And that basically helps us protect from bacterial agents. On top of that, the hypodermis, the subcutaneous lay of the skin, contains macrophages that can actually engulf bacterial cells. Now, function number six is that as our endocrine gland. So, remember earlier, I mentioned that the skin actually needs UV radiation. So certain cells in the epidermis of our skin are responsible for using UV radiation, the energy stored in UV radiation, to actually produce something called colic calcipheral. And this is basically an inactive form of vitamin D three.