Write short note - Disorders / Disease of thyroid gland.

Explanation

Location: The thyroid gland is composed of two lobes which are located on either side of the trachea.
Both the lobes are interconnected with a thin flap of connective tissue called Isthmus.
Structure : The thyroid gland is composed of follicles and stromal tissues. Each thyroid follicle is composed of follicular cells, enclosing a cavity.
These follicular cells synthesize two hormones, tetralodothyronine or thyroxine (`T_(4)`) and triiodothyronine (`T_(3)`).
lodine is essential for the normal rate of hormone synthesis in the thyroid.
Deficiency of iodine in our diet results in hypothyroidism and enlargement of the thyroid gland, commonly called goitre.
Symptoms of goitre stunted growth (cretinism), mental retardation, low intelligence quotient, abnormal skin, deaf-dumbness etc. Hypothyroidism during pregnancy causes defective development and maturation of growing body.
In adult women, hypothyroidism may cause menstrual cycle to become irregular.
Due to cancer of the thyroid gland or due to development of nodules of the thyroid glands, the rate of synthesis and secretion of the thyroid hormones is increased to abnormal high levels leading to a condition called hyperthyroidism which adversely affects the body physiology.

Functions :
(i) Thyroid hormones play an important role in the regulation of the Basel Metabolic Rate. (B.M.R.)
(ii) It support the process of Red Blood Cell (RBC) formation.
(iii) Thyroid hormones control the metabolism of carbohydrates, proteins and fats. (iv) Maintenance of water and electrolyte balance is also influenced by thyroid hormones. (v) Thyroid gland also secretes a protein hormone called thyrocalcitonin (TCT). regulates the blood calcium levels.
Exophthalmic goitre is a type of hyperthyroidism. It increases size of thyroid gland. Eye ball come out, there is rise in metabolic rate, decrease in weight etc. It is also called Graves disease.