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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.
The hypothalamic–pituitary–thyroid axis ( HPT axis for short, a.k.a. thyroid homeostasis or thyrotropic feedback control) is part of the neuroendocrine system responsible for the regulation of metabolism and also responds to stress. As its name suggests, it depends upon the hypothalamus, the pituitary gland, and the thyroid gland .
The major form of thyroid hormone in the blood is thyroxine (T 4), whose half-life of around one week [4] is longer than that of T 3. [5] In humans, the ratio of T 4 to T 3 released into the blood is approximately 14:1. [6] T 4 is converted to the active T 3 (three to four times more potent than T 4) within cells by deiodinases (5′-deiodinase).
Human thermoregulation. As in other mammals, human thermoregulation is an important aspect of homeostasis. In thermoregulation, body heat is generated mostly in the deep organs, especially the liver, brain, and heart, and in contraction of skeletal muscles. [ 1] Humans have been able to adapt to a great diversity of climates, including hot ...
The hypothalamus ( pl.: hypothalami; from Ancient Greek ὑπό (hupó) 'under' and θάλαμος (thálamos) 'chamber') is a small part of the vertebrate brain that contains a number of nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland.
Thyroid follicular cells (also called thyroid epithelial cells or thyrocytes[ 1]) are the major cell type in the thyroid gland, and are responsible for the production and secretion of the thyroid hormones thyroxine (T 4) and triiodothyronine (T 3 ). They form the single layer of cuboidal epithelium that makes up the outer structure of the ...
Parafollicular cells, also called C cells, are neuroendocrine cells in the thyroid. They are called C cells because the primary function of these cells is to secrete calcitonin. [ 1] They are located adjacent to the thyroid follicles and reside in the connective tissue. These cells are large and have a pale stain compared with the follicular cells.
Normal human body temperature ( normothermia, euthermia) is the typical temperature range found in humans. The normal human body temperature range is typically stated as 36.5–37.5 °C (97.7–99.5 °F). [ 8][ 9] Human body temperature varies. It depends on sex, age, time of day, exertion level, health status (such as illness and menstruation ...