Local Erythema- reddening of the skin due to increased activity of the blood vessels
Thickening of the skin- UV has a stimulating effect on the cell-producing layer of the epidermis, causing thickening of the skin. This acts as a protection against further irritation of UV light.
Desquamation- UV accelerates the skins normal shedding process. Amount of peeling varies with the strength of the erythema.
Pigmentation- Wavelengths between 2.80-3.30nm, absorbed deep in the epidermis, initiates a chemical reaction. The amino acid tyrosine is converted to melanin. This gives the skin a bronzed appearance. The pigmentation acts as a filter and provides protection against further dosages of UV light.
Production of Vitamin D
Gives a general tonic effect
Effects of UVA Rays- Penetrate more deeply than UVB rays- cause destruction of collagen and elastin fibres in the dermis thus accelerating wrinkles and ageing.
Effects of UVB Rays- Responsible for main erythema production. Most damaging, burning rays.
Effected of UVC Rays- Most of UVC rays produced by the sun are absorbed by the atmosphere and do not reach the skin. UVC rays are described as biotic- harmful to living things.
The skin loses its natural ability to absorb and retain sufficient water causing superficial dehydration.
Decline in the cholesterol content of the skin- influences the amount of sub dermal fat and contributes to a withered look.
Regeneration of the epidermis is reduced and the skin looks thin.