It is also a sense organ and makes us feel pain like temperatures. A network of millions of nerve cells ensures that we can sense whether a surface is smooth or rough, hairy or made of plant fibers.
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With closed eyes we determine with our fingertips a sugar shaker, a chair ora book. What's more, the nerve cells even convey whether the sugar shaker is made of glass or ceramic, has a bulbous or cylindrical shape, whether it is a paperback book or a bound edition.
We feel that the book has a dust jacket and what the material consists of, whether the book contains about one hundred or two hundred pages, how tall the back of the chair is, whether it is made of wood or metal, if it is a desk chairor a living room chair.
With the senses, we not only grasp whether we touch something, but also what it is. Pain impulses direct the nerves of the outer skin directly into the brain and warn us in this way of dangers and possible injuries.
Other creatures, such as cats or walruses, can feel things with hair in the facial skin many times better than humans, and thus "see" the skin to a much greater extent.
The skin cells regulate the temperature of the body. A network of vessels and glands ensures that our body heat remains stable.
This super organ also acts directly on our communication and psyche - usually unconsciously. Shame and anger provide for a stronger circulation and drive us the blush in the face.
If we get scared, we get "goose bumps", we feel aggression, our neck hair bumps, our fingertips twitch with excitement.
The skin as a protective shield
It produces sebum like sweat and thus provides a coat that protects us from acidity and maintains a pH between 4.5 and 6.9.
The skin protection is not only directed to the outside, but also to the inside: With the sweat she transports the waste of the body to the outside. Conversely, the lipids in the sebum ensure that chemical substances and water are kept away from the body. At the same time, they ensure that the skin remains sufficiently moist.
This shield is vital: if we lose by burning, 20% or more of our skin tissue, then we can die from it.
The largest organ
A man of average height and weight is in a skin coat of about two square meters. It is one to two millimeters thick and weighs between three and ten kilograms.
Their color is different for each individual and comes from the amount of blood, the distribution of the pigments and the thickness of the epidermis.
Three Skin Layers
The skin is divided into the epidermis, the dermis and the subcutis. The epidermis is above all a horny layer. It serves the protection to the outside, constantly renews itself and drags to the outside. The dermis consists mainly of connective tissue and contains the important skin glands. Among other things, the sebum is produced here. The subcutis also contains mainly connective tissue, but this is much looser than in the middle layer and interspersed with fatty tissue.
It also includes the appendages. We count hair as well as nails, but also the sweat and sebaceous glands.
How does the skin protect?
The epidermis is filled with fats. As a result, the body loses less water, because the fats protect against evaporation. The three layers of skin also provide a buffer zone for bumps, bumps or stings that will not hurt the internal organs. The horny layer and the film on the epidermis are also a natural sunscreen. They reflect and absorb the sunlight. If the rays penetrate deeper, the melanin transforms them into heat. The acid protection in sweat and sebum prevents bacteria and fungi.
Thus, the sources of some diseases are already named: In too strong sunlight, horny layer, skin film and melanin can no longer absorb the rays;if the acid protection is damaged or fungi multiply like bacteria too much, then pathogens can invade.
The skin protects the body inside by making antibodies. The epidermis activates the immune system, and the body transports blood and lymph into the affected area - everyone knows this from their own skin when it reddens and warms around a wound.
The rash in infections such as measles, rubella or scarlet fever is not a symptom of the disease in the narrow sense, but on the contrary shows how the immune system fights off the disease.
warm-blooded animals depend on a constant body temperature. The skin plays a crucial role. The cutaneous vessels contract so that the body does not give off too much heat. That's why we have "goosebumps" when we freeze. The muscles on the hair follicles contract and the hair straightens.
Conversely, it also protects against overheating. If the heat builds up in the body, for example during physical exertion or great sun heat, then the vessels expand and more heat can leave the body.
Their function as heat filters can only fulfill them to a certain extent. To expand this framework, people wrap themselves in an "artificial skin", the clothes. This allows us to survive outside the( outdoor) temperatures that control our skin.
The extent to which we absorb or release heat through them differs from individual to individual, and has to do with genetic differences and skin color. People from cold climates generally have a higher cold tolerance than people from tropical regions because their skin absorbs more heat and gives off less heat. The heat absorption and delivery can also be trained.
A contact organ
The vernacular refers to with phrases such as "that gets under my skin" or "I get it skin swap" the skin as a seismometer for the psyche. In fact, it is not only a protection from the outside world, but also an organ to connect with the environment.
In the dermis lie the pain receptors, in the subcutaneous the receptors for pressure. Especially in the face, on the lips, the chin, the nose, the ear cups and the earlobes, the thermoreceptors collect. We have nearly ten times as many receptors for cold as for heat. It is no coincidence that these are mainly found in the described areas of the head: Lips, earlobes and the tip of the nose die as the first parts of the body from excessive cold - the receptors there warn the brain of this danger.
There are also receptors in the dermis that indicate the stretch of the skin.
The receptors for the sense of touch are found in hairless parts, especially in the external genitals, the anus, the nipples, the tongue, the fingertips and the lip. The highest concentration of nerve cells in men has the foreskin of the penis. Again, it is no coincidence that the tactile receptors are located in these places: With the fingertips we feel all kinds of objects, the anus we took early was whether harmful foreign bodies penetrate into the body, as well with the lips and tongue.
For example, if we feel the tiny barbs in the shell of a fruit on our lips, it protects us from eating that fruit, potentially damaging the inside of the body. In the sexual organs, the increased sensitivity through touch promotes sexual arousal.
The color of the skin
Not only does the skin color vary from individual to individual, it also shows itself clearly in different phenotypes of human groups. These differences promoted the pseudo-scientific theories of human races that pursued the primary goal of glorifying or degrading people of these supposed "races."Modern biology, however, shows that the color of the skin is primarily a result of adapting to sunlight and says virtually nothing to classify groups of people.
In 2003, George Chaplin and Nina G. Jablonski proposed that the black and white skin of humans was an adaptation to too much and too little sun. This would have been a balancing act. UV rays could be devastating to the naked skin cells, and reddish brown to black melanins are a natural sunscreen that prevents skin cancer. Particularly skin cancer endangered people with light skin in regions with strong sunlight such as Anglo Australians.
According to researchers, so dark skin was created to protect the folic acid in the body from UV radiation. In the sun-poor north, however, hardly any UV-B penetrated her anyway. But that brought no advantage, but a problem with it. Because UV-B rays are dangerous, but on the other hand vital, because they trigger the synthesis of vitamin D and thus have elemental importance for the calcium and phosphate metabolism, which in turn controls the bone structure.
So the skin color in the northern latitudes had to be bright enough to absorb enough UV-B rays for people to produce vitamin D.Without vitamin D, the body can not absorb calcium from the gut that makes up the bones and the skeleton can not develop normally. Without calcium, the immune system also breaks down.
Michael Hollick of the University of Boston, Massachusetts, and colleagues have underpinned these relationships through their medical studies over the past two decades. They also showed that sunlight at higher latitudes in winter is insufficient for vitamin D production because too little UVB radiation reaches the skin cells. That's why the people in the far north never really turned brown. Because your skin should always catch as much sun as possible. In mid-latitudes, however, people would turn dark in the summer, and in the winter, their skin would turn a pale color to store little sunlight at this time of the year. In the summer they are protected by their dark skin from too strong sun. In the tropics, however, the radiation is so strong that even with protected pigments enough vitamin D is produced.
Inuit in Alaska, Greenland and Northern Canada have a darker skin, but were only about 5000 years ago immigrated to the Arctic and on the other they had made themselves largely independent of the sun: Traditionally, the Inuit ate extremely high-fat marine fish and thus the foodwith the highest levels of vitamin DIn Africa, the Khoisan, the Bushmen of southern Africa, have a much lighter complexion than the Bantu people near the equator, which, according to Chaplin and Jablonski, is probably due to adaptation to the lower levels of UV radiation in South Africa.
Today, people often do not adapt quickly enough to the sun in a new home, according to Chaplin and Jablonski. This usually happens because of ignorance. For example, many Indians who came to Britain as citizens of the Commonwealth suffered from rickets and other vitamin D deficiency symptoms in northern England and Scotland.
Not only does it make vitamin D, it also removes sodium chloride from sweat. However, it fulfills this task in the mineral household, like so much in the evolution, only inadequate. Since sweat also serves to cool the body, we not only lose heat in the heat, but at the same time lose salt and have to recirculate it using mineral water, for example.
The surgeon at the entrance
It heals wounds so naturally that we hardly worry about how that happens. If a vessel in the middle layer of the skin is damaged, the nerves mediate the injury and platelets fill the affected area. But that's not all: The blood clots and at the same time forms a binder of protein. This fibrin is now an adhesive in the wound and hardened there. A protective layer is created and new skin cells form, finally the edges of the wound tighten, and the air dries the initially moist crust.
If the injury is in the lower or dermis, a scar remains. If only the epidermis is injured, everything heals again, the wound goes down to the deeper layers of the skin, a scar can remain behind. Protective cover and sense organ, robust and sensitive - our skin is just a real marvel.
Greasy or Dry
Human individuals have either oily or dry skin, or neither. The spectrum is big. Moisture not only varies from individual to individual but also changes with age and body region. Adolescents, for example, not only have pimples because their sebaceous glands run at full speed, but also often oily hair and oily skin. But if the sex hormones decrease with age, this process turns around: The skin of old people is dry.
Every skin type has its own problems. If it produces too much sebum, the fat thickens the surface, sebum and sweat clog the pores. This in turn allows fungi and bacteria to settle. However, too little sebum causes the important protective film of grease and moisture to be incomplete. The result is: Our skin becomes flaky and hypersensitive to cold or dry air. Many people who tend to freeze easily suffer from too-dry skin - often they do not know about this cause.
When does skin look nice?
skin is considered beautiful when its pores are small, with no dandruff, pimples or boils on it, if it reflects the light evenly, contains a little fat, shines and wrinkles little wrinkles. Too much fat is just as unaesthetic as dry skin. Evolutionary can explain our perception well: dandruff, pimples and boils may indicate basic diseases, a dry and dull skin on the one hand to age, secondly also on diseases - or both.
The old skin
age is not a disease;Our skin is already aging in young adulthood, which makes it thinner. We can not stop this process, but mitigate it.
Aging means that the papillae between epidermis and dermis change. Blood vessels in these papillae supply the epidermis with nutrients, oxygen and fluid. In young people, these papillae are close to each other and are long - the skin is plump and smooth. In older people, the papillae flatten and become less. The older we get, the less collagen and elastin the body makes and the skin loses its elasticity: we get wrinkles. Nutrients and oxygen now only slowly enter the upper skin layer: our skin is dull.(Dr. Utz Anhalt)
The skin - the largest human organ Human skin is the largest human organ - its surface covers up to two square meters. At the same time, there is often ignorance about how important it is for our lives. Many see it as a kind of shell that holds the inside of the body together.
This is what makes the skin, but it is much more than a "bag" for bones, flesh and internal organs. As a shell, it separates our body from the outside world, protects it from drying out, keeps pathogens out as well as sunlight, repels heat and cold.
The "skin filter" can be used medically: creams, oils, lotions healing baths and healing earth applied to the skin, provide the body with well-doing substances. Also active ingredients such as hormone patches or nicotine patches are absorbed through them.
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