The thyroid gland works by using iodine and other components to produce thyroid hormones in the follicular epithelial cells, according to PubMed Health. The thyroid produces triiodothyronine, or T3, and tetraiodothyronine, or T4, in this manner.
The thyroid stores small droplets of T3 and T4 in the follicles, which are located in the individual lobules of the thyroid gland, as stated by PubMed Health. Some of the T3 and T4 hormones attach to carrier proteins in blood. The proteins release the T3 and T4 when the body needs the hormones. C-cells in the thyroid produce a third hormone, calcitonin, which is used for calcium and bone metabolism.
T3 and T4 increase the body's basal metabolic rate, PubMed Health explains. This increases the body temperature and pulse and uses more food energy. It also promotes brain maturation and growth in children. Another result of increased basil metabolic rate is faster reflexes and increased attention.
Hyperthyroidism occurs when the body produces too much of the T3 and T4 hormones, according to PubMed Health. Some symptoms of hyperthyroidism are hot flashes, hair loss, weight loss, insomnia and hyperactivity. When the thyroid produces too little of the hormones, it is called hypothyroidism. Tiredness, cold sensitivity, dry skin, constipation and tiredness are some symptoms of hypothyroidism.