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Triiodothyronine, also known as T 3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate. [1] Production of T 3 and its prohormone thyroxine (T 4) is activated by thyroid-stimulating hormone (TSH), which is released from the anterior ...
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 ...
Thyroid hormones lead to heat generation in humans. However, the thyronamines function via some unknown mechanism to inhibit neuronal activity; this plays an important role in the hibernation cycles of mammals and the moulting behaviour of birds. One effect of administering the thyronamines is a severe drop in body temperature.
The thyroid gland is located in the front of the neck, in front of the thyroid cartilage, and is shaped like a butterfly, with two wings connected by a central isthmus. Thyroid tissue consists of follicles with a stored protein called colloid, containing thyroglobulin, a precursor to other thyroid hormones, which are manufactured within the ...
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 ...
Iodothyronine deiodinases (EC 1.21.99.4 and EC 1.21.99.3) are a subfamily of deiodinase enzymes important in the activation and deactivation of thyroid hormones. Thyroxine (T 4), the precursor of 3,5,3'-triiodothyronine (T 3) is transformed into T 3 by deiodinase activity.
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 ...