Beautiful and well-groomed skin can become a real pride, because people are used to evaluating it, first of all, in terms of aesthetics. Meanwhile, it is an important organ that performs many functions in our body. Find out what is the structure of the skin and its role in our lives.

Briefly about the properties of the skin

Human skin has unique properties. With a total surface area of ​​about 2 sq.m and a thickness of 1-4 mm, it is the largest organ of the body. Leather is resistant to heat and cold. She is also not afraid of water, acids and alkalis, unless they have very high concentrations. The skin remains soft, flexible and resistant to stretching, even if it has been exposed to adverse weather conditions or other external influences for a long time. Its strength helps to perfectly protect internal tissues and organs.

Through a complex system of receptors connected to the brain, the skin provides detailed information about the state of the environment and ensures that our body will adapt to external conditions.

The skin consists of three main layers - the epidermis, dermis and subcutaneous tissue.

Epidermis

The epidermis is the outer layer, which is formed by stratified squamous epithelium. Its surface consists of keratinized cells that contain keratin. The epidermis is used mainly for protection against mechanical irritants and chemical agents and has 5 layers:

• the basal layer (located deeper than the other layers, also called the germ layer due to the fact that mitotic division and proliferation of keratinocytes take place in it);


• spiny layer - several rows of polygonal cells, between which there is a space filled with desmoglein;


• granular layer - consists of cells whose nuclei are filled with keratohyalin granules, an important intermediate in the production of keratin;


• shiny layer - located in places where the skin is subject to active mechanical influences (on the heels, palms, etc.), serves to protect the deep layers;


• stratum corneum - contains the protein keratin, which has the ability to bind water, due to which our skin acquires elasticity.

Deep layers (basal, spiny, granular) have the ability to intensive cell division. Produced new epidermal cells regularly replace the upper stratum corneum. The correct process of keratinization and exfoliation of dead cells of the epidermis is called keratosis. If keratinization in the skin is too intense, in this case we are talking about hyperkeratosis. There is also dyskeratosis, or insufficient keratosis, and parakeratosis - abnormal keratinization and transformation of the upper layer.

The epidermis also contains cells whose function is to prepare the melanin pigment. It is he who gives the skin and hair color. Under the influence of an increased amount of ultraviolet light, the production of melanin increases (which gives the effect of a tan). Excessive and too intense sun exposure, however, can damage the deeper layers of the skin.

Dermis

The dermis is the middle layer of the skin, which has a thickness of 1 to 3 mm (depending on the location on the body). It consists mainly of fibers of connective and mesh tissue, thanks to which our skin is resistant to compression and stretching. In addition, the dermis has a well-developed vascular network and a network of nerve endings (thanks to which we feel cold, heat, pain, touch, etc.). The dermis is made up of two layers:

1. The papillary layer - this includes the dermal papillae, which contain a number of small blood vessels (papillary tissue). The dermal papillae also contain nerve fibers, sweat glands, and hair follicles.


2. The reticular layer lies above the subcutaneous tissue and has a large amount of collagen fibers and connective tissue. There are deep vascular plexuses between the dermis and subcutaneous tissue, but the reticular layer practically does not contain capillaries.

Connective tissues in the dermis are represented by 3 types of fibers: collagen, smooth muscle and elastic.

Collagen fibers are created by the protein collagen (it belongs to the group of scleroproteins) and are an important component - thanks to collagen fibers, our skin is elastic. Unfortunately, as we age, the production of collagen fibers decreases, so the skin sags (wrinkles appear)

Elastic fibers - got their name due to the ability to reversibly stretch. They protect collagen fibers from excessive stress.

Smooth muscle fibers - lie near the subcutaneous tissue and are created by an amorphous mass of mucopolysaccharides, which include hyaluronic acid and protein complexes. Thanks to smooth muscle fibers, our skin takes important nutrients from the subcutaneous layer and transfers them to different layers.

Subcutaneous tissue

This is a deep layer of the skin, which, like the previous ones, is formed by connective tissue. Subcutaneous tissue contains numerous groups of fat cells, from which subcutaneous fat is formed - an energy material used by the body depending on demand. Subcutaneous fat also protects organs from mechanical stress and provides thermal insulation for the body.

Skin appendages

Human skin has the following adnexal formations:

• hair;


• nails;


• sweat glands;


• milk glands;


• sebaceous glands.

Hair are flexible and elastic horny fibers. They have a root (located in the epidermis) and the body itself. The root is embedded in the so-called hair follicle. Initially, human hair served as a protection against heat loss. Currently, their intensive growth is observed only on the head, in the armpits and near the reproductive organs. There are residual hairs in other parts of the body.

Nails - horny plates that perform a protective function for the fingers.

Sweat glands - have a tubular shape and are located in the dermis and subcutaneous tissue. There are 2 types of sweat glands:

• eccrine glands - present on the entire surface of the skin and are involved in thermoregulation, releasing sweat;


• apocrine glands - present in the genital area, anus, nipples and armpits, their activity begins after puberty

Sebaceous glands are vesicular glands that have a single or branched structure. They lie in close proximity to the hair. Thanks to the sebaceous glands, the skin and hair are lubricated, as a result of which they become more elastic and resistant to drying out.

The mammary glands are developed in women and are necessary for the production of milk.

Skin functions

The human skin performs many different functions. We divided them into passive and active.

Passive Features:

• protection from cold, heat, radiation;


• protection against pressure, impact, friction;


• protection against chemicals (skin has a slightly acidic pH);


• protection against germs, bacteria, viruses, fungi (due to the fact that the top layer is constantly peeling off and being renewed).

Active features:

• fight against pathogenic microbes in the skin (phagocytes, immune system);


• thermoregulation (sweat, the nervous and vascular systems of the skin are controlled by signals from

» Hyperkeratosis and acne
» Comedogenic cosmetics and acne
» Demodex subcutaneous mite
» Propionibacterium acnes and Propionibacterium granulosum
» Irritated skin and acne
» Heredity and acne
» Nutrition and acne
» Medicines and acne
» Steroids and acne

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Skin is a tissue: elastic, porous, durable, waterproof, antibacterial, sensitive, which can maintain heat balance, protect against the harmful effects of the external environment, secrete fat, preserve the skin, produce odorous substances and recover (regenerate), as well as absorb some necessary chemical elements and reject others, protect