What are the different layers of skin

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The skin (Cutis) is a vital organ that covers the entire outer surface of our body. It is stretchable and elastic, separates the organism from the outside world and protects it from drying out and from damaging influences such as pathogens and sunlight. Read everything important about the layers of the skin, their functions and important diseases of the cutis!

What is the skin

The skin (cutis) is a surface organ, the largest single organ in the body. As a protective covering for our body, it covers an area of ​​one and a half to two square meters in an adult of medium size. With a thickness of one to two millimeters, the skin organ weighs around three and a half to ten kilograms. Their color changes from person to person - it depends on the amount of blood, the pigment content and the thickness of the epidermis (top layer of the cutis).

How many layers of skin does a person have?

The structure of the skin comprises three layers. From the outside in, these are:

  • Epidermis
  • Dermis or corium
  • Subcutis

Epidermis

The epidermis consists for the most part of a horny layer that flakes off to the outside and constantly renews itself from below. Read more in the article Epidermis.

Dermis (corium)

The dermis is the middle of the three skin layers. It consists of tight connective tissue and contains, among other things, sebum glands. Read more about the dermis in the article Dermis.

Subcutis

The subcutis consists of loose connective tissue with more or less stored fatty tissue. You can find out more about this in the article Subcutis.

Appendages

The skin appendages include hair, nails and glands such as sweat and sebum glands. You can read more about the latter in the article sebum glands.

What is the function of the skin?

The function of the skin is primarily to provide protection for the body. How vital the cutis is can be seen when larger areas have been destroyed, for example by a burn. Loss of 20 percent of the skin can be fatal. In addition to its protective function, the cutis also fulfills other tasks, such as as a sensory organ.

Skin care in winter

  • Moist and fat

    The skin is a high-performance organ: around two billion skin cells protect the organism from pathogens, UV radiation, overheating and dehydration. They have to do a lot, especially in winter. Due to the temperature changes, the skin loses moisture and below 8 ° C the organ stops producing sebum. This is because the blood vessels contract at cold temperatures, and fewer nutrients and oxygen reach the surface of the skin.
  • Well-groomed face

    For you this means: Provide the skin with sufficient moisture and oil in winter so that it does not become cracked or brittle. In winter, all skin types can therefore tolerate more oily care. Clean your face with pH-neutral soap or a mild cleansing milk. Then apply a high-fat, moisturizing face cream every day. The following applies: the colder it is outside, the less water the care product should contain.
  • Supple lips

    The lips in particular quickly become rough and cracked in winter. They do not have sebum glands that protect against moisture loss. First rule: do not wet your lips with your tongue. That dries them out quickly. It is better to have a high-fat care stick with beeswax or palm oil and jojoba oil ready. These substances protect your lips. Think of a care stick with a UV filter when you go for a walk or do winter sports.
  • Delicate hands

    Even if the hands have a few sebum glands - in winter, when they are often in contact with the dry, cold air, the sebum production is insufficient. The result: the hands become easily brittle and cracked. The antidote: a moisturizing hand cream brings the balance of the outer skin layer back into balance. Red, brittle winter hands care for a pack or a massage with almond oil (depending on the strain, once or twice a week).
  • Healthy feet

    Cold and thick stockings cause problems for the feet, the callus cracks faster. Treat yourself to a foot bath with herbal salts once a week. Then smooth the cornea with milk fat or a special foot cream with urea (urea).
  • Whole body wellness

    The same applies to the rest of the body: the skin receives less oxygen and no sunlight under thick winter clothing than in summer. Due to the constant contact with the fabric, it can easily roughen and flake. Shower oils, fatty lotions or body oils are suitable for daily care. Or take a nice oil bath or, as it is said, Cleopatra with a large glass of milk and a tablespoon of oil. Then use a greasy and moisturizing lotion.
  • Which is still good

    In cold times you can do even more for your skin: Eat a balanced diet, for example. Fresh fruits and vegetables provide the cells with important vitamins and minerals. And: Drink enough, preferably water, fruit spritzers, fruit or herbal teas. In this way, the cells also receive moisture from the inside. A lot of exercise in the fresh air strengthens the blood circulation in the skin.
  • Where you can still support your skin

    Alcohol and nicotine put a strain on the sensitive outer shell. This also applies to alcohol if it is not drunk but is contained in skin care or cleaning products. Peelings are also not a good idea in winter. Stress and lack of sleep also weaken the skin's natural balance. And: radiators in the rooms should be equipped with humidifiers. Alternatively, you can also set up bowls of water in the rooms against the dry heating air.
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    Medical editor and biologist

Protective function of the skin to the outside

The outer horny layer (part of the epidermis), which is saturated with fatty substances, protects the organism on the one hand from excessive water loss through evaporation. On the other hand, an intact skin prevents the penetration of pathogens and harmful substances such as chemicals. To a certain extent, it also offers mechanical protection for internal structures and organs from blows or bumps, for example.

The sweat from the sweat glands and the sebum from the sebum glands together form the so-called protective acid mantle of the skin. Its low (acidic) pH value has an antimicrobial effect: it inhibits the growth of many bacteria and fungi on the cutis.

Natural sun protection

An important task of the skin is also the reflection and absorption of sunlight through the horny layer and the skin surface film. Rays penetrating deeper are from the Melanin pigment - a black-brown to reddish dye - almost 100 percent absorbed and converted into heat.

