BIOM 3200 Chapter Notes - Chapter 2: Basal Metabolic Rate, Parafollicular Cell, Thyroglobulin
19 Dec 2016
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Document Summary
Secretes thyroxine (t4) and triiodothyronine (t3) which are needed for proper growth and development, primarily responsible for determining basal metabolic rate (bmr) Located below the larynx, positioned on either side of the trachea and connected anteriorly by a medial mass called the isthmus. Consists of number spherical hollow sacs called thyroid follies which are lined with simple cuboidal epithelium composed of follicular cells that synthesize thyroxine. The interior of the follies contain colloid, a protein rich uid. Iodide is actively transported into the follicular cells. In the colloid, it is converted into iodine and attached to tyrosine amino acids within thyroglobulin protein. Mit (monoiodotyrosine) and dit (diiodotyrosine) are used to produced t3and t4 within the colloid. Upon stimulation of tsh, the thyroid hormones bound to thyroglobulin, are taken into follicular cells by pinocytosis. Hydrolysis reaction within the follicular cells release free t4 and t3 which are secreted.
