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Part 4

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waveurflag's version from 2018-03-29 02:10

Section

Question Answer
Production of Thyroid Hormones in Thyroid Follicular Cells• Need iodide to reach thyroid follicle • Basolateral – need symporter to uptake iodide from blood o Na/I symporter  iodide to thyroid follicle • Pendrine – iodine transporter to luminal side • Iodide reduction o Iodide needs to be oxidized o Thyroid peroxidase oxidizes iodide • Nucleus surrounded by ER o ER will secrete thyroglobulin o Thyroglobulin is the backbone of T3 and T4: it attracts oxidized iodide so the thyroid can build T3 and T4 • Positional rearrangement will cause iodide and backbone will create T3 or T4 • Backbone gets released to form complete T3 (triiodothyronine) or T4 (thyroxine) and will be released back into the blood through endocytosis
thyroglobulinis the backbone of T3 and T4: it attracts oxidized iodide so the thyroid can build T3 and T4
5’Deiodinaseenzyme that converts T4 to T3 to activate thyroid hormone • Enzyme is not specific. Will remove either iodide. o T3 – when correct one is removed o Reverse T3 – when other iodide is removed: no activity!
o Inhibit thyroid production through Thoamides  Iodides  Beta-blockers  Anion inhibitos  Radioactive iodine
Methimazoleinhibits the enzyme thyroperoxidase (prevents oxidation of the iodide anion) • Indirectly prevents iodine's addition to tyrosine residues on the hormone precursor thyroglobulin (prevents binding to backbone) • Prevents a necessary step in the synthesis of triiodothyronine (T3) and thyroxine (T4).
• Methimazole has been demonstrated to potently inhibit all CYP450 enzymes
Methimazole side effectsfever or sore throat while taking it• This could indicate the development of agranulocytosis, an uncommon but severe side effect resulting from a drop in the white blood cell count
Anion Inhibitors• Monovalent anions (perchlorate ClO4-) o (environmental contaminants, not a drug) • Block uptake iodide through transport
Iodides .• Prevent proteolysis to release hormones
Beta-Blockers• Beta blockers, high dose propylthiouracil • And steroids inhibit 5’-deiodinase • Also several symptoms of hyperthyrpoidism is shared by sympathetic stimulation
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