So if someone spends a lot of time in the sun and gets tanned, it simply means that the skin has made more melanin to better protect itself from the UV rays. Incidentally, the increased melanin formation is stimulated by the UV-B component in sunlight.

Depending on the skin type, everyone naturally has more or less melanin stored in their skin. Dark-skinned people have a particularly large amount of the color pigment. Their skin is therefore less sensitive to light than that of fair-skinned people.

Another strategy to protect the skin against sunlight is the so-called Callosity: Repeated exposure to UV-B light causes the top layer of skin - the cornea - to thicken. A light callus forms within two to three weeks, which persists for weeks and improves the skin's own protection: the skin thickening reflects, filters and scatters sunlight.

The UV rays from the sun and solariums can damage the genetic material of the cells. Although the body has repair mechanisms at its disposal, it cannot always and certainly not completely eliminate the damage. Possible consequences: premature aging of the skin and skin cancer.

Protective function inside

The inward protective function of the cutis consists in the formation of antibodies. When the body's own defense system is mobilized by the Langerhans cells in the epidermis, the body pumps blood and lymph into the affected skin region. The consequences are redness, swelling and the formation of wheals. Rashes in infectious diseases such as rubella, measles, scarlet fever and reactions to vaccinations are the result of this immunological defense reaction.

Thermoregulation

A contraction (contraction) of the cutaneous vessels prevents excessive heat emission. Goosebumps serve the same purpose: They are caused by contraction of the hair follicle muscles on hairy parts of the body. As a result, the cutis forms small bumps and the fine hairs stand up. This reduces the heat dissipation.

By widening the vessels, on the other hand, heat dissipation is promoted and thus heat build-up in the body is prevented.

The release and evaporation of sweat is used for heat regulation.

Sensory perception

The sensory organ, the skin, registers stimuli such as pressure, temperature and pain through specific receptors. One speaks here of surface sensitivity. You can read more about this in the article Tactile Perception.

Other tasks of the skin

The Cutis also fulfills other functions. For example, to a small extent substances that are otherwise only excreted via the kidneys (urinary substances) are secreted via sweat glands (such as table salt). In addition, the formation of vitamin D takes place in the epidermis under the action of sunlight (more precisely: UV-B light). Its main function is to regulate the calcium and phosphate balance. Both minerals are important for building bones and teeth, among other things.

Where is the skin located?

The cutis covers the entire surface of the body. At the body orifices (mouth, nose, genital region) it passes into the mucous membrane.

Regardless of the three-layer skin structure, two different appearances of the cutis on the body can be distinguished:

The skin on the soles of the feet, the palms of the hands and the insides of the fingers runs in fine furrows that are arranged in parallel - like fine ridges. This structure is used to make the cutis rough and grippy, to give them hold. Doctors speak of the so-called inguinal skin. It makes up about four percent of the body's surface.

The skin on the rest of the body (around 96 percent of the body surface) consists of rhombic to polygonal furrows that are genetically fixed in their shape and run in characteristic lines. Hair grows out of the furrows of this field skin, and sweat glands open out via an outlet duct at the raised areas.

What problems can the skin cause?

The cutis can cause numerous problems such as abscesses (encapsulated collections of pus), boils (purulent inflammation of hair follicles) or herpes infections (such as cold sores, shingles).

Atopic eczema (neurodermatitis) is a genetic, chronic skin disease that is associated with inflammatory changes in the cutis and severe itching. It runs in bursts and can be "triggered" by so-called provocation factors. These include, for example, frequent washing, profuse sweating, pollen, animal hair, infections and stress.

Psoriasis is a chronic inflammatory skin disease that leads to scaly, itchy changes in the cutis. The knees, elbows and scalp are particularly affected. In some patients, the joints or nails can also be affected.

With contact dermatitis (also called allergic contact eczema), the skin is over-sensitive to contact with certain substances such as fragrances or nickel. Typical symptoms are redness and severe itching.

If the immune system is weak, it can lead to a fungal disease of the skin (dermatomycosis).

Warts (verrucae) are small, sharply defined growths on the epidermis. They are generally benign. The human papillomavirus (HPV) triggers the development of warts. There are different types of warts such as "common" warts (especially on the hands and feet) or plantar warts (almost only on the soles of the feet).

A birthmark (pigment nevus) is the result of an increase in pigment-forming cells (melanocytes) in the epidermis. It is also known colloquially as a mole. The predisposition to birthmarks is genetic. However, their expression is significantly influenced by sunlight. Birthmarks are mainly formed on parts of the body that are exposed to the sun.

If the sunlight is too strong, sunburn can develop - the cutis burned by the UV light. Some medications can increase the risk of sunburn because they make the cutis more sensitive to light. These include, for example, St. John's wort and certain antibiotics.

Frequent sunburns (especially in childhood) promote the development of skin cancer. The term refers to various malignant tumors of the cutis. The most important are basal cell carcinoma (basalioma), squamous cell carcinoma (squamous cell carcinoma, spinalioma) and malignant melanoma.

A common disease of the skin in adolescents is acne (acne vulgaris) - a hormone-dependent disease of the sebum glands that occurs primarily during puberty.

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