The Functions and Structure of Skin
Skin care consumes billions of dollars annually. The effects of growing old are increasingly clear to an aging population. Hundreds of products for skin care are on the market, each promising to stop or reverse the aging process. There are products for moisturizing, cleaning, lubricating and protecting the skin. The best of these products are based on a solid, scientific understanding of the nature of skin.
With all this investment and concern, few people understand the nature of skin itself. This amazing organ serves many functions in keeping the human body running efficiently. Aside from providing a barrier for our internal organs, the skin regulates the body's temperature, transmits the sensations that give meaning to touch and feel, and stores much of the body's fat and moisture.
Skin consists of three bonded layers, each layer much different from the other. These layers include the:
Epidermis - The top layer of skin consists primarily of keratinocytes - cells that contain the fiber Keratin.
Dermis - The middle layer is the most active. It contains the sweat glands, nerves, blood vessels and hair follicles
Subcutis - The inner, third layer completes that barrier effect of the skin. It is where the body stores the lipids that constitute body fat. Its thickness allows it to serve as something of a shock absorber for the body.
The epidermis is, of course, the layer that we see. This layer contains melanocytes, the cells that determine skin color. The epidermis is itself quite ingenious in its structure. It also has three layers. The inner part of the epidermis consists of basal cells that constantly produce new keratinocytes. These new cells move to the second level as they mature. These cells in turn move to the surface to replace the dead cells that are constantly shed. This process means we have a new layer of epidermis every 4 to 5 weeks.
It surprises many people to realize that the outer surface is dead keratin cells. This is the same for our hair and nails. As the keratinocytes mature, they fill with keratin fibers and become inert.
The name keratin comes from the Greek meaning horn. The outer layer of the epidermis is the stratum corneum or horny layer. It allows the skin on soles of the feet and other areas to form an even stronger protective barrier.
How This Structure Affects Skin Care
While discussing the structure of skin is boring to some, it is vital to understand the role of skin care. Exfoliating facial wipes and products help to remove the outer layer of dead keratin cells without damaging the healthy second layer of mature cells. It is this layer that gives skin a healthy or sallow appearance.
Moisturizing creams and similar products have value because they help protect these layers of cells. The keratin cells are up to 15% water and require constant replenishment. Skin care for sensitive skin deals with this second layer of the epidermis and removes the dead surface cells.
Keratin is an amazing substance that determines how we see our two most visible grooming concerns, our hair and skin.