The thickness of human skin varies. Human skin: functions, structure, interesting facts

The average skin area of an adult is 1.5-2 m². Thus, the skin is the largest organ of the human body. The skin consists of three layers: epidermis, dermis (the total thickness of which is 0.5-4 mm) and subcutaneous fatty tissue. The skin is the most important organ of our body, performing a number of vital functions: protective, receptor, immune, metabolic and thermoregulatory.

Skin structure

Only the thinnest layer of skin is visible to the eye - epidermis. Its thickness is only 0.1 mm. The epidermis consists of five layers.

Basal layer- the lowest one. The division of one row of cells in this layer forms the upper layers of the epidermis. The basal layer contains cells that produce the pigment melanin, the amount of which determines the color of the skin.
Layer spinosum consists of 5-15 rows of cells connected by processes, between which fluid circulates, nourishing the epidermis.
Granular layer. One or two rows of cells in this layer contain grains of keratohyalin (the protein substance that forms keratin - the horny substance of the skin).
Shiny layer from one or two rows of cells containing an intermediate product of the conversion of keratohyalin to keratin.
Stratum corneum- the topmost layer of the epidermis. It consists of keratinized cells and is relatively resistant to external influences.

The epidermis is a layer that is constantly renewed. The complete renewal period takes about 28 days.

Under the epidermis is dermis. The thickness of this layer is about 2 mm. The dermis consists of connective tissue containing a network of collagen and elastic fibers, hair follicles, blood vessels, pigment cells, sweat and sebaceous glands. The main structural protein of the dermis is collagen.

Skin nutrition is provided by a developed network of blood and lymphatic vessels. The sensitivity of the skin to external irritants is due to the presence of a large number of nerve plexuses and endings in different layers of the skin.

Located under the dermis subcutaneous fat. It consists of loose connective tissue filled with fatty lobules.

Collagen is the foundation of healthy and youthful skin

The condition of the dermis depends on its structural protein - collagen, which is capable of retaining water. This property affects the nutrition of the skin with beneficial substances, thanks to which cells actively divide and renew, ensuring elasticity and smoothness of the skin. Over time, the saturation of collagen with water decreases. This process begins at about 30 years of age. And under the influence of negative factors, such as city smog, smoking, unhealthy diet, stress, computer radiation, etc. - even earlier. After conducting research, experts found that the process of binding water in collagen is hampered by calcium, hydrogen and heavy metal ions accumulating in the dermis. Dehydration of collagen leads to a deficiency of internal cell nutrition and, as a result, to a visible deterioration in the condition of the skin: thinning, dullness, the formation of wrinkles, as well as a decrease in its protective properties and the appearance of pimples and comedones. However, scientists have found that the process of collagen dehydration is reversible. If excess harmful substances are removed from the dermis, collagen is filled with water again, cells receive adequate nutrition, and their active division begins. Skin condition improves. It is moisturized, wrinkles are smoothed out, the surface is leveled, foci of infection and inflammation disappear.

So, in order to restore the process of water binding in collagen, you need to cleanse the dermis of harmful hydrogen ions, calcium, and heavy metals. Specialists of NPL "LN-Cosmetics" have created a unique cosmetic product Lithocomplexes "Secret of Beauty", which effectively deeply cleanses the skin and promotes the synthesis of young collagen. The process of water binding in collagen is restored, skin cell nutrition is improved, blood flow and lymph movement are activated. After restoring the functioning of natural processes, the condition of the skin improves, it gains health and beauty!

The skin covers the entire human body and is the largest organ of the human body, which has various functions and is closely related to the entire body.

The importance of human skin is enormous. It is the human skin that directly perceives all environmental influences.

First, the skin reacts to any negative impact, and only then the whole body. The surface of the skin contains numerous folds, wrinkles, grooves and ridges, forming a characteristic relief that is highly individual and persists throughout life.

♦ About 70% of human skin is water and 30% is proteins (collagen, elastin, reticulin), carbohydrates (glucose, glycogen, mucopolysaccharides), lipids, mineral salts (sodium, magnesium, calcium) and enzymes.

