In zootomy and dermatology, skin is an organ of the integumentary system composed of a layer of tissues that protect underlying muscles and organs. As the interface with the surroundings, it plays the most important role in protecting against pathogens. Its other main functions are insulation and temperature regulation, sensation and vitamin D and B synthesis.

Mammalian skin often contains hairs, which in sufficient density is called fur. The hair mainly serves to augment the insulation the skin provides, but can also serve as a secondary sexual characteristic or as camouflage. On some animals the skin is very hard and thick, and can be processed to create leather. Reptiles and fish have hard protective scales on their skin for protection, and birds have hard feathers, all made of tough β-keratins. Amphibian skin is not a strong barrier to passage of chemicals. A frog sitting in an anesthetic solution will quickly go to sleep.

Skin is composed of the epidermis and the dermis. Below these layers lies the hypodermis(subcutaneous adipose layer), which is not usually classified as a layer of skin.

The outermost epidermis is consists of stratified squamous epithelium with an underlying basement membrane. It contains no blood vessels, and is nourished by diffusion from the dermis. The main type of cells which make up the epidermis are keratinocytes, with melanocytes and Langerhans cells also present. The epidermis can be further subdivided into the following strata (beginning with the outermost layer): corneum, lucidum, granulosum, spinosum, basale. Cells are formed through mitosis at the innermost layers. They move up the strata changing shape and composition as they differentiate, inducing expression of new types of keratin genes. They eventually reach the corneum and become sloughed off (desquamation). This process is called keratinization and takes place within about 30 days. This layer of skin is responsible for keeping water in the body and keeping other harmful chemicals and pathogens out.

Blood capillaries are found beneath the epidermis, and are linked to an arteriole and a venule. Arterial shunt vessels may bypass the network in ears, the nose and fingertips.

The dermis lies below the epidermis and contains a number of structures including blood vessels, nerves, hair follicles, smooth muscle, glands and lymphatic tissue. It consists of loose connective tissue otherwise called areolar connective tissue - collagen, elastin and reticular fibres are present. Erector muscles, attached between the hair papilla and epidermis, can contract, resulting in the hair fibre pulled upright and consequentially goose bumps.

The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle as well as supplying it with blood vessels and nerves. It consists of loose connective tissue and elastin. The main cell types are fibroblasts, macrophages and adipocytes (the hypodermis contains 50% of body fat). Fat serves as padding and insulation for the body.

The skin must be regularly cleaned. Unless enough care is taken it will become cracked or inflamed. Unclean skin favors the development of pathogenic organisms.

The skin supports its own ecosystems of microorganisms, including yeasts and bacteria, which cannot be removed by any amount of cleaning. In general these organisms keep one another in check and are part of a healthy skin. When the balance is disturbed, e.g., by antibiotics which kill bacteria, there may be an overgrowth and infection by yeasts. The skin is continuous with the inner epithelial lining of the body at the orifices, each of which supports its own complement of flora.

Your skin is your armor, your shield from the elements. Yet when was the last time you really thought about what you need to do to take care of it? Throughout your life, genetic and environmental factors will cause a lot of wear and tear to your skin. But you are never too young or too old to start taking care of your skin.

If you take care of your skin, your skin will take care of you! But with all of the lotions, creams, and potions on the market, it can be difficult to know which product will work for you. Many products claim to remove wrinkles or heal dry skin. Others claim to contain expensive ingredients that they say will improve the effects of the product.

Exercise, rest, and good nutrition lay the foundation for beautiful, healthy skin, inside and out. A proper diet is not only good for your overall health, it also helps to ensure that your skin will receive all of the vitamins, minerals, and nutrients that it needs to maintain and repair cells. Drinking purified water is another good way to keep your skin healthy. Water helps to hydrate the skin and move waste and nutrients through the system. It is very effective mixing a teaspoon or capful of Organic Apple Cider Vinegar in with your water. Do not drink Tap Water.

The most important way to care for your skin is to protect it from the damaging rays of the sun. Ultraviolet radiation damages the skin and can lead to wrinkles, premature aging, age spots, and cancer. Take extra precautions to make sure your skin is not exposed to the sun's rays. Use a natural sunscreen, or a moisturizer that contains sunscreen (at least SPF 15) everyday. Your skin does need some sunlight 10-15 minutes of direct exposure daily.

When you do use soap, try using a natural very mild soap that does not contain any dyes, parabens or perfumes. Follow up the bath with a moisturizing lotion, concentrating on problem dry areas. A good all natural moisturizer is one of the foundations for a healthy skin care regimen. Continue moisturizing throughout the day to keep skin healthy. Your hands and face are particularly susceptible to daily damage, and may need to be moisturized several times.

Unless your skin is very oily, you will want to use a moisturizer everyday to keep your skin hydrated and healthy. Your skin needs moisturizer all year long as both the indoor winter heat, and summer sun can be equally damaging to your skin.

Apart from the services offered at skin clinics, many creams, gels and ointments that claim to treat acne, diminish sun or age spots and enhance skin elasticity are widely available in the market. There are scrubs, cleansers, masks, over-the-counter skin medicine and skin peel formulations, all offered at various price ranges. Most can be bought at department stores or drugstores, but the fact is that very few of these so- called miracle products actually work.

As we age, our body undergoes various changes, and so does our skin. In our skin, we have tissues known as collagen and elastin. These tissues are mainly responsible for making our skin firm and stretchable. As we grow older, the amount of collagen and elastin in our skin naturally diminishes. As a result, our skin becomes less elastic and weaker, thus creating "wrinkles".

Over the years, beauty experts and skin doctors have come up with a vast array products to treat and minimize wrinkles. Anti-wrinkle creams and ointments help reduce the appearance of wrinkles and prevent new ones from forming. These wrinkle ointments and anti-aging creams help a lot in restoring the skin's firmness and elasticity. In addition, these products contain anti-oxidants and retinol that not only aids in reducing wrinkles and fine lines on the skin, but also stimulates collagen production.

For people seeking solutions to severe damage that has already been done to the skin, there are a number of treatments available ranging from chemical peels and dermabrasion to the latest and technologically advanced, computerized laser resurfacing. However, many people looking for skin repair are hesitant to try chemical or laser peels due to the painful procedure and long recuperation period they have to undergo. The results of these procedures however, are fantastic.

One less painful procedure is the particle skin resurfacing procedure. The process is removes the outer layer of skin in a highly controlled manner. Because of its preciseness, it is practically painless. By repeating this procedure a number of times, the younger skin moves to the surface, thus promoting visible changes in the skin's texture, color and appearance. The benefits of this skin resurfacing procedure are that it causes very little pain or discomfort, no recuperative period is needed, there is minimal risk, it can be used for all skin types, and no anesthesia is required.

Terms on this page

Acne

• An inflammatory disease of the sebaceous glands and hair follicles of the skin that is marked by the eruption of pimples or pustules, especially on the face.

Bacteria

• Microscopic unicellular prokaryotic organisms characterized by the lack of a membrane-bound nucleus and membrane-bound organelles.

Dermis

• The sensitive connective tissue layer of the skin located below the epidermis, containing nerve endings, sweat and sebaceous glands, and blood and lymph vessels.

Epidermis

• The outer, protective, nonvascular layer of the skin of vertebrates, covering the dermis.

Hypodermis

• A subcutaneous layer of loose connective tissue containing a varying number of fat cells.

Pimples

• A small swelling of the skin, usually caused by acne; a papule or pustule.

Ultraviolet radiation

• Invisible electromagnetic radiation between visible violet light and X rays.

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