The human body has numerous glands that release hormones, useful chemicals, that are required in various body processes. The manufacturing of these hormones is critical as they influence various biological processes in our body. For instance, the thyroid gland secretes two hormones thyroxine (T4) and triiodothyronine (T3) that chiefly 'keep an eye' on the metabolic rate of our body. Besides regulating metabolism, these thyroid hormones also assist in maintaining body temperature.