Although the skin is less complex than most other organs, it covers the entire body and accounts for about 7 percent of our total weight, making it the largest organ. The epidermis is the outer and visible layer of the skin. This creates a protective barrier from ultraviolet light reaching deeper, more sensitive layers of the skin. Thus the whole tanning process is the body's own natural defense against sunburn and skin damage. Melanin, the most important pigment, is made from an amino acid called tyrosine.
Melanin ranges in color from yellow to red to brown to black.
Its production depends on an enzyme in melanocytes called tyrosinase. Carotene is a yellow to orange pigment resulting from certain plant products, such as carrots. The pink tone of Caucasian skin reflects the crimson color of oxygenated hemoglobin in the capillaries of the dermis, or middle layer of skin. Ultraviolet light, whether produced by the sun or an indoor tanning unit, consists of two main components. Outdoor tanning does not give you this control, because the sun emits the entire spectrum of ultraviolet light, including the most intense rays that burn you more quickly.