So we have a negative feedback mechanism that basically helps us control the levels of T three and T four in our body. So basically, if we have a very low level of T three and T four, that will basically cause the hypothalamus to release TRH, which will cause the anterior pituitary gland to release TSH, which will go on and cause the thyroid to release these two hormones. But over time, as the concentration in the blood plasma of T three and T four increases, that will basically affect these two structures via a negative feedback loop, it will cause it will inhibit them from releasing these hormones. And so the T three T four levels over time will basically stabilize. Now, let's move on to the final type of hormone released by the thyroid gland known as calcitonin. Now, we know that the Follicular cells release and produce T three and T four.