All about the skin you’re in

Conclusion of a two-part column

crutchfieldsquareAlthough one would not normally think of it, skin is a key player in a strong immune system. It forms a tight, waterproof barrier to the surrounding environment and also blocks any germs trying to get inside.


(Photo courtesy of Dr. Crutchfield)
(Photo courtesy of Dr. Crutchfield)

There is a coating on the surface of the skin called the “acid mantle” made up of special skin oils and perspiration. This acid mantle makes the skin a hostile environment for many harmful germs and even contains a protein (defensing) that can pierce holes in undesirable bacteria.

Perspiration is another miracle of skin. It helps to eliminate unwanted waste from the body, but more importantly, it cools the body, enabling exercise and movement, via temperature regulation.

The nerves in our skin keep us fully informed about the world around us by detecting all forms of touch and pain.


Wound healing

Because an intact skin barrier is vital to life, any injury or wound to the skin is rapidly repaired.

Special skin cells called fibroblasts detect the injury and spread out of the site and produce collagen, a protein that fills in cuts permanently. Most scars are composed of collagen.

Sometimes the body produces too much collagen and a keloid scar is formed. If the wound is deep, the fibroblasts produce special proteins (cytokines) that cause the injured tissue to repair itself.

Most cuts look good at about two to four weeks, but in reality scars are changing and improving for one to one-and-a-half years! The skin’s ability to repair itself is both miraculous and so important for the maintenance of life.

Think about it: With a hole in the skin, deadly bacteria, fungi and viruses can come in, or vital body fluids can leak out, both situations unacceptable. Because of the skin’s ability to quickly repair itself, life as we know it is possible.


Skin facts 

Most people, under normal circumstances, lose about two cups of of liquid via perspiration every day. That number goes up dramatically with vigorous exercise.

Most people will shed 40-50 pounds of skin cells over a lifetime!


Sunlight: good or bad?

Sunlight is, in general, good for you. It keeps your normal daily 24-hour cycle working (circadian rhythm), fights depression, and helps the skin to make Vitamin D, a component of strong bones.

Unfortunately, sunlight can also be bad for you. Ultraviolet radiation can damage the DNA in your skin cells, which can lead to skin cancer. The deadliest form of skin cancer, melanoma, kills about 100,000 people in the U.S. per year.

The good news is that, if caught early, melanoma can be treated. It is the type of cancer President Jimmy Carter announced that he has.

I recommend my patients enjoy the sun, but be sun smart and sun protect. Use a sunscreen with an SPF of 30 with UVA protection. Apply 30 minutes before sun exposure and reapply every one or two hours, and more so if either actively perspiring or swimming. I say it is smart to use sun protective clothing whenever possible. has some great stuff as far as protective clothing.

I have written a children’s book on sun protection called “Little Charles Hits a Home Run for Sun Safety,” available on

I tell patients if they notice a mole changing in any way, size, color, shape or elevation, or if a spot bleeds and does not heal on its own in three weeks, they should bring it to the attention of their doctor or dermatologist.

Having healthy skin is a key component to having good health.


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 has been selected as one of the top 10 dermatologists in the U.S. by Black Enterprise magazine and one of the top 21 African American physicians in the U.S. by the Atlanta Post. Dr. Crutchfield is an active member of the Minnesota Association of Black Physicians,