Thyroid Eye Disease

Question 1

Where does the Blood Supply for the Thyroid Gland come from?

Answer 1

Arterial Supply is from the Superior Thyroid Artery and the Inferior Thyroid Artery.

Venous Supply drains blood into the Superior, Middle and Inferior Thyroid Veins

Question 2

What are the Steps for Thyroid Hormone Synthesis?

Answer 2

1. TRH (Thyrotropin-releasing hormone) releases from the hypothalamus (specifically the paraventricular nucleus)
2. TRH stimulates thyotropes in Anterior Pituitary Glands to release TSH (Thyroid Stimulating Hormone)
3. TSH travels through the blood stream to the follicular cells of the Pituitary Gland, and with the presence of Iodide creates Thyroglobulin (TGB)
4. Iodide is present in the blood stream and gets into the cells by co transportation with Sodium and ultimately gets separated and isolated by pendrin.
5. TPO (Thyroid Peroxidase) is the enzyme that oxidizes the free Iodide(I-) to Iodine (I2)
6. TPO then undergoes Iodination (placing the I2 onto the amino acid chain made in step 3)
7. Now each section of the amino chain has Iodine molecules attached, we need to couple the Di-Iodo-Thyrosine amino acid (DIT) and Mono-Iodo-Thyrosine (MIT).
   SO DIT+DIT = T4 and DIT+MIT = T3
8. The Thyroglobulin Colloid is now Endocytosed (englufed back into the cell)
9. Lysosomal Enzymes Cleave (cut/seperate) the T3 and T4 out of the TGB
10. The T3 and T4 are exocytosized out of the cell and sent to the target cell.

Question 3

What is the Role and Purpose of T3 and T4

Answer 3

bind to nuclear receptors inside the cells which initiate a transcription of the gene to change the receptor of the target cell.

Basically they control Metabolism.

• Increase basal metabolic rate
  
  • Increase body
    temperature
  • Increase pulse rate
    Break down of food
    storage in the liver and
    muscle
• Enhance sympathetic nervous system activity
  
  • Faster reflexes
    Increased heart rate
    and cardiac output
• Helps in normal growth and development
• CNS development

Question 4

What happens when EXCESS T3 and T4 are created?

Answer 4

An Excess will cause reduction of TSH created through negative feedback of the thyroid hormones, meaning Less T3 and T4 will be made to even out the balance