Since Sam's interest is in cosmetics, I am starting a unit on human skin, the anatomy and physiology of the skin. As we are progressing, I am stressing the importance of the physiology of the skin as regards her main interest. The term cutaneous was introduced as well as the main functions of the skin: immunity, prevention of dehydration, insulation, temperatue regulation and sensation. I discussed and outlined the improtance of each function as we listed them, as well as the evolutionary development of each function. The term pigmentation was developed and discussed in terms of variations among population and the need to incorporate the chemistry of pigmentation into products for cutaneous use. Using a diagram of the skin, we looked at the epidermis, defined the term and viewed the 5 structural layers which comprise this main layer of skin. Keratinization and desquamation were explained.