Explanation

The thyroid hormones are calcitonin, thyroxine (T4) and triiodothyronine (T3). Calcitonin helps to make sure that you have the right amount of calcium in your body, so that you have strong bones.

Your thyroid gland uses iodine to make T3 and T4. T3 is called T3 because it contains three iodine units, and, likewise, T4 is so-called because it contains four iodine units.

Thyroid hormones are important because they affect all of your body's cells. They increase the rate of cell metabolism, which makes them grow and divide, and also makes major body functions go a little faster.

Most of the organs and tissues in your body are affected by thyroid hormones, including your heart, skin, digestive system and nervous system. They help to develop your brain, bones and muscles, and also help to keep your body at the right temperature and help it use energy.

Your hypothalamus, pituitary gland and thyroid gland work together to make sure you have the right amount of thyroid hormone in your blood. When there is not enough, your hypothalamus releases a hormone called thyroid releasing hormone to tell your pituitary gland to release thyroid stimulating hormone.