bjones
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A very scientific explanation of why our skin wrinkles is provided by dermatologists. The outer layer of our skin, the epidermis, is made of special cells called keratinocytes. Keratinocytes are largely composed of the protein, keratin. Keratinocytes reproduce quickly in the lower region of the epidermis and push up the older cells. The older cells begin to die about half-way to the surface of the skin. As the cells die, the nucleus disappears leaving behind layers of the cell membrane, made out of lipids, and the inside of the cells, which contain the keratin. Since the membranes are made out of lipids, they resist water, but keratin absorbs water rapidly.
When we are in the bath, or anytime we are exposed to water for a long period, the keratin in our skin begins to absorb the water. The surface area of the outermost part of the epidermis increases, but the innermost layer, where the cells are still intact, doesn’t absorb water and stays the same size. Since the outer layers and inner layers are still attached, the outer layers begin to bunch up around the inner layers. This is what causes the wrinkles. To illustrate this, hold a piece of fabric tightly around your fist. It is relatively smooth. Now, pull some of the fabric up and away, loosening it from your fist. As you increase the surface area of the fabric, it begins to wrinkle.
Why this happens on our fingers and toes but not on other parts of our body is because our fingers and toes have the thickest epidermis. The thicker the epidermis, the more keratin is available to absorb water. Where the epidermis is thin, the surface area doesn’t increase enough to cause wrinkles.
 Posted 5370 day ago
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