Now, once the skin produces Cola Calciphral, it travels into our liver, where we basically transform Cola Calcipher into calcidial. And then calcitial travels into our kidneys. And in the kidneys, that calcitial is transformed into the active form of vitamin D, calcitriol. 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.