UV Rays and Your Skin
When you start to notice your skin tanning or burning, what is actually happening is a natural reaction. The melanin in your melanocytes is stimulated by the Ultraviolet, or UV rays in the sun beams.
The reason this happens is because the melanin is serving as protector for the rest of your cells. Melanin actually absorbs harmful UV radiation to prevent it from affecting other cells in your body. In Caucasian skin, the production of melanin takes a significant amount of time. Melanin levels typically don't reach the protective level until exposure for 4-7 days. In some other races, the melanin levels are far higher, and pigment is present in the skin all the time. This is why the instances of skin cancer are far lower in certain races than in others.
Your melanin and melanocyte production is controlled by the release of MSH - Melanocyte Stimulation Hormone. MSH release is triggered by the Pituitary gland in your brain. When your brain recognizes an increase in natural sunlight MSH is released to produce melanocytes in the skin, which in turn, recognize the presence of UV radiation, and produce melanin to absorb the rays.
The Ultraviolet radiation in sunlight can be broken down into three parts:
- UVA (also called 'blacklight' - responsible for a tan)
- UVB (the harmful portion of UV rays - responsible for burning)
- UVC (filtered out by atmosphere and never reaches us)
90% of the UV radiation we are exposed to is UVA. The other 10% is the UVB which contains the harmful agents known to cause burning, skin wrinkles, and cancer.