It protects the organs of the body. Think about this..... Your bones are arranged so that each organ is protected. Each bone is like a border so that your organs are not exposed. If you didn't have bone then, if you got hurt then your vital organs could get hurt. It doesn't eliminate wastes from the body because that's the excretory system. It doesn't produce facial expressions since that is the nervous system ( heat is also controlled by the nervous system).