Human aging is the accumulation of changes in an organism or object over time. It refers to a multidimensional process of physical, psychological, and social change. And aging skin is referred as physical or biological aging. Aging skin can cause by 2 factors, the intrinsic factor and extrinsic factor. Intrinsic aging, also known as the natural aging process, is a continuous process whereas extrinsic factor is aging process caused by external factor. The aging skin process is explained by genetic, metabolic, biochemical, and evolutionary theories.
Causes of Aging Skin
Intrinsic Aging
DNA Damage Theories
Every cell division the telomeres at the ends of chromosome are shortened by approximately 65 base-pairs. This contributes to accumulated damage to DNA which in turn inhibits cells' ability to function and express the appropriate genes. This leads to cell death and overall aging of human.
- DNA Damage/Repair Theory
- Free Radical/Oxidation Theory
- Mitochondrial DNA Theory
- Radiation Theory
Built-In Breakdown Theories
Aging is a direct consequence of genetic programming. The causes for aging are directly built into the genome and cellular structure, as a sort of molecular clock.
- Disposable Soma Theory
- Genetic Theory
- Immunological Theory
- Telomere Theory
Extrinsic Factor
Environmental Stress Factor (EFS)The skin reacts to these environmental stress factors by producing free radicals. Research has shown that free radicals are responsible for premature aging and certain forms of cancer. The body's natural defense mechanisms, which include antioxidants, fight to destroy free radicals before they can cause cellular inflammation that leads to permanent damage. If excessive numbers of free radicals are produced they begin to overwhelm the body's natural defense mechanisms and the extensive cellular injury is no longer able to adequately heal. In the skin, this type of permanent injury goes on to form microscopic scars. As these tiny scars proliferate, a visible wrinkle forms and thus presents as an early visible sign of premature aging.
Sun ExposureMuch of the aging caused by external factors is due to sun exposure. The accumulation of daily sun exposure leads to premature aging of the skin and hastens the other skin aging causes such as intrinsic aging. Usually, signs of sun aging appear in the 20s for people in areas with a lot of sunshine. The sun can cause freckles, ages spots, spider veins or broken capillaries on the face (telangiectasis), rough and leathery skin, fine wrinkles, loose skin, irregular skin pigmentation, actinic keratoses (thick, warty, rough, reddish, growths), and skin cancer.
Aging caused by the sun (photo-aging), depends on the skin colour of the individual with fair-skinned people being more vulnerable than dark-skinned people. Dark-skinned individuals are usually only susceptible to wrinkles and skin mottling as a result of sun exposure.
The history of sun exposure and especially overexposure is also an important cause of skin aging. Damage caused by the sun is cumulative. Ultraviolet light acts to break down elastin and collagen in the skin and interferes with the production of new collagen.
Repetitive Facial ExpressionsRepetitive facial expressions like squinting or facial exercises lead to fine lines and wrinkles. In fact, it is strongly believed that facial exercises cause more lines and wrinkles and are not an effective wrinkle prevention treatment. This is because grooves form beneath the skin surface when the facial muscles are used because of breakdown of the collagen. With aging, the ability of the skin to spring back decreases and the grooves develop into permanent lines and wrinkles. Frown lines (those lines between the eyebrows) and crow's feet (the lines that stem from the corners of the eyes) are common examples of this problem.
GravityGravity is one of the skin aging causes that often goes unnoticed. The pull of the earth's gravity (although we don't feel it) is responsible for significant changes in our bodies as we age. This is especially the case around age 50 for skin. The skin has lost some of its elasticity and the skin begins to sag in facial areas and other parts of the body.
Smoking 
Smoking is one of the more important skin aging causes that often gets overlooked. Smoking causes biochemical changes in the body that make skin age quicker than it should. Studies have shown that individuals smoking more than 10 cigarettes per day for more than 10 years are more likely to develop deep wrinkles and leathery skin. Yellowy skin on the overall body and on the fingers is another side effect of long-term smoking. The repetitive action of holding a cigarette between the lips leads to significant facial lines and wrinkles around the lip and chin areas.
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