You: Being Beautiful: The Owner’s Manual to Inner and Outer Beauty. Michael Roizen F.

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      The reason why there are butterfly collectors and not moth collectors? The colors of moths are determined by scales that are shed, so they don’t keep their colors in the box, only in life—just like humans. The colors of a butterfly’s wings are never lost.

      Your Skin: Let’s Flesh a Few Things Out

      Funny, whenever we say something’s skin deep, we mean that it has about as much depth as a puddle. But that’s hardly the case with skin—it’s an amazing and complex organ that extends much deeper than the part we can actually see and touch. Your skin is the biggest and heaviest organ of your body, making up 15 percent of your body weight and covering 12 to 20 square feet. The composition: 70 percent water, 25 percent protein, and less than 5 percent fats. The obvious role of skin is to protect and to package. It protects our blood, organs, and bones from what’s outside, and it also packages our body neatly together so we’re not blobby organisms that leave trails of blood and bits of tissue everywhere we go.

      And skin does more than serve as our anatomical casing. Skin also helps us with healing. How? Touching in that loving way reduces levels of the stress chemical cortisol and increases levels of the feel-good chemical oxytocin. And touching in that special way (massaging and caressing, not the touch of a slugger’s right hand) also stimulates the vagus nerve, which runs up to the brain to improve the health of our whole body.

      So here’s how your skin works. While serving as an obvious barrier to the millions of chemicals and germs that want to invade your body, it also has a big sensory function. Deep in the skin, follicles grow hairs that can sense before your skin is actually touched. Eyelashes, for example, prompt the eyelid (through great nerve connections) to involuntarily close to protect the eye before you even know you’re in danger and to quickly flick off bugs before they bite.

      Besides sprouting up hairs that sense things, your skin lubricates itself with oils we call sebum produced by sebaceous glands and also absorbs certain medications and hormones. But it can also absorb things, such as toxins, that you don’t necessarily want. And ultraviolet light can turn your own skin against itself by creating those much-talked-about damaging free radicals, not to mention changing your DNA (and usually not for the better).

      Like many structures in your body (including your blood vessels), your skin has several components (see Figure 1.1).

      FACTOID

      We can generate as much as a gallon of sweat in two hours, so we don’t have to pant like a dog (dogs don’t sweat). Also, unlike dogs, most of us don’t shed our furry coat, but we do lose nine pounds of skin a year. That’s a lot of dust.

      Epidermis: Serving as the body’s primary barrier against the outside world, the epidermis is less than a millimeter thick. Your skin is your raincoat, keeping your insides dry and letting you swim without swelling. Your epidermis is so well designed that only the right-size molecules can get through. The cool thing about your skin is that it renews itself every six to eight weeks. How? Dead cells from the epidermis continually slough off and are replaced by new ones from below (that’s one major way you get dust in your home—the sloughing off of skin). Your epidermis largely determines how fresh your skin looks—as well as how well it works in terms of absorbing and retaining moisture.

      Dermis: The thickest of your skin layers, the dermis is what actually holds you together.^* It’s your leather. The dermis is made up of cells called fibroblasts, which make collagen and elastin, proteins that give the dermis its strength and allow it to be stretched. Dotting the dermis are hair follicles, sweat glands, and sebaceous glands, which produce the oily sebum that lubricates your skin and hair. This sebum is really a mixed blessing; while it helps keep bacteria under control, it also attracts insects. Finally, the dermis contains tiny blood vessels (to nourish the skin) and lymph nodes (to protect it from toxins). Subcutaneous tissue: This innermost layer is made up primarily of fat and acts as a shock absorber and heat insulator for your body (many mammals, by the way, don’t have this because their fur does the same job).