Which of the following best describes the T4-binding substance in the blood and the type of cellular receptor for T4 in the peripheral tissues? In a healthy person, the thyroid gland produces and secretes thyroxine (T4), maintaining metabolism.
The correct answer to this question is C. T4, known as thyroxine, is carried by TBG, which stands for thyroxine-binding gloubin. TBG is what binds thyroid hormones in circulation. It is also a transport protein, which carries T4 into the bloodstream. T4 is partially composed of iodine.
T4 can have a decrease in production, when there is a deficiency of iodine. It is a major thyroid hormone and has a longer life cycle than T3. Like all thyroid hormones, T4 has many functions, including increasing metabolism, generating heat, regulating bone growth, and helping the development of cells in the body.