And that basically means it's water soluble. It can easily dissolve and travel inside our blood, and it binds on to receptor proteins on the plasma membrane of the target cell. Now, in the case of T three and T four, their release is controlled by the hypothalamus and by the anterior pituitary gland. But the calcitonin is controlled by the levels of calcium inside our blood. So if the levels of calcium in the blood is very high, calcitonin will be released by our thyroid gland into the blood. And what the calciotonal basically do is it will try to decrease the level of calcium in the blood by three methods.