And we also actually have a negative feedback mechanism as we'll see in just a moment. So let's begin by discussing the triidothyrene hormone T three and the thyroxine hormone, the T four hormone. Now, inside our thyroid gland, we have a type of cell known as our follicular cell. And this follicular cell is responsible for synthesizing and releasing T three and T four hormones. Now, both T three and T four are produced using our tyrosine amino acid. T three simply means we have three eyed ions, three eyed atoms.