Skin ageing occurs primarily inside the skin, resulting in the appearance of externally visible signs. In a society that increasingly favours appearance, the social impact of visible skin ageing may be considerable.
Beyond the normal ageing of the skin tissue (intrinsic factors), many external factors (extrinsic factors) are also involved and accelerate the onset of irreversible damage.
Intrinsic factors of skin ageing or chronological ageing cause damage to all skin tissues. Among others, in the epidermis, renewal of keratinocyte cells slows down; in the dermis, the amount of collagen and elastin decreases as a result of an imbalance between degradation of macromolecules and a general decrease in synthesis metabolism. The dermis and epidermis become thinner, the dermisepidermis junction becomes linear, and wrinkles appear.
Among extrinsic factors, photo-ageing damage is created by continuous exposure or overexposure to the sun’s rays. Overexposure to UVA/UVB/UVC radiation is harmful to the skin. Fortunately, the most dangerous rays, UVC, are blocked by the ozone layer, but UVA and UVB rays reach the skin directly, potentially causing critical damage. UVB is primarily responsible for skin burns and DNA damage (formation of dimers) that can lead to mutations, while UVA rays generate oxidative reactions affecting DNA, proteins and lipids. They also lead to a reduction in the immune defences.
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