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The Hunger Project Bolen Report
Ohm Society
Skin Print E-mail
by Ron Kennedy, M.D., Santa Rosa, CA

Dr. Kennedy As you may have noticed, skin covers the entire exterior surface of the human body. Its functions are to (1) protect the deeper tissues from injury, (2) prevent the wholesale escape of fluids from the body, (3) help maintain body temperature within a constant range, (4) assist the kidneys in excreting salt and waste products, (5) sense the presence of dangerous, possibly injurious, conditions in the external world and (6) serve as an organ of sensual pleasure. Consult your encyclopedia under "skin" for a diagram of human skin.

The top layer of skin is called the "epidermis." It includes three layers. The topmost layer, which you can easily see with your eye, is the stratum corneum, or hardened layer of skin. This layer is composed of "cornified squamous epithelium," which is dead and soon to be sloughed off. Each time you rub against something or take a bath, you lose millions of these dead cells. This layer of skin contains no nerve cells. Sensations of hot and cold, sharp and dull are not perceived by this layer of skin, but rather through it. If this were not the case — if this layer did contain nerve cells — life would be a very painful situation indeed.

Below this layer lies the very thin, one cell layer thick, "stratum lucidum," or clear layer. This clear layer is nothing more than a layer of freshly made cornified squamous epithelial cells. If you burn yourself or sustain an injury to the stratum corneum and stratum lucidum, but not deeper than that, we say you have a "first degree" burn or injury.

Bacteria are found in the skin down to this level. These bacteria represent a variety of species, most of which are harmless and known as "normal flora." However, contained in these normal bacteria, there may be some which will cause disease if they gain access to deeper layers of skin as happens with burns, cuts, scrapes, etc. in which the skin is penetrated to deeper layers.

Streptococcus is the most common bacteria which causes skin infections. A strep skin infection is diffuse and without pus formation. Staphylococcus, skin infections, on the other hand, progress to pus-filled, discreet, walled-off carbuncles.

Below the stratum lucidum, but still part of the epidermis, is the "stratum germinativum," or germinative layer. This layer of skin is composed of living cells, which are destined to grow closer to the surface, die and transform into stratified squamous epithelium.

Skin originates at the bottom of the germinative layer and grows outward. Your skin is totally replaced over a period of approximately one month. Penetrating through the stratum germinativum are the sebaceous glands which originate in the dermis and secrete an oily substance serving to lubricate the skin. If you suffer a burn or injury as deep as this level, but no deeper we say you have a "second degree" burn or injury. You can have such an injury and still suffer no permanent scarring.

Below the stratum germinativum is the "dermis," which is made of connective tissue (proteins called "collagen" and "elastin") penetrated by nerves, veins, arteries, venules, arterioles, capillaries, lymph ducts and containing sweat glands and hair follicles.

As you age, the collagen strands form crosslinked bonds with each other, decreasing the elasticity of the skin, resulting in the wrinkles we associate with aging. The presence of free radicals speeds up this process, and the presence of antioxidants slows it down.

There are two kinds of sweat glands: "apocrine" and "eccrine." Apocrine sweat glands are concentrated under the arms, are larger than the eccrine glands, secrete a milky fluid and are responsible for body odor. Some fair-skinned individuals have few or no apocrine glands and have no need for deodorants. Darker skin is associated with large numbers of apocrine glands. Eccrine sweat glands are located throughout the body and secrete a thin, odorless liquid made mostly of salt water.

In order for a cut to bleed or a burn to hurt, the injury must penetrate at least as deep as the dermis. Above this level, there are no blood vessels or nerves. If you suffer a burn or injury as deep as this level, but no deeper, we say you have a "third degree" burn or injury. If you have an injury this deep or deeper, you will have some degree of scarring.

Cellular life must exist in a fluid environment in order for cellular reproduction to occur. The dead skin on the surface serves as a container for these deeper processes, and can be thought of as a protective device, just as a test tube is a protective devise allowing chemical reactions to happen in an environment undisturbed by the outer world. It is important that the fluids in this living test tube not escape — therefore, the stratum lucidum is impermeable (impenetrable) to body fluids. Very few substances are able to penetrate in the opposite direction, so that the internal environment is not only held in but also is protected from the external environment.

Skin has the most important role of any organ in regulating body temperature. It does this by contracting and relaxing the capillary bed. There are approximately fifteen miles of capillaries for each square inch of skin, so any contraction of this capillary bed serves to hold a large volume of blood deep within the body, which otherwise would come close to the surface and lose its heat. This serves to retain heat within the body. Conversely, when the weather is hot, or with vigorous and/or sustained exercise, the capillary bed dilates bringing larger volumes of blood near to the surface, thus losing heat.

The sweat glands assist in this process by placing water on the surface of the skin. The evaporation of water is an endothermic phenomenon; i.e., it requires heat for water to evaporate. Part of this heat is derived from the body (from the dilated capillary bed) and part from the environment. The part which is derived from the body is lost to the body, thus leaving the body cooler.

Central control of body temperature is located in the hypothalamus of the brain, which is connected by nerve cells to all the capillary beds and sweat glands throughout the body. Skin is useful for losing heat up to an ambient temperature of 115 degrees Fahrenheit. Above that it does not work, as the skin absorbs as much or more heat than it can dissipate by sweating and vascular perfusion.

Contained in sweat is salt in higher concentration than found in the body fluids and also waste products that also are excreted through the kidneys. Each sweat gland can be considered a tiny kidney-helper, and because there are hundreds for every square inch of skin, this represents a significant contribution to cleansing the body of excess salt and waste products.

