MEDICALEXAMINER
TM
HEALTH • MEDICINE • WELLNESS • HEALTH • MEDICINE • WELLNESS • HEALTH • MEDICINE • WELLNESS • HEALTH • MEDICINE • WELLNESS • HEALTH • MEDICINE • WELLNESS • HEALTH • MEDICINE • WELLNESS • HEALTH • MEDICINE • WELLNESS • HEALTH • MEDICINE • WELLNESS • HEALTH • MEDICINE • WELLNESS
JULY 27, 2018
AIKEN-AUGUSTAʼS MOST SALUBRIOUS NEWSPAPER • FOUNDED IN 2006
AUGUSTARX.COM
BODY PARTS: THE OCCASIONAL SERIES
BIG What is? What is it that’s so big? It’s the body’s largest organ (or organ system). Do you know what it is? Conduct a man on the street poll on this question and you might be standing there for awhile before anyone came up with the correct answer. If you got impatient and told people the answer and then asked them to define or describe it, you might be standing there for additional hours. Let’s try it right here and now. The answer you’ve been thinking about... was it the integumentary system? Correct! You get the gold star! If that wasn’t what you had in mind, at least now you know the right answer. All you have to do now is define it. It’s not easy, is it? The integumentary system either has the worst publicity team working for it, of most of us slept through class on the days it was discussed. Most of us have no idea what it is, assuming we’ve even heard of it. Despite its comparative anonymity, it’s a complex and sophisticated system, but then, what component of
human beings (and every other living thing) isn’t?. Let’s start with the basics. The word itself come from the Latin integumentum, which means “a covering.” That was a perfect description once upon a time when the integumentary system’s single biggest component, our skin, was viewed as just that: a covering. These days we realize skin is far more than just the casing we’re enclosed in. Skin prevents dehydration. It cushions, waterproofs and protects what lies beneath. It promotes the body’s thermal equilibrium, protecting our core temperature yet also keeping us cool through its temperaturesensing perspiration system. It maintains the body’s homeostasis, its ability to function regardless of outside conditions, whether hot and humid, sub-zero, underwater, you name it. It is the body’s first line of defense against infection and disease, and repairs itself when injured. It even manufactures nutrients (vitamin D) when exposed to sunlight and at the same time protects us from sunburn by secreting melanin. Skin is so important that deprived
of it, a person would quickly die from infection and heat loss, and pardon the expression, but we haven’t even scratched the surface of everything skin does for us. Skin covers every square centimeter of the body, in some places mere hundredths of an inch thick, elsewhere (like the heels and soles of our feet) close to a quarter of an inch thick. It is our largest organ (yes, it’s on a par with the liver, brain and other name brand organs), comprising 10 to 15 percent of our total weight (as much as 22 lbs for a 150 lb person). And every single one of those square centimeters has sensitive receptors for touch, heat, cold, pressure, liquid and pain. They don’t multi-task: there are specific and specialized receptors for each sensation. Pain receptors, for instance, are different from touch receptors. At this point a logical question would be “Why not just call it skin instead of the integumentary system?”
That would be because skin is just, to mix our metaphors, the tip of the integumentary iceberg. The system is made up of everything connected to the skin, a lengthy list that includes everything used by skin to do its job. That means our toe- and fingernails, sweat glands, oil (or sebaceous) glands, and every one of the roughly 5 million hairs that cover our body. The 100,000 hairs on the average scalp may come to mind first, but there are 4.9 million more spread around virtually the entire body (except the palms of our hands and the sides of fingers and toes, the soles of our feet, lips, and certain parts of our external genitalia). All of them are connected to capillaries and nerves at their base (or follicle), providing nutrients and sensory information. When we feel a cool breeze on our skin, it’s likely fine hairs that convey that sensation. Some hair has a more clearly protective
Even eyelashes play a key role in the integumentary system.
Please see BIG page 2