1. What is the main function of the thyroid gland?

Regulation of the metabolism

2. What three hormones secreted by the thyroid gland regulate metab?

thyroxine (T4), triiodothyronine (T3), and calcitonin

3. what is the relationship between T3 and T4?

closely related and work at the same receptor, however T3 is more potent but more short lived, while T4 has to be converted to T3 at the receptr

4. What is the circulation of iodine as related to the thyroid gland?

T4 and T3 contain iodine, ingested iodine is absorbed in the GI tract, enters the circulation and is taken up by the iodine pump by the thyroid follucular cells for hormone synthesis

5. Where is T3 and T4 synthesized?

synthesized from thyroglobulin in the follicle cells (main produce of thyroid cells) which is stored in colloid

6. What is the process of T3 and T4 synthesis?

Iodine transported into cell --> peroxidase iodination links iodine to thyroglobulin --> peroxidase coupling action creates T3 and T4 molecules of the thyroglobulin, which is stored in the colloid

7. What happens when T3 and T4 needs to be secreted?

endocytosis into the follicular cell from thyroid --> ceaved by endocytosis proteolysis to T3 and T4 released from the follicular cell

8. Where do T3 and T4 target the body?

diffuse effects - no specific target organ or tissue

9. What long term functions are regulated by thyroid hormones?

growth and maturation, CNS system function, basal metabolic rate, cardiovascular function, temperature regulation

10. What is the effect of T3 of genes?

regulates gene expression, high lipid soluble; binds to T3 receptor and turns on/off protein synthesis within the cell