Now, the function of calcitriol is to basically regulate the amount of calcium and phosphate ions found inside our skin. So we need vitamin D to basically regulate the amount of calcium found in our blood, as well as the amount of phosphate ions found inside our blood. And this is why the skin is an endocrine organ. It produces this pre hormone known as our colicalcipheral. Now, the final function, function number seven of the skin, is basically in growth. So we know that as the human grows, as the bone grows and the organ grows, the skin must grow along with everything else inside the human body.