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xrose木虫 (正式写手)
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Why does skin wrinkle with age?
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Normal healthy skin has a nice epidermis with a smooth cornified, or outer, layer that acts as a good barrier to water and environmental injury. Skin color and tone is even and unblemished. Components such as collagen (which provides skin firmness), elastin (which supplies skin elasticity and rebound) and glycosaminoglycans or GAGs (which keep the skin hydrated) are all abundant. It is interesting to note that under a microscope a biopsy of a wrinkle exhibits no telltale signs that reveal it to be a wrinkle. So what causes the skin to look wrinkled? It is probably a multi-factorial process of intrinsic aging and extrinsic aging. Intrinsic aging is the natural aging process that takes place over the years regardless of outside influences. After the age of 20, a person produces about 1 percent less collagen in the skin each year. As a result, the skin becomes thinner and more fragile with age. There is also diminished functioning of the sweat and oil glands, less elastin production, and less GAG formation. Wrinkle formation as a result of intrinsic aging is inevitable, but it will always be slight. Extrinsic aging occurs in addition to intrinsic aging as a result of sun and environmental damage (tobacco use and exposure to pollution, for example). Extrinsic aging shows up as thickening of the cornified layer, precancerous changes such as lesions called actinic keratosis, skin cancer (including basal cell carcinoma, squamous cell carcinoma, lentigo maligna melanoma), freckle and sun spot formation, and exaggerated loss of collagen, elastin, and GAGs. Alone or in concert, these processes give the skin the appearance of roughness, uneven tone, brown patches, thin skin and deep wrinkles. Prevention is key to minimizing wrinkles. The most important thing is to take care of your skin before all these changes start to take place. Sun protection against both UVA and UVB rays is critical 365 days a year using an SPF of at least 35: I prefer zinc- or titanium-based products. After the age of 25 I recommend using Retin-A (a vitamin A derivative that uses the generic name tretinoin) as an antiaging cream. It is a prescription agent that has been used for more than 30 years with a safe track record and excellent results. In the first two or three months patients may experience redness, peeling and flaking, but should then noticed a marked improvement. Over time tretinoin improves fine lines, the appearance of pores, precancerous changes, and brown spots. If tretinoin treatment is not enough, then medium depth chemical peels and some non-invasive lasers can help build collagen and thus improve the skin's appearance. |
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2楼2005-09-28 10:03:50
