is the more metabolically active hormone produced from T 4.T 4 is deiodinated by three deiodinase enzymes to produce the more-active triiodothyronine: . Type I present in liver, kidney, thyroid, and (to a lesser extent) pituitary; it accounts for 80% of the deiodination of T 4.
Effect Growth hormone (somatotropin) GH: Somatotrophs: Stimulates growth and cell reproduction Stimulates Insulin-like growth factor 1 release from liver: Thyroid-stimulating hormone (thyrotropin) TSH: Thyrotropes: Stimulates thyroxine (T4) and triiodothyronine (T3) synthesis and release from thyroid gland Stimulates iodine absorption by ...
liver, kidney, striated muscle: Myocytes: TPO receptor: megakaryocytes: produce platelets [6] 60 Thyroid-stimulating hormone (or thyrotropin) TSH Peptide: anterior pituitary: thyrotropes: Thyrotropin receptor → cAMP: thyroid gland: secrete thyroxine (T 4) and triiodothyronine (T 3) 61 Thyrotropin-releasing hormone: TRH Peptide: hypothalamus ...
3,3'-Diiodothyronine, also known as 3,3'-T 2, is a metabolite of thyroid hormone. It is formed from the breakdown of triiodothyronine . Levels can be affected in certain disease states.
Three related isoforms, deiodinase type I, II, and III, contribute to activation and inactivation of the initially released hormone precursor T 4 into T 3 (triiodothyronine) or rT 3 (reverse triiodothyronine) in target cells. The enzymes catalyze a reductive elimination of iodine (the different isoforms attack different thyronine positions ...
Inactivation of thyroid hormones occurs by removal of an iodine atom on the inner ring, which converts thyroxine to the inactive reverse triiodothyronine (rT 3), or which converts the active triiodothyronine to diiodothyronine (T 2). The major part of thyroxine deiodination occurs within the cells. Deiodinase 2 activity can be regulated by ...
The pituitary gland secretes thyrotropin (TSH; Thyroid Stimulating Hormone) that stimulates the thyroid to secrete thyroxine (T4) and, to a lesser degree, triiodothyronine (T3). The major portion of T3, however, is produced in peripheral organs, e.g. liver, adipose tissue, glia and skeletal muscle by deiodination from
TSH (with a half-life of about an hour) stimulates the thyroid gland to secrete the hormone thyroxine (T 4), which has only a slight effect on metabolism. T 4 is converted to triiodothyronine (T 3), which is the active hormone that stimulates metabolism. About 80% of this conversion is in the liver and other organs, and 20% in the thyroid ...