human skin. of absorbing and reflected uv rays

absorbing anatomy and blocked body burn cancer carcinogen carcinoma care collagen cream damage damaging deep dermis diagram elastin epidermis excessive fibres graphic health healthy human hypodermis illustration into layer layers light lotion medical medicine melanin melanoma not penetrate penetration pigmentation process protect protected protection radiation rays reflected skin structure summer sun sunblock sunburn sunscreen suntan tan tanning the they thus ultraviolet uva uvb