Skin, is it for beauty only?

Skin functions to keep body fluids in and keep extraneous substances out of the body.

The epidermis, though it acts acts as a fluid barrier, it is not totally impervious. Indeed, if working with noxious chemicals, to avoid harm to it and systemically, wear additional protection. This permeability also allows for administration of medication by slow absorption through it.

The integument is described as having three layers. The epidermis, the outer layer, has the keratinocyte and the melanocyte. The process is the new keratinocyte forms under the older and the cells as they are moving out lose the nucleus and keratinize. The loss of keratin from the surface is a continuous process. In psoriasis & ichthyosis the keratinization is genetically flawed.

The melanocyte produces the pigment melanin which bears influence on the color of your skin, hair, and iris. Melanin is not the only determinant of skin color, though, in blacks it is predominantly so. In the literature it states that the blacks and the whites have the same number of melanocytes and the production of the respective melanocyes vary. In whites and other races other pigments and other factors bear influence on skin color. And, the albino, the vitiligo patch, the freckle, all attest to nature liking to play fickle with the melanocyte.

The blood vessels to the skin may be dilated or constricted, hemoglobin may be well oxygenated or not, hemoglobin level may be low or normal, and high levels of carotene or bilirubin all are factors affecting skin color.

Vitamin D, the sunshine vitamin, is produced by the skin. In northern climates there is too little sun exposure, too little ultra violet ray exposure, for the skin to supply minimal vitamin D needs. So commercially marketed milks are vitamin D fortified.

The melanin production can be stimulated with sunlight and ultra-violet light. It should be added that extensive exposure to either has an additive risk of skin cancer with time, and, such exposure deteriorates elastin in skin and increases wrinkling.

The melanocyte is also influenced by the melanocyte stimulating hormone produced in the pineal gland, perhaps under influence of the thalamus, and, the circadian cycle. ( Could it be that shining light on the skin away from the eyes during sleep could mitigate seasonal affective disorder?)

The pigmented nevus can occur post birth. Up to the age of juvinile the compound juvinile nevus can develop as a benign change. Adults can have palpable raised nevi that are benign. If in the adult a mole changes to lighter or darker, changes in size or the margin becomes irregular, then great haste for medical consultation is urged. The need for early diagnosis of a melanocarcinomatous change cannot be over emphasized.

The dermis, also called corium, has the histiocyte, the mastocyte, and the fibrocyte as the main cells. And the keratized appendages hair and nails are seated here, as are the apocrine and the eccrine sweat glands. The sebaceous gland opens into the hair cell follicle. These glands and hair follicles penitrate the dermis and are subcutaneous in the lowest parts. In the split skin graft a surgeon takes the top layer of skin and leaves the base of the glands and hair follicles at the donor site, and at the donor site the skin appendages regenerate along with the epidermis. (The self donor is assured of tissue compatibility.)

In the dermis the fibrocyte grows in a pattern of undulating density and length of fiber which under microscope look finger-like and are called rete pegs. Not only does the dermis support the sweat glands and hair follicles it carries blood and lymph vessels and nerve fibers and nerve endings. Of note is the Pacinian corpuscle, a pressure and vibration sensor, could you judge the quality of a hug without it? The corium is also the location for pain and itch sensors, and touch discrimination.

The histiocyte and the mastocyte are two other cells in the dermis. They are both deemed defenders of health. The histiocyte, also called a phagocyte, engulfs foreign matter and breaks down harmful substances, or encloses it for discharge. The mastcell is involved in the immune response. In the ordinary sense the immune response is the body creating a protein that fixes to another protein and the combined proteins reduce the ill effect of a harmful protein or chemical. Immunity to measles, for example, after a prior exposure to it is a case of a good outcome from an immune response. An allergy is an example of natures defense system having gone bad.

The mastocyte has granules that contain heparin and histamine. The mast cell comes in several variations, and is present in the dermis and other tissues, and in the blood the basophil is an equivalent. A scratch to the skin causes a lighter colored raised line behind the scratch and a redflare to each side along the scratch, this triple response, so called, is interpreted as caused by histamine release by the mast cell. A continued scratch, if done long enough, will produce eczema in the scratched area. If such eczema is localized it may be called atopic allergy, or a neurodermatitis.

What does atopic mean medically? If we compare the word to atonic, which means no tone, when used to describe muscle tone, then we expect atopic to mean, no location, or off topic, or misplaced. By contextual inference I conclude that mostly atopic and allergic are used as near synonyms in medical writings.. This is not really strange as the portal of entry of the antigen and the the organ with the reaction are commonly disparate. Exceptions do occur, as when skin reacts to the exposure of poison ivy. Here the allergic reaction occurs at the site of the allergen entry. It is on topic. It is more typical that a medication taken by mouth might cause an exanthema or urticaria, and other reactions. This latter response is interpreted as being atopic. Allergic reactions are more commonly atopic than topic. An allergist might do skin tests to test for allergens causing asthma or hay fever, though correlation isn't perfect, it's good enough to be worthwhile.

Let us take note that the mast cell and the basophil are not only distributed in many tissues and the blood they are also capable of massive over-reaction. Some times a severe over-reaction can follow after minor warning of a past allergic reaction. Peanuts and other nuts or food allergies and a medication such as penicillin and other medications have been known to cause a massive allergic response, anaphylaxis, in which death can occur within minutes, if intervention with epinephrine (adrenaline) is not available.

The skin has the apocrine and the eccrine sweat glands and the base of each arises from the subcutaneous layer. The apocrine secretion is thicker than the eccrine sweat and in humans is odorless, but, with skin bacteria breakdown of apocrine secretions odor occurs. In some animals the apocrine secretion has a sexual allure, hence, musk from the musk deer is used in perfume.

In humans most of the apocrine glands are in the axillae, the armpits, these and the eccrine glands on the soles and palms react reflexly to emotion. The forenamed glands have no physiological regulatory function but they provide a clue to an emotional tension. The dryness or wetness of hands or feet are constitutionally variable. Now, I am not familiar with Chinese medicine but am inclined to speculate whether they might infer differing metabolic needs based on whether one's hands are - wet and warm, wet and cold, dry and warm, dry and cold?

Eccrine glands are present in all areas of the skin and those on the scalp, face and the body respond reflexly by sympathetic nerve connections as temperature regulators. The secretion is watery and hypotonic to the interstitial fluid. Since evaporation from the skin does the cooling, it follows that cooling is slower when high humidity slows evaporation. The sweat contains both chloride and sodium and there is some sodium reabsorption, so in prolonged activity in heat and high humidity salt intake should be added to the water intake. In the usual situation plenty of water is all that is needed.

Although metabolic hypochloremic alkalosis can occur in prolonged heavy exercise in high temperatures is an unlikely event, it, along with heat cramps, heat exhaustion, and heat stroke, are mentioned because of their seriousness. Treatment is not here dicussed. Only this tangential thought - are some of the dugout drownings due to heat cramps?

The sebaceous gland is the final appendage of skin to be discussed and this will be covered under the term, acne.

The skin keeps body fluids in, is a barrier to exterior substances entering, and it helps control body temperature, it adds to a few metabolic services, and, with few exceptions adds beauty. It is worth preserving. The skin, like a mirror, may sometimes reflect good or bad health, and may reflect blemish or beauty. The pursuit of health and beauty is broad enough that a link(s) to additional information and products is apropo.