Physiology 3120 Lecture Notes - Lecture 3: Thyroid Peroxidase, Thyroid, Thyroglobulin
7 Mar 2017
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The thyroid gland: found in neck, largest endocrine gland, controls how quickly we use energy, slow acting hormone (also takes long to correct deficiencies/excess, stores iodine, produces t3/t4 and calcitonin. Thyroglobulin (tg: high mw (660 kd, glycosylated, 2 subunits, ~330 tyrosine residues, harbours carrier protein used to produce tri-iodo-thyronine (t3)/thyroxine (t4, histology, cuboidal epithelium, parafollicular cells outside of follicles. The importance of iodine: we require ~60mg iodine/day, major sources are from salt, seafood, dark green vegetables (i. e. kelp) Important role in the production of thyroid hormones (t3/t4) for growth, physical and mental development. After stimulation, these hormones are brought in via pinocytosis. Uncoupled from tg and t3 + t4 are secreted into circulation. Iodinated tg (in lysosomes) is proteolytically processed within the thyroid cell. Thyroid hormone transport: tbg and ttr regulate the bioavailability and half-life of t3/t4, tbg mainccarrier protein, without binding proteins, thyroid hormones are rapidly cleared from circulation.
