Conclusion of a two-part column
Hair is strong
Hair is remarkably indestructible. It decays very, very slowly over time and is resistant to many chemicals. Hair is composed of the protein keratin. In fact, many unearthed mummies still have hair intact!
Most people have about 100,000 hair follicles, but blondes have many more follicles. Blondes can have in excess of 140,000 hair follicles. Redheads have the least with nearly 85,000 hair follicles. Shockingly, our nose hairs can grow up to six feet in length in a lifetime. Only the palms, soles of our feet, and lips do not have hair follicles.
Our stomachs are vital parts of our immune system
The easiest and most common way for germs to enter our body is in and on the food we eat. That means bacteria, fungus and viruses have a direct route into our bodies. Fortunately, our stomachs produce a potent acid known as gastric acid.
This acid helps us to break down food, but it also dismantles the infectious germs that enter our bodies. Gastric acid is so powerful that it can actually dissolve metal. Fortunately, our stomach has a specially designed protective coating to protect us from our own gastric acid.
Humans shrink throughout the day
Our spine has 33 bones. In between these bones are cushion pads made of cartilage. When we sleep, these cushions absorb water and nutrients and expand. These cushions protect the vertebral bones of our spine from the normal wear and tear of moving through life and allow our backs to be very flexible.
During the day, as we stand and walk around, gravity puts pressure on these cushions, and they lose water and become smaller. As a result, most humans, after a long day, are about half an inch shorter than they are when they wake up in the morning with fully plumped-up cartilaginous cushions in our spines. In fact, most astronauts gain one or two inches in height after an extended period in space without the effects of gravity!
Dimples are cute
Humans can have dimples on their cheeks and, on many, also on the lower back. Michelangelo first described these dimples, commonly seen on both sides of the very lower back and called them “dimples of Venus.”
It is a genetic variant of little effect, caused by a shortened ligament that connects the bones of the hip to the skin. Men can have them, too, but they are far less common than in women. In men, Michelangelo called them “dimples of Apollo.”
In many cultures these dimples are considered aesthetically pleasing and attractive and, yes, there are even cosmetic surgical procedures designed to create the dimples on people who lack them, both on the cheeks and on the lower back!
Skin is cool
Skin is the largest organ of the body. Our skin constitutes approximately 15 percent of our total body weight. If our skin were laid out, it would cover about 20 square feet.
The color of our skin and eyes is from a pigment called melanin. Melanin is produced by a special cell called a melanocyte. No matter what skin color you have, or what eye color you have, everyone has about the same number of melanocytes in their body.
The difference in skin color is determined only by the amount of melanin these cells produce. Melanin has the fantastic and essential property of being able to absorb ultraviolet sun rays.
Melanin acts as an umbrella for your skin, and scientists have discovered the difference in skin color is not really a racial characteristic, but a function of how close a group lives to the equator, where the ultraviolet radiation is the strongest.
Your skin is renewed and replaced every 28 days. A significant amount (up to 75 percent) of the dust in your house is actually dead skin cells. Skin cells die and shed at the rate of over 40,000 cells per minute.
This means in an average year a human can shed over 10 pounds of dead skin cells. Scientists estimate that the atmosphere of the world contains over 1 billion pounds of dead human skin in the form of dust.
There are skin mites that live on our skin and also feed on these dead skin cells. In fact, there are over one million skin mites residing in and on everyone’s pillows and bed linens.
Your skin is remarkably waterproof. Think about it: When you jump into a pool or take a bath, you don’t dissolve like placing a piece of bread into a bowl of water. Keratin is the unique skin cell protein that makes skin waterproof.
The skin contains over 10 miles of blood vessels. Goosebumps are really an evolutionary process where particular muscle cells in the skin pull on hairs to make them stand up, giving the upper layers of skin a bit more insulation to preserve heat and warmth. Goose bumps become activated with cold, fear and sexual arousal.
Our skin is host to millions of bacteria, willingly, and these friendly bacteria provide our skin with protection and essential chemicals and nutrients. We have over 14 different types of fungi living on our feet at any one time, and over 1,000 different species of bacteria living on our skin at any one time.
In fact, one square inch of skin contains over 25 million bacteria! We have more bacteria cells in each of our bodies than there are people on earth!
The skin is a source of vitamin D. When the sun hits our skin, vitamin D is produced. Doctors now realize that the amount of sun needed to create the vitamin D required for good health is relatively low, so this is no excuse for tanning. In fact, the best way to obtain vitamin D is through food such as oily fish, like tuna and halibut, enriched dairy products like milk and cheese, and through daily vitamins.
As you can see, our bodies are indeed amazing!
Charles E. Crutchfield III, MD is a board certified dermatologist and Clinical Professor of Dermatology at the University of Minnesota Medical School. He also has a private practice in Eagan, MN. He received his M.D. and Master’s Degree in Molecular Biology and Genomics from the Mayo Clinic. He has been selected as one of the top 10 dermatologists in the United States by Black Enterprise magazine. Dr. Crutchfield was recognized by Minnesota Medicine as one of the 100 Most Influential Healthcare Leaders in Minnesota. He is the team dermatologist for the Minnesota Twins, Vikings, Timberwolves, Wild and Lynx. Dr. Crutchfield is an active member of both the American and National Medical Associations.