♦ People have different heights, fatness, and, accordingly, skin area It will differ for different people, but on average this figure is at the level of 1.5-2.5 m2.

The weight of multi-layered skin is over 11-15 percent of a person’s weight.

♦ Skin function. Its main function is protective.

protective function from overheating of the body and mechanical damage, from radiation, including the ultraviolet part of the light spectrum, from microbes and harmful substances;
function of regulation through the sweating mechanism of equilibrium in the amount of water, the presence of certain substances;

through the skin, the body and the external environment exchange necessary substances; the skin, to some extent, is an auxiliary respiratory organ;
When certain conditions are created, the skin can serve as a synthesizer of useful substances. For example, when sunlight hits the skin, complex processes occur that contribute to the synthesis of vitamin D. From this point of view, tanning is useful, but we should not forget about the destructive properties of ultraviolet rays for all living cells.
tactile function: receptors are built into the skin, due to them a person has a sense of touch;
appearance shaper function: features of facial skin and subcutaneous facial muscles allow you to visually distinguish one person from another and convey your emotions.

♦ Skin structure. The skin consists of three layers, the top layer is the epidermis, the middle layer is the dermis and the bottom layer is the hypodermis (subcutaneous fatty tissue).

Epidermis

The epidermis is approximately 10.03-1 mm thick. Every three to four weeks, this layer of skin is renewed, this happens thanks to the deepest layer of the epidermis - the basal layer, in this layer of creatine - a very important protein for the skin - new cells are formed. Over the course of several weeks, these cells rise to the surface of the epidermis. By the end of their journey, they become dry, flat and lose their cell nucleus.

The epidermis or outer layer covers the dermis and is the surface of the skin with ridges and depressions and contains approximately 15 layers. This is the epithelium, constantly created by a layer of basement membrane. The epidermis is divided into 3 layers. The outer or stratum corneum, tough and impervious to water, consists of dead cells that are constantly separated from the epidermal layer by small scales under the action of new cells originating from the inner layers. The middle layer of the epidermis contains adult (squamous) cells that renew the outer layer. The middle layer or basement membrane layer creates new cells, which usually develop into squamous cells. The basement membrane layer also contains melanocytes, cells that create the pigment melanin. Exposure to the sun stimulates the formation of melanin to protect the skin. This is why a tan appears after exposure to the sun. Some artificial tanning creams stimulate the formation of melanin, others contain an ingredient (dihydroxyacetone) that gives the skin a red-brown color similar to a tan.

Dermis

The dermis is the main layer of the skin. The dermis is rich in connective fibers (75% of the structure), which maintain the elasticity (elastin) and resistance (collagen) of the skin. Both substances are extremely sensitive to sunlight (ultraviolet) rays, which destroy them. Cosmetics based on elastin and collagen cannot restore them because their molecules are too large and cannot penetrate the outer skin. The dermis contains receptors that perceive various external stimuli.

Hypodermis

This layer includes adipose tissue, subcutaneous nerve and vascular channels. The hypodermis also contains hair follicles and sweat glands.

♦ Color of the skin, gender and racial characteristics are possible due to the distribution of four main components on the surface of the skin:
- melanin, a brown pigment - carotene, the color of which varies from yellow to orange
- oxyhemoglobin: red
- carboxyhemoglobin: purple

Skin color is influenced by genetic factors, environment (sun exposure) and dietary factors. The complete absence of the first two pigments causes albinism.

♦ Freckles most often appear in adolescence and almost disappear by the age of 30. They don't turn dark by accident.

The presence of freckles means that the level of melanin in the human body, a photoprotective pigment, will decrease. That is, freckled skin is most vulnerable to harmful ultraviolet radiation. Therefore, people with freckles are strictly recommended to apply protective cream and avoid wearing too revealing clothes.

♦ Skin thickness varies depending on the areas considered from 0.5 mm to 2 mm on the palm and sole.

A baby's skin thickness is one millimeter. As you get older, it remains thin only on the eyelids. In an adult, the average skin thickness increases several times.
Leather has significant resistance to stretching.
The thinnest skin is on the eyelids and eardrums - from 0.5 mm and thinner, but the thickest is located on the feet, here it can reach a thickness of about 0.4-0.5 cm.

