Thyroid Gland

Question 1

Describe the process of the release of TRH and TSH?

Answer 1

1. Under the influence of cold, circadian rhythm and stress, nuclei in hypothal produces TRH (thyroid releasing hormone)
2. TRH releases into Hypophyseal Portal system at Median Eminence
3. TRH binds to Thyrotrope cells ion Anterior Pituitary and stim prod of TSH (thyroid stimulatiing hormone)
4. TSH enters general circ and binds to receptor on thyroid epithelial cells
5. In response to TSH -> Thyroid follicle cells prod. T4 and T3

Question 2

Iodine Distribution and Turnover diagram

Answer 2

Question 3

What converts T4 to T3

Answer 3

Deiodinases

Question 4

7 Steps of Thyroid Hormone Synthesis

Answer 4

1. TSH binding to receptor on surface of follicle cell
2. I- cotransported with Na+ across basolateral memb
3. I- moves into lumen of follicle
4. I- oxidised to Iodine
5. Iodine attaches to rings of Tyrosines w Thyroglobulin
6. Thyroglobulin containing T3 and T4 move back into the follicle cells
7. Lysosomes release T3 and T4 from Thyroglobulin -> T3 and T4 get secreted

Question 5

Actions of Thyroid hormone

Answer 5

1. T4 converted to T3 by deiodinases
2. Requires MCT8 & MCT10 to transport T4 and T3 across the plasma membrane
3. Thyroid hormone receptor present in nuclei of mast cells
4. T3 activates Transcription and Translation

Question 6

Effects of Thyroid Hormone on the body

Answer 6

Question 7

Metabolic actions of thyroid hormone

Answer 7

Question 8

Cardiovascular actions of thyroid hormone

Answer 8