Question

For each item related to thyroid gland activity A–E, select the best option for its functional description from the following list. 

1. The most active form of the thyroid 

2. A disease caused by thyroxine deficiency in hormones. adults. 

3. Protrusion of the eyeballs seen in 

4. A pituitary gland hormone that stimulates patients with thyroid overactivity. the thyroid gland. 

5. A glycoprotein stored in colloid in thyroid gland follicles. 

A. Thyroglobulin. 

B. Triiodothyronine (T₃). 

C. TSH. 

D. Myxedema. 

E. Exophthalmos.

Answer 1

A. Option 5 A glycoprotein stored in colloid in thyroid gland follicles. Thyroglobulin is manufactured in the thyroid follicular cells and is secreted by exocytosis of granules into the colloid for storage. The hormones remain bound to the colloid until they are secreted into blood capillaries. 

B. Option 1 The most active form of the thyroid hormones. T₄, which contains four iodine molecules, is less physiologically active than T₃. 

C. Option 4 A pituitary gland hormone that stimulates the thyroid gland. TSH secretion from the anterior pituitary gland is controlled by the hypothalamic hormone, thyrotropinreleasing hormone (TRF). 

D. Option 2 A disease caused by thyroxine deficiency in adults. A disease characterized by low basal metabolic rate, coarse hair and skin, poor cold tolerance and mental slowness. 

E. Option 3 Protrusion of the eyeballs seen in patients with thyroid overactivity. Due to swelling of the external ocular muscles and other orbital tissues.