mechanism of tanning. skin pigmentation. cross-section of the human skin

age anatomy and beauty biological body brown burn cancer care cell color cream crosssection damage dark dermis diagram educational epidermis for graphic hair health healthy human illustration infographic layer light lotion mechanism medical medicine melanin melanocyte melanocytes melanogenesis melanoma pheomelanin pigment pigmentation process production protect protection protector radiation rays science skin spot structure summer sun sunblock sunburn sunscreen suntan tan tanning turnover ultraviolet use uva uvb vector vitiligo