Transcript Slide ()

Mechanism of iodide concentration by the thyroid gland. Iodide is transported into the cytosol of the follicular cell by a sodium-iodide (Na+/I−) symporter.
Two Na+ ions are transported inside the thyroid follicular cell with each iodide molecule. Na+ moves down its concentration gradient, which is maintained
by a Na+/K+-ATPase that constantly pumps Na+ out of the cytoplasm of the thyroid follicular epithelial cell maintaining the low intracytoplasmic Na+
concentrations. Iodide must reach the colloid space, where it is used for organification of thyroglobulin. This process is achieved by efflux through the
iodide channel. One of the early effects of thyroid-stimulating hormone (TSH) binding to its receptor is the opening of these channels facilitating the leak of
iodide into the extracellular space. This transcellular transport of iodide relies on the functional and morphological polarization of the thyroid follicular
Source: Chapter 4. Thyroid Gland, Endocrine Physiology, 4e
epithelial cell.
Citation: Molina PE. Endocrine Physiology, 4e; 2013 Available at: http://mhmedical.com/ Accessed: March 20, 2017
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