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5 Cards in this Set
- Front
- Back
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at the border of the apical membrane what 3 substances come together to make thyroid hormone?
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Thyroglobulin + tyrosine + iodine
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thyroid hormone synthesis (flip and read)
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Iodide is brought into the follicular cell via a sodium iodide symporter, driven by Na+ going down its concentration gradient. Iodide crosses the apical membrane and enters the colloid via the protein, pendrin. Specific tyrosine residues on thyroglobulin are iodinated at the apical membrane via the activity of thyroid peroxidase to form DIT (diiodotyrosine) and MIT (monoiodotyrosine). These reactions require H2O2, provided by the activity of thyroid oxidase. Thyroid peroxidase also catalyzes the coupling of DIT and/or MIT to form T4 or T3, respectively, stored in colloid as part of thyroglobulin. Pinocytosis of colloid leads to formation of endosomes in the cell that will be digested by lysosomes to yield T3, T4, MIT, and DIT. The T3 and T4 leave the cell via the basal membrane and enter the capillaries. MIT and DIT are deiodinated and the iodide recycled. TSH (+) almost every aspect of thyroid hormone synthesis: synthesis of thyroglobulin; expression of NIS; pinocytosis of colloid; activity of thyroid peroxidase and thyroid oxidase.
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Draw the feedback loop for thyroid hormone
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what is the active form of thyroid hormone?
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T3
(so T4 must be converted peripherally) |
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Irritability
Anxiety Heat intolerance Insomnia Eye tearing Dyspnea Heart palpitations Increased appetite, but weight loss Diarrhea Increased defecation Sweating Hair loss Amenorrhea Muscle fatigue Tremors Hyper or hypothyroid? |
HYPER
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