♦ Nails and hair also relate to the skin - they are considered its appendages.

♦ The skin has about 150 nerve endings, approximately 1 kilometer of blood vessels, more than 3 million cells and about 100-300 sweat glands.

♦ Vascular system The skin contains a third of all the blood circulating in the body - 1.6 liters. The skin tone also depends on the condition of the capillaries (whether they are dilated or narrowed) and their location.

♦ Sweat glands act as a temperature regulator.

In approximately every square centimeter of human skin there are about a hundred sweat glands, 5 thousand sensory points, six million cells, as well as fifteen sebaceous glands.
Their total number is from two to five million, most of these glands are located on the palms and feet, approximately 400 per square centimeter, followed by the forehead - about three hundred per square centimeter.
Asians have fewer sweat glands than Europeans and Africans.
Human skin produces about 1 liter of sweat per day.

♦ Skin cells there are from 300 to 350 million in the body. Over the course of his life, each person loses up to hundreds of kilograms of horny scales, which turn into dust.

The body must produce more than 2 billion skin cells per year. The fact is that in a year all skin cells are replaced at least 6 times (a complete replacement takes 55-80 days). The process of completing the cell cycle occurs at a rate of 0.6 million horny scales/hour (this amount corresponds to a weight of 0.7-0.8 kg).
In a person's entire life renews skin about 1000 times.
The skin that a person sheds over a lifetime weighs up to 18 kilograms.
Skin cells renew themselves more and more slowly with age: in newborns every 72 hours, and in people from 16 to 35 years old only once every 28-30 days.

♦ In one day sebaceous glands skin produces approximately 20 grams of sebum. After which the lard is mixed with sweat and forms a special film on the skin, which protects it from fungal and bacterial damage.

The number of sebaceous glands depends on the area of the body. There are few of them on the back of the hands, but on the T-zone of the face (forehead - wings of the nose - chin), under the hair on the head, in the ears, as well as on the chest and between the shoulder blades, there can be from 400 to 900 per 1 sq. cm. This is where pimples and so-called blackheads appear - comedones, by which a clogged pore can be identified.

♦ On the surface of the skin there are colonies of beneficial microorganisms that help in the fight against pathogenic bacteria.

If you achieve absolute sterility, you can weaken the double protection: excessive sterility is harmful to the skin.

For one sq.cm. skins account for 30,000,000 different bacteria.

♦ On average, there are from 30 to 100 moles on the skin of an adult, but sometimes their number can exceed 400. British scientists saw this as a connection with the speed at which the body ages.

According to the results of the study, the number of moles is proportional to the length of telomeres - the end fragments of chromosomes that shorten with each cell division. There is a hypothesis that people with many moles are less likely to suffer from age-related diseases.

♦ Skin ages due to ultraviolet radiation, stress, lack of sleep, reduction of collagen and fibroblasts.

♦ The smoothness of the skin depends on the condition collagen. In a young body, its cells are twisted, making the surface of the skin more taut and smooth. With age, due to lack of nutrition and poor water, collagen cells are filled with heavy metals and become straightened, and skin tone decreases.

Collagen makes up 70% of the dry dermis and decreases by 1% every year.

♦ Vascular mesh or stars can occur if there is a lack of vitamin D in the body, this disease occurs in 90% of people, so good skin requires good nutrition.

♦ Waterproof leather provides its outer layer of epidermis. Its cells are in very close contact with each other and have a layer of fat on the outer surface.

If the body is in water for a long time, the extracellular layer of fat becomes thinner and the water gains access to the skin cells, as a result it swells. We saw how in the water skin wrinkles your fingers? This transformation serves to improve traction (just like the treads in car tires).

♦ Loose skin syndrome- a rare connective tissue disease in which the skin easily stretches and forms loose folds.

In lax skin syndrome, the elastic fibers are mainly affected. The disease is usually hereditary; in rare cases and for unknown reasons, it develops in people with no precedent in the family.
Some hereditary forms are quite mild, while others are accompanied by some degree of mental retardation. Sometimes the disease leads to death.

When the skin is flaccid, flabby, it easily folds and has difficulty returning to its previous position.

In hereditary forms of the disease, excess skin folds already exist at birth or form later. "Excess" and laxity of skin is especially evident on the face, so that the sick child has a "mournful" appearance. A hooked nose is typical.
In general, lax skin syndrome is a connective tissue pathology.

Since connective tissue is part of all body systems, the manifestations of the syndrome are very diverse. The osteoarticular, pulmonary, cardiovascular, and digestive systems are affected.
No treatment has been developed. In people with a hereditary form of the disease, reconstructive surgery significantly improves appearance. However, excess skin may form again. Reconstructive surgery is less successful in the case of an acquired form of the disease.
Based on materials from videoplastica.ru, popular-medicine.rf

Health

1. Skin – largest organ in the human body

2. If you stretch the skin of an average person, it will cover an area of 2 square meters

3. Leather is approx. 15 percent of your body weight.

4. There are two types of skin: hairy and hairless

5. Your skin has three layers:

Epidermis - water-repellent and dead layer

Dermis – hair and sweat glands

Subcutaneous fat - fat and large blood vessels

6. Every inch of your skin has a certain elasticity and strength, depending on its location. So the skin on your knuckles is different from the skin on your stomach.

7. Scar tissue lacks hair and sweat glands

8. The thinnest skin on your eyelids - about 0.2 mm

9. The thickest skin on your feet - about 1.4 mm

10. In humans an average of 100,000 hairs per head. People with blond hair have about 140,000 hairs, dark-haired people have 110,000, and red-haired people have about 90,000.

11. Each hair has a small muscle that lifts the hair in cold and various emotional states

12. Body hair grow 2 to 6 years

13. We we lose from 20 to 100 hairs per day

14. Keratin forms the outer dead layer of skin and nails

15. More 50 percent of house dust is dead skin

16. Every 28 days your skin renews itself.

17. Lipids are natural fats that keep the outer layer of skin hydrated and healthy. Detergents and alcohol destroy lipids.

18. Skin loses more than 30,000 dead cells every minute

19. As we age, we begin to shed skin less often. In children, old cells are shed faster. This is why babies have such a pink, fresh complexion

20. The skin produces about 500 ml of sweat per day.

21. Sweat itself has no odor, and it is thanks to bacteria that body odor appears.

22. Your skin is a microcosm in which more than 1000 species of bacteria live and about 1 billion individual bacteria.

23. The glands that produce earwax are special sweat glands.

24. On average, you have about 14 types of fungi.

Melanin pigment and human skin color

25. Skin color is the result of the action of a protein called melanin. Huge tentacle-shaped skin cells - melanocytes - produce and distribute the pigment melanin.

26. People have the same number of melanin cells. Different skin colors are a result of their activity, not quantity.

27. Human skin varies greatly in different parts of the world. According to the well-known classification - the Lushan scale, there is 36 main types of human skin color.

28. 1 in 110,000 people are albino, that is, he does not have melanin cells.

29. Melanin is also responsible for eye color, and the skin covering the eye is transparent and very sensitive.

30. A child’s permanent skin color is formed within about 6 months.

Acne and skin treatment

31. The cause of acne or pimples is the excessive production of cells lining the sweat glands.

32. Even kids suffer from acne. Some newborn babies develop acne in the first few weeks of life. The cause of newborn acne is not fully known, but it does not require treatment and goes away on its own.

33. About 80 percent or 4 out of 5 teenagers experience acne.

34. But this is not only a problem of adolescence. One in 20 women and one in 100 men suffer from acne in adulthood

35. The appearance of a boil is associated with staphylococcal bacteria. It penetrates tiny cuts in the skin and enters the hair follicles.

Appearance of human skin

36. Skin appearance and texture talks about your health. When you are sick, your skin turns pale, and when you are tired, bags appear under your eyes.

37. Smoking negatively affects the condition of the skin, depriving it of oxygen and nutrients, slowing blood flow, and also contributing to the appearance of wrinkles.

