Reprinted from the ACJ - February, 1996
Pop quiz! Name the largest organ in your body. You have 10 seconds. The "Jeopardy" music is playing. Time's running out. I guessed the answer in time, but just by the skin of my teeth. It's no skin off of my nose if you weren't able to come up with the answer, although even some of the skinflints in our accounting department knew the skinny.
Got it? That's right. The largest organ in our body is the … liver. OK, what's the second largest? Take any approach you like. There is more than one way to skin a cat. The correct answer is the skin.
Our skin is not just a Baggie, designed to keep us from spilling all over the floor. In reality it is a vital organ used by our body to protect, regulate and cleanse, as well as keep us in a visually pleasing package.
We often take our skin for granted. Just look at the condition of your hands. You wouldn't let your pancreas get all nicked, chapped, scraped or sunburned like that, would you? As simple as it appears on the surface, the skin is made up of multiple layers, continually regenerating itself. It houses blood vessels, oil glands, sweat glands, lymph nodes, hair and nerves more sensitive than anywhere else on your body.
FRONT LINE OF DEFENSE
The skin can sense temperature and touch. It regulates the heat lost by your body and is constantly exchanging gases and chemicals with our surroundings. The skin acts as front line defense against the nasty chemicals and abusive behavior we subject it to in the shop and at home.
As we have discussed before, the chemicals we use every day can enter our body via three routes of entry; inhalation, ingestion and skin absorption. The skin is subjected to far and away the greatest amount of contact with harmful agents, but is the least likely route by which those agents enter our body. Like an offensive lineman protecting the quarterback, the skin takes all the scrapes, burns and bruises.
The skin is made up of three layers: epidermis, dermis and subcutaneous fat layer. The epidermis and dermis do most of the protective work. In addition, those two layers are responsible for regulating chemical and heat exchange. The subcutaneous fat layer stores fat and gives us reason to exercise.
AN IMPERMEABLE COATING
The epidermis is a thin layer of dead cells covering a thinner layer of live cells. These dead cells provide an almost impermeable coating for our bodies. Inorganic chemicals such as salt, hydrochloric acid, caustic and zinc chloride are not absorbed by the skin, though they do affect it. Some organic substances such as light mineral oils do penetrate into the skin. Other organics do not.
It is the surface reactions more than the absorption that damages our skin. Physical agents (that's the fancy name for hammers, screwdrivers and the sharp corner of a car hood) cause cuts, bruises and burns. Chemicals may burn our skin, but they can also pull vital fluids out, causing injury.
The damage caused by physical agents is obvious. The skin is cut or abraded and we bleed or get blisters. Chemicals such as acids and solvents will react with the water or oil in our skin and cause inflammation or a rash.
Why does a cut or burn turn red, swell, feel hot or sting like the devil? Because we have not only damaged the epidermis, but have injured the underlying dermis layer as well. So blood vessels swell to bring blood cells to the area to start the healing process. That causes redness. The increased flow of blood warms the area. Clotting agents in the blood seal off the area so that no fluids can escape, thus the area swells. This increased pressure of accumulating fluids impacts on the nerve cells not already damaged by the injury, causing pain.
WHY SKIN OIL IS IMPORTANT
OK, that explains what happens when you hit your thumb with a hammer, but what about the dry, chapped skin we sometimes have to cope with? Certain solvents like gas, parts cleaners and even hand and dish soap do their work by grabbing onto and pulling oily, greasy substances away with them. This is true of the oil and fatty substances in our skin. These oils and fats are responsible for softening our skin.
If these oils are removed, the skin is less pliable and scales form, or worse yet the skin splits instead of stretching. This results in what we call dry, chapped skin. Cold weather constricts, and thus reduces the ability of, our oil glands to produce the normal amounts of oil needed. This reduction in oil on our skin enhances the drying effect of solvents and soaps, so we see more of a chapped skin problem in the wintertime.
Sometimes our skin will produce its own chemicals to counteract or neutralize an invading substance. The chemicals produced are called histamines. These histamines are specific to certain irritants/allergens and our body must learn to produce them in response to exposure.
BODY DOESN'T FORGET
Once our body learns it doesn't forget. The next time our skin sees the same irritant our body remembers and reacts. If it overreacts, we say we are sensitized to the allergen. A good example is poison ivy. Those of us who have extreme reactions to even a small dose of ivy are said to be allergic or sensitized to the material exposure.
AVOIDING SKIN DAMAGE
In contrast to the complexity of how physical and chemical agents interact with our skin, prevention of injury is almost schoolboy simple. There are four methods to prevent damage to our skin:
Number one is avoidance. Don't use anything irritating or allow it to touch our skin.
More pertinent to those of us who work with our hands is protection. Use gloves, creams, aprons, face shields, etc. to prevent contact with harmful substances.
A third way to protect the skin is by neutralization of the offensive substance after it contacts the skin. This may sound good in theory, but in practice it is not too feasible. Don't try to neutralize an acid burn by dunking your hands in the boilout tank. You will just end up with two burns instead of one.
The last suggestion for protection of our skin is substituting less irritating products for the ones we now use. Some of the substances we use need to be strong to work, but use common sense. Don't wash your hands in gasoline if water will do the trick.
I realize that skin health may be a dry subject. I may be a little flaky for spending so much time on it. But it is a concept we all should nail down. I hope the pop quiz didn't get under your skin. Don't be offended if you guessed that Wurlitzer was the largest organ. In the repair business, it is best to have a thick skin.
The above article was written by David M. Brown, Chief Engineer of Johnson Manufacturing Company, Inc. and is published by JOHNSON with the expressed approval of the National Automotive Radiator Service Association and the Automotive Cooling Journal. Other reproduction or distribution of this information is forbidden without the written consent of JOHNSON and NARSA/ACJ. All rights reserved.
JOHNSON MANUFACTURING COMPANY
114 Lost Grove Road / PO Box 96 / Princeton, Iowa 52768-0096
Phone 563-289-5123 or Fax 563-289-3825