An interesting sidelight is that fingernails and toenails are made of skin products. Nails are made hard by the same keratin contained in the stratum corneum, except even more concentrated. Hair also is derived from skin. The follicles from which hair grows out are made of modified skin cells. Even the covering of the cornea, the clear part of the eye, is made of layers of cells continuous with, and modified from, skin cells.

In embryonic development, skin is derived from the outermost of the three basic layers of cells, the ectoderm. The brain, spinal cord and all the nervous tissue of the body also are derived from the ectoderm. The ectoderm simply invaginates (turns inward into a tubular formation), which then meets in the middle of the back and seals itself off from the outside.

There are two other layers of cells in the embryo, the mesoderm and the endoderm. The mesoderm forms all the connective tissue of the body along with the heart and blood vessels — as well as the lymph system, spleen and bones. The endoderm forms the liver, pancreas and digestive tract from the lips to the anal sphincter.

The neural sensors of the skin include specialized organs to sense hot/cold, others to sense pressure, others to sense light touch. Pain is the individual's interpretation of the sensation caused by the release of large numbers of neurotransmitters into the synapses between nerve cells in the skin. This happens in response to severe hot, cold, pressure or tissue injury, such as that caused by cutting or scraping. Pleasure is the individual's interpretation of the sensation caused by the release of smaller numbers of neurotransmitters into the synapses between nerve cells in the skin. Pleasure and pain are caused by the same process with pleasure transforming into pain at some point on a continuum of increasing intensity, according to the nature of the individual experiencer.

Sensual love probably would not be possible without the sensations derived by light touch of the skin. When administered by touch of a loved and loving person, these sensations add immeasurably to the pleasure of living.

Skin color is determined by the concentration of melanocytes in the skin. These cells contain melanosomes which produce the pigment melanin. Melanin serves the function of protection from ultraviolet rays of the sun. Usually, melanin is gathered together in clumps within the cell. Tanning represents the production and dispersion of melanin throughout the melanocytes, and happens as a result of measured exposure to sunlight.

Over about eighty generations of people (2000 years), skin color will transform from light to dark by increasing the number of melanocytes, under the influence of levels of sun exposure common to the equatorial regions of the earth.

Exposure to massive doses of sunlight over a short period of time, allows UV rays to damage the capillary vessels in the dermis, causing them to swell, releasing fluid into the skin, resulting in the inflammation of the skin tissues. This is, of course, known as "sunburn." Ordinary, everyday exposure to sunlight, even indirect sunlight, has been shown to be the major cause of aging of the skin. It is also known to be strongly associated with the later development of skin cancer.

To prevent sunburn, and the changes of skin aging, requires protection from sunlight. This can be achieved by daily application of sunscreen containing both UVA and UVB blockers, in high concentration. However, I question the wisdom of putting these chemicals on the skin every day, many of which are suspected carcinogens. A better solution is to limit your exposure to the sun and load up on vitamins A, C and E. These antioxidants will slow down skin aging, sunburn, and also benefit the rest of your body.

Aspirin is also effective against sunburn. On that special vacation, when you feel that you must spend the entire day at the beach, okay, slop on the sunscreen (and take A, C, E and aspirin), but let this be the exception.

The relationship between sun exposure and the development of skin cancer is irrefutable. If you have now, or have in the future, any blemish on your skin such as a mole which is new and changing, see a dermatologist immediately.

Vitamin D is manufactured in the skin as a function of exposure to sunlight. However, ordinary exposure is more than enough to get the job done. Consuming dairy products is not necessary for adequate levels of vitamin D.

Health and youthful longevity of the skin is aided by low levels of exposure to sunlight. A few years of intense tanning, although cosmetically pleasing in the short run, will damage the proteins collagen and elastin of the dermis and result in premature wrinkling.

Diet plays an important role in skin health. High levels of free radicals, in the absence of antioxidants to neutralize them (as is caused by digestion of fatty substances in middle or old age), causes crosslinking (as mentioned above) and thus acceleration of the wrinkling phenomenon of aging. A diet high in fat is partially dealt with by the sebaceous glands, which attempt to rid the body of excess fats. This can lead to clogged pores and small fatty cysts, which can become infected, forming carbuncles.

Below the skin, there is a pad of fat (the subcutaneous fat pad) which varies in thickness depending on the area of the body under examination, and varies according to the percentage of body weight which is fat. The thickness of this fat pad can be measured by taking a pinch of skin and measuring it with a caliper. This represents a double thickness of skin plus fat pad. Divide this number by two and subtract a couple of millimeters for the skin itself, and you have the thickness of the fat pad. This measurement is used in nutrition surveys to estimate level of nutrition, undernutrition and overnutrition. If you sustain a burn or injury into this layer, which also may involve muscle and bone, it is said that you have a "fourth degree" burn or injury.

The skin is a vital organ contributing greatly to overall health and vitality. Care of your skin is an opportunity to increase your health and longevity, but for this to be the case requires knowledge and attention.

One way to revitalize the skin is to stimulate it each day, before bathing, with a skin brush. The proper technique is to begin at the hands and feet and brush the skin vigorously toward the heart, covering each square inch carefully. This awakens the skin, enlivening the lymph drainage, capillary circulation and the sweat glands, which cleanse the entire body.

Retin-A is a medication derived from vitamin A which revitalizes the skin by repairing sun damage done over the years. Regular use on the face typically results in rejuvenation of the skin by five to ten years. If you want to use it, consult your physician for a prescription. This is one of the few patented medications worth using.

The information in this article is not meant to be medical advice.�Treatment for a medical condition should come at the recommendation of your personal physician.

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