38.Leather heals very quickly. Since the top layer of skin is living tissue, the body begins to heal the wound immediately. The blood from the cut forms a scab and seals the wound.

39. Most moles are genetically predetermined even before we are born.

40. People with more moles on their body live longer and look younger those who have fewer moles.

41. Almost every person has at least one mole.

42. Moles can appear anywhere, including the genitals, scalp and tongue.

43. Freckles most often appear in people with light skin color.

44. Freckles fade in winter, since melanin is not produced in large quantities during the winter months.

45. Freckles can be red, yellow, light brown and dark brown.

46. Unlike moles, Freckles do not appear at birth, they appear after a person has been exposed to sunlight.

47. Vitamin A treats skin damaged by sun exposure and cellulite

48. Vitamin D– reduces rashes and neoplasms

49. Vitamin C– antioxidant, restores vitamin E and protects from the sun

50. Vitamin E– Antioxidant, protects against sun damage and aging.

Older people and children have thinner skin than adults. In children in the first months of life, the average skin thickness is 1 mm; at the age of 3 to 7 years – 1–1.5 mm; from 7 to 14 years – 1.5–2 mm and only by 20–25 years it reaches 3 mm.

The skin in the area of natural openings (nose, mouth, vagina, anus, urethra) passes into the mucous membrane.

The skin consists of 3 layers:

1) upper - epidermal or epidermis;

2) the skin or dermis itself;

3) subcutaneous fat.

The epidermis is represented by stratified squamous keratinizing epithelium. Due to the ability to keratinize, or keratinize, the main cellular element of the epithelium is called a keratinocyte. There are five layers of cells in the epidermis, each of which represents a certain stage of differentiation (development) of keratinocytes.

The deepest layer, the basal or germinal layer, borders the dermis and consists of a single row of cells. In the cytoplasm of the keratinocyte, i.e. intracellularly, there are granules of dark brown or black pigment - melanin. In fair-skinned people, the pigment melanin is found only in the cells of the basal layer. In dark-skinned individuals, it occurs both in the cells of the stratum spinosum and in the stratum corneum. The basal layer also contains melanocytes, which make up about 10–25% of the cells in the basal layer and produce the pigment melanin. The ratio of melanocytes to keratinocytes in the epidermis is 1: 36. Black people and white people have approximately the same number of melanocytes. Melanin is involved in wound healing processes and protects body cells from the damaging effects of ultraviolet radiation.

Among the basal (main) keratinocytes there are tactile cells - Merkel cells (Merkel discs). There are especially many Merkel cells in the basal layer of the fingertips and lips. Langerhans and Greenstein cells, or immune cells, work together to regulate immune responses in the skin. Langerhans cells are capable of phagocytosis: by capturing foreign antigens and holding them on the surface, they provide immunological memory. Langerhans cells can synthesize biologically active substances: γ-interferon, interleukin-1, etc. Langerhans cells secrete met-enkephalin, an endogenous modulator (internal pathogen) of pain and a strong stimulator of the immune system. Above the basal layer is the spinous layer. Then the granular layer is located. On the palms and soles, the granular layer consists of 3–4 rows; in other areas, this layer is represented by 1–2 rows of cells. The cells of the granular layer have lost the ability to divide.

Flattened, anucleated keratinocytes form a stratum lucidum consisting of 3–4 rows of cells. The shiny layer is clearly visible on the skin of the palms, where the epithelium is thick. The cells of the stratum lucidum contain eleidin, glycogen, and oleic acid. The boundaries of the cells of the stratum pellucida are poorly visible.

The nonnuclear outer part of the epidermis is the stratum corneum. The thickest stratum corneum is on the skin of the palms and soles, on the extensor surface of the limbs. Thinner is the stratum corneum on the abdomen, on the flexor surface of the limbs, on the lateral surfaces of the body, especially thin on the skin of the eyelids and external genitalia in men. The stratum corneum is represented by horny plates (scales, corneocytes) - cells that are at the final stage of keratinization (keratinization). The horny plates in the outer part of the epidermis are gradually rejected. This process is called epithelial desquamation. Horny scales come in two types: with loose and dense filling of keratin fibrils (fibers). Loose horny scales are located closer to the granular layer, in them you can find the remains of cellular structures (mitochondria, etc.); these scales are called T cells. Dense horny scales are located superficially. The thickness of the stratum corneum depends on:

1) on the speed of reproduction and movement in the vertical direction of keratinocytes;

2) on the speed of their rejection.

