Search results
Results from the WOW.Com Content Network
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 ...
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 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 ...
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 ...
Thyroid follicular cells form a simple cuboidal epithelium and are arranged in spherical thyroid follicles surrounding a fluid filled space known as the colloid. The interior space formed by the follicular cells is known as the follicular lumen .
Triiodothyronine: T 3: Amino acid derivative peripheral tissue of thyroid gland: Thyroid follicular cell / Tyrosine: thyroid hormone receptor: nearly every cell in the body increased metabolism 5 Thyroxine: T 4: Amino acid derivative thyroid gland: Thyroid follicular cell / Tyrosine: thyroid hormone receptor: nearly every cell in the body
Thyroid hormones can have a direct inhibitory effect on thyrotropic cells, though the exact mechanism is unknown. At elevated levels of thyroxine , the rate of secretion of TSH decreases to near zero, as the body tries to maintain a relatively constant level of thyroid hormone in circulation. [ 1 ]