Handout 40

Handout 40 - Handout4 [email protected] Thyroidhormone...

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Handout 4 [email protected] 18:15 Thyroid hormone TRH -> TSH -> T3 and T4 T3 and T4 inhibit the release of TRH and TSH Iodine is necessary for the production of thyroid hormones If not enough iodine is present then less T3 and T4 will be made The follicular cells use a secondary active transport mechanism to trap Iodine  On the basolateral membrane:  NaK atpase pumps sodium out of cell and potassium into cell Sodium Iodine Symport brings sodium and iodine into cell, (energy coupled by Na) On luminal membrane Pendrin transporter is an iodine tranporter. Pumps iodine into colloid Synthesis of thyroid hormone: 1. TG is made in Rough ER – thyroglobulin (TG or TGB) 2. Sent to golgi to be packaged 3. Exocytosed into colloid 4. Iodonated by TPO- thyroid peroxidase 5. Pinocytosis of iodinated TG 6. Fusion with lysozome  forms T3 and T4 which then diffuse away 
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T3 is triiodonated and T4 is iodinated 4 times.  Mainly T4 is produced.  T4 can be converted to T3 via a iodonase.  T3 Is more potent.  Carried by protein in blood. TBG Thyroid binding globulin (don’t get confused with TGB  thyroglobulin) Functions of T3 and T4
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This note was uploaded on 04/06/2012 for the course BICD 150 taught by Professor Fortes during the Winter '09 term at UCSD.

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Handout 40 - Handout4 [email protected] Thyroidhormone...

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