Question

What is the reason for the protrusion of the eyeball in Grave’s disease?

Answer 1

Hint: Hormones are chemical messengers, synthesized by endocrine glands. The thyroid is an endocrine gland situated at the root of the neck on either side of the trachea.

Complete step by step answer:
Complete Solution: The thyroid gland secretes three hormones:
1. Tetraiodothyronine or T4 (thyroxine)
2. Tri-iodothyronine or T3
3. Calcitonin.
T4 is otherwise known as thyroxine and it forms about 90% of the total secretion, whereas T3 is only 9% to 10%. In the target cells (particularly cells of the liver, muscle, and kidney), most of the T4 is deiodinated to form T3. So, the true intracellular hormone is T3, rather than T4. T3 has got a high binding affinity for the thyroid hormone receptor.
Thyroid hormones have two major effects on the body: I. To increase basal metabolic rate II. To stimulate growth in children.
Increased secretion of thyroid hormones is called hyperthyroidism. Graves’ disease is an autoimmune disease and it is caused by hyperthyroidism. Exophthalmos is one of the symptoms of hyperthyroidism leading to grave’s disease. The protrusion of eyeballs is called exophthalmos. Exophthalmos in hyperthyroidism is due to the edematous swelling of retro-orbital tissues and degenerative changes in the extraocular muscles.
Therefore, the protrusion of the eyeball in grave’s disease is due to the swelling of tissues behind the eye (retro-orbital).

Note: Decreased secretion of thyroid hormones is called hypothyroidism. Hypothyroidism leads to myxedema in adults and cretinism in children.