Give information regarding the location of the thyroid gland and its hormones.

(N/A) 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 the 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,tetraiodothyronine or thyroxine $(T_{4})$ and triiodothyronine $(T_{3})$.
Iodine 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 include stunted growth (cretinism),mental retardation,low intelligence quotient,abnormal skin,deaf-mutism,etc. Hypothyroidism during pregnancy causes defective development and maturation of the growing body.
In adult women,hypothyroidism may cause the menstrual cycle to become irregular.
Due to cancer of the thyroid gland or due to the development of nodules of the thyroid glands,the rate of synthesis and secretion of the thyroid hormones is increased to abnormally high levels,leading to a condition called hyperthyroidism,which adversely affects body physiology.
Functions:
$(i)$ Thyroid hormones play an important role in the regulation of the Basal Metabolic Rate $(BMR)$.
$(ii)$ They 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.
$(v)$ The thyroid gland also secretes a protein hormone called thyrocalcitonin $(TCT)$,which regulates blood calcium levels.