What Exactly is Skin, and How Does It Change?
- Posted on: Jun 12 2018
You probably know that skin is your body’s biggest organ, a flexible sort of “armor” to protect all your other organs. But you may wonder, what exactly is skin?
Your skin has three layers. The outermost layer is the epidermis. It varies in thickness, depending on where it is on your body. Your epidermis is about 0.5 mm thick on your eyelids but about 1.5 mm thick on your palms and the soles of your feet. It contains superficial nerves, and it’s the layer we target with exfoliation and skin resurfacing topicals.
The epidermis itself contains five layers. The innermost layer of the epidermis is the basal layer, which produces pigmentation in the case of tanning, moles, freckles, birthmarks or age spots. Basically, this is the layer most affected by sun damage. The outermost layer is the stratum corneum, which is largely composed of dead cells that are constantly sloughing off. In young adults, these cells are completely replaced about once every month. In older adults, this is a slower process, with a complete cell turnover every month and a half to two months.
This is why we need to exfoliate more frequently as we age—but also, more gently, because our epidermis becomes thinner and more fragile. The epidermis also loses lipids with age, which contributes to dryness and means we need to step up the moisturizing.
Under that, there’s the dermis, the thickest layer of skin. It contains blood vessels and nerves, sweat and oil glands, and hair follicles. Its primary function is to regulate temperature and supply the epidermis with nutrient-rich blood. The dermis is held together by elastin and collagen, so this is the layer we stimulate with “collagen” building treatments, such as microneedling. This is also where we inject most fillers and neurotoxins to prevent and repair signs of aging.
As we age, some of our oil and sweat glands quit working, so it becomes harder to regulate body temperature, which is why elderly adults are more vulnerable to heat stroke and extremely dry, itchy skin. For women, this change happens gradually, beginning after menopause, which means you may need more intensive moisturizers. For men, this process happens later—in the 70’s and 80’s.
Below the dermis, there is the subcutis or subcutaneous layer, a layer of fat that conserves heat around your internal organs and protects your bones and muscles when you get bumped or fall. It also stores fat as an energy source. As we age, this layer grows thinner as well, which means older adults are more prone to bruising and hypothermia.
The takeaway is that aging skin requires special care, both from a health and a cosmetic perspective. Aging adults should moisturize more frequently and make sure they have the right gear for the weather. And if you’re bothered by the cosmetic signs of aging—the lines, less elastic and sagging skin, the dryness and spots of hyper-pigmentation, schedule a consultation with Dr. Adams. The science of skincare and anti-aging has come a long way in a short period, and there are a lot of options, if your outward appearance doesn’t match the way that you feel on the inside.