Term
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Definition
| Made up of thryoglobulin. Fills the lumen of thyroid gland follicules. |
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Term
| What is the avg dietary intake of iodide? |
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Definition
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Term
| What is the Wolff Chaikoff Effect? |
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Definition
| It occurs when iodide intake exceeds 2mg/day. Excess iodide in the thyroid inhibits the iodide trap and hormone synthesis |
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Term
| How does the thyroid gland retain iodide? |
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Definition
| By conjugating it to tyrosines on thyroglobulin. |
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Term
| What are the average contents of one thyroglobulin molecule? |
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Definition
| 7 MIT, 6 DIT, 2 T4 and 0.2 T3 |
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Term
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Definition
| In the cell, most T4 is converted to T3. T3 is more potennt. TR binds T3 with a 10 fold higher affinity than T4. |
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Term
| What does the TRE Thyroid Regulatory Element do? |
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Definition
| It binds the Thyroid Receptor TR to repress gene expression down stream. When bound to ligand, it dissociates. |
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Term
| What happens when TSH receptor is stimulated? |
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Definition
1. Thyroglobulin and peroxidase synthesis
2. iodide trapping
3. T3, T4 synthesis
4. Colloid endocytosis
5. Thyroglobulin proteolysis
6. T3, T4 release
7. Thyroid gland development and vascularization |
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Term
| How are the thyrotropes in the ant. pituitary regulated? |
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Definition
| Via TRH Thyrotropin Releasing Hormone. TRH binds to GCPR and activates PLC. The activated thyrotropes synthesize and secrete TSH |
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Term
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Definition
| It is an enlargement of the thyroid gland in response to TSH. |
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Term
| What are the 3 ways in which goiter can come about, and how? |
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Definition
1. Hypothyroid - iodine deficiency causes a decrease in thyroid hormone. The pituitary senses a drop in T4 and increases TSH synthesis. The TSH promotes thyroid gland growth.
2. Euthyroid - Through increased iodine trapping, the thyroid gland will re-esatblish normal T4 levels when iodine is only slightly deficient.
Hyperthyroid - Graves disease - autoimmune stimulation of TSH receptors on the thyroid follicular cells. Leads to thyroid gland hypertrophy |
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