Unless wounded or suffering a rash or whatever, I venture to suggest that people mostly attend to how skin looks. It’s only logical, given that it’s exposed to public view—more or less, depending on culture, sex, age, season, and occasion!
Putting Your Best Face Forward
The good news is this: skin is constantly renewing itself, shedding dead cells and producing new ones. On average, we lose about 30,000 to 40,000 skin cells per minute. You may not see the dead, dull skin flaking off your face and body, but it is, and it contributes significantly to household dust!
It takes about a month for newly formed skin cells to make their way to the surface. The bad news is that renewal takes longer with age: turnover can take as much as six to eight weeks in someone in their 60s or 70s.
A buildup of dead skin cells can make your complexion appear duller and drier.
Like your body’s overall metabolism, the skin’s metabolic processes also lag with age and exposure to environmental aggressors.
The skin’s metabolism controls the production and breakdown of collagen and elastin. It also affects how well your skin renews its cells, repairs its damage, and even how it responds to topical products you use.
Giving Nature a Helping Hand
You can speed up the process of skin renewal (at any age) with topical products that contains retinoids, which promote new cell growth, or alpha hydroxy acids, including glycolic acid. These loosen up the intercellular glue-like substance that holds skin cells together on the surface, allowing them to slough off sooner. You can find these ingredients in cleansers, serums, lotions, or creams.
An alternative is the judicious use of skin exfoliants. Harsh or excessive exfoliation can cause small tears, which allow water to escape and potential irritants to pass into your skin, making it feel dry and sensitive.
Heads up: the molecules in most cosmetic compounds are too large to be absorbed, so be suspicious of claims about absorption.
Even molecules in some anti-aging skin-care products are too large to pass through skin’s outermost layer.
When the skin’s barrier gets damaged (from UV exposure, harsh cleansers, over-exfoliating, etc.), microscopic tears form.
Sunscreen keeps skin’s surface safe from sunburns and its cells protected from UV damage. My dermatologist recommends a lotion with SPF 35 on the face, every day, year-round, and something stronger for extended exposure, for example when sailing.
The road to healthy, radiant skin is paved with blood vessels. Skin contains 11 miles of blood vessels. Each square inch contains 20 blood vessels.
Gilding the Lily
One’s skin is an expansive canvas. The average adult has 2,800 square inches—about 22 square feet—of skin, and people have painted on it for more than 6,000 years, when ancient Egyptians (both women and men) used makeup to enhance their appearance and display their wealth. Now the beauty industry is a key driver of the U.S. economy, generating approximately $94.36 billion in cosmetics and beauty sales in 2023. Enough said about that.
Over time and around the world, for the sake of appearances, skin has been tattooed, pierced, and scarred, kept pale or tanned vigorously. Standards of beauty vary greatly from culture to culture.
But beyond its ornamental value, skin is incredibly useful!
The Real Skinny on Skin
Next time you step on the scale, remember that skin is the heaviest of all your organs. The average adult body can have 20 pounds of skin alone, making up 10-15% of body weight. That 10-15% is composed of water, oils, fats, nutrients, hair follicles, blood and lymph vessels, collagen, and living and dead cells.
Within one square inch of skin, there are 19 million skin cells of various types, each with its own specific job.
That square inch includes about 60,000 melanocytes, cells that produce melanin pigment, which gives skin its color. All humans have melanocytes (with the exception of some people born with albinism).
The majority of skin cells are keratinocytes. These include basal and squamous cells, the two types from which the most common skin cancers can arise.
Skin Hard at Work
According to the Cleveland Clinic, a square inch of skin also contains 300 sweat glands—for better or worse!
Skin helps regulate body temperature by sweating, but also by dilating blood vessels. Blood vessels bring oxygen and nutrients to your cells, remove waste, and help regulate your skin’s temperature. When the skin gets warm, your blood vessels dilate, allowing heat to escape to the outside air. When it’s cold outside, they constrict, keeping the heat in your skin.
Skin is a sensory organ, each square inch containing 1,000 nerve endings, allowing us to feel touch, temperature, pain, pressure, and vibration.
Skin is also highly reactive to emotional stress. Research has shown that skin inflammations such as eczema, psoriasis, and acne often flare during stressful times.
Stressful situations can also trigger sweating, itching and hives.
Experts have found the connection between stress and skin is bidirectional: stress can exacerbate skin issues, but skin can also send signals to the brain, triggering a stress response.
Skin is the protective barrier against external threats, such as UV rays, bacteria, and infections.
Under the Surface
Skin has a microbiome, with trillions of microorganisms such as bacteria, viruses and fungi that help in fighting infection, controlling inflammation and helping your immune system recognize possible threats. Researchers are working on treatments to manipulate the bacteria on the skin’s surface to treat inflammatory skin conditions such as atopic dermatitis, acne, and diseases including skin cancer.
Researchers have discovered that skin has a circadian rhythm. During daylight hours, skin is in protective mode, trying to shield cells from UV light, free radicals, pollution, etc. Research shows that repair peaks at night. Both temperature and permeability increase at night, making skin more receptive to topical ingredients. Also at night, more water escapes from the skin. So, before bed, it’s prime time to apply moisturizer.
The thickest skin grows on the soles of the feet and palms of the hands, while the thinnest grows on the eyelids.
When exposed to sunlight, skin produces vitamin D, which is essential for bone health.
Your skin can flex. There are tiny muscles within the skin called the arrector pili muscles, located inside your hair follicles. It’s these muscles that make your body hairs stand straight up when you get goosebumps.
Medical Uses of Skin
My guess is that when people sign their organ donor cards, very few are thinking “skin.” Heart, liver, kidney, lungs…sure. In fact, skin is the largest organ in (on?) the human body. And skin donations are sorely needed.
Each year, approximately 58,000 tissue donors provide lifesaving and healing tissue for transplant. A single tissue donor can heal up to 75 lives. That’s why surgeons can perform approximately 2.5 million tissue transplants each year in the U.S.
Three-quarters of skin transplants are used in life-saving circumstances, such as severe burns. Doctors also use skin grafts in various surgeries, including open heart and post-mastectomy breast reconstruction. Experts estimate that another 500,000 patients would have shortened wound-healing time if enough skin were available.
Should you need a skin transplant, the preferred source would be you! Doctors usually take skin from the patient’s back, buttocks, and the backs of the thighs. These are highly effective, successful over 90% of the time. Skin donations from another person (living or dead) or from an animal, such as a pig or a fish, are stop-gap measures, to minimize infection and maximize fluid retention till you are able to repair yourself. “Foreign” skin is nearly always rejected long term.
Bottom Line: The title says it all. Skin is useful as well as ornamental
