PHYSL210B Lecture Notes - Lecture 16: Thyroid, Thyrotropin Receptor, Thyroglobulin
3 Apr 2019
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Document Summary
Thyroid gland is a primary endocrine hormone. Has two lobes joined together by tissue bridge. Cells in hypothalamus releases trh into the portal system and stimulates the anterior pituitary. Tsh travels in the systemic circulation to stimulate release of th (t3 and t4) Cold temperature in infants stimulates th secretion. In circulation majority of the th is in the form t4. T4 is converted to t3 when interacting with target. High levels of th in the blood can negatively feedback hypothalamus and pituitary gland. The colloid is largest when the thyroid gland is inactive. Iodide is brought into follicles from circulation through iodide- sodium co- transporter. Iodide is oxidised and attached to rings of tyrosine in thyroglobulin to form mit (one i in tyrosine ring) and dit (two i in tyrosine ring) The iodinated ring of one mit or dit is added to a dit at another spot. T3 (mit+ dit) and t4 (dit + dit) is packed into lysosomes.
