2. Prevent microorganism invading. The cuticle has a good barrier to microorganisms. Under normal circumstances, bacteria and viruses can not enter the human body from the skin. When the skin is damaged, the defense ability is destroyed, it is easy to be infected by pathogenic bacteria.In addition, some beneficial fatty acids in skin sebum inhibit the growth of parasitic bacteria.
3.Prevent UV damage. Because the cuticle of the skin reflects most of the sunlight, the epidermis cells have the ability to absorb ultraviolet light, and the melanin particles produced by the melanocytes in the basal layer of the epidermis are the most powerful absorbers of ultraviolet light.