The entire process of skin renewal, i.e., the appearance, differentiation, and maturation of keratinocytes, takes about 26–27 days. The main characteristics of the epidermis are shown in Table 2.

Skin is the largest organ of the human body, which has a complex structure and performs a number of vital functions. This is the most open and unprotected part of the human body, especially the skin on the face. The condition of the skin, like a mirror, is reflected not only by unfavorable external factors, but also by age, diet, and bad habits. Therefore, our main task is to carefully and systematically, and not to take care of it from time to time. In order for skin care to be reasonable and competent, first of all you should get acquainted with its structure and functions, and also learn to determine your skin type.

There are three layers of skin, the total thickness of which is only a few millimeters. All of them are penetrated through and through by many blood vessels, nerve fibers, sebaceous and sweat glands, and hair follicles.

So, the outer layer, or epidermis, form layers of epithelial cells that lie on top of each other. The upper layer, or the so-called stratum corneum, directly interacts with external factors. It consists of dead skin cells that rise to the surface of the skin from the deeper layers, thereby making room for young cells. The stratum corneum protects our body from penetration of microbes and foreign substances, and also retains moisture. A hydrolipid protective mantle helps him in this. It is a thin film located on the surface of the skin. It consists of sweat particles, sebaceous gland secretions and viscous substances that connect individual keratinized cells. It is a kind of natural skin cream with an acidic chemical environment that kills fungi and bacteria.

The epidermis is also responsible for the appearance of tanning, since in its deepest layer the pigment melanin is produced by special cells - melanocytes. It regulates the intensity of tanning and skin color. The amount of melanin depends on the degree of exposure to ultraviolet rays, as well as on the genetic predisposition of the body. The number of melanocytes is approximately the same in all people.

Under the epidermis is dermis, or the skin itself. It includes two layers: papillary and reticular. Their total thickness is approximately 2-2.5 mm. This is a kind of skin frame that maintains its elasticity due to collagen and elastin fibers. The main difference between the layers of the dermis is the structure of the fibers. In the papillary layer they are thinner and more mobile, and in the reticular layer they are denser. Collagen fibers give the skin strength and have the ability to renew. But elastin fibers, which are responsible for skin elasticity, are not restored, which leads to the appearance of wrinkles and sagging skin. The space between the fibers is filled with aqueous gel. This is a viscous substance, most of which is hyaluronic acid.

It should be remembered that the fibers have a certain direction. Therefore, during facial treatments, in particular when applying cream or massage, it is necessary to strictly follow the massage lines. This will help avoid premature loss of elasticity of the fibers, and therefore premature aging of the skin.

The reticular layer also contains sebaceous, sweat glands and hair follicles. Secretions of the sebaceous and sweat glands create additional protection against microorganisms. However, this protective film is easily destroyed when using alkaline products such as soap. Therefore, it is better to cleanse the skin using special products that effectively remove impurities and at the same time do not wash away the natural acid barrier of the skin.

The dermis, unlike the epidermis, is permeated through and through with nerve endings, muscles and receptors. It also contains blood vessels that carry nutrients and oxygen to the top layer of the skin and give it a pleasant pink tint.

The third, deepest layer of skin is hypodermis, or subcutaneous fatty tissue. It is a connective tissue consisting of cells - fat cells. Directly below it is the muscle layer.

The hypodermis has three main functions:

❧ protects internal organs from damage;

❧ helps regulate body temperature,

❧ protecting it from overheating and hypothermia; makes skin smooth and soft.

The thickness of the fat layer is not the same for all women and depends on both genetic predisposition and lifestyle. It is worth noting that the hypodermis is practically absent on the lips; it is completely absent on the eyelids. Therefore, these areas of the face require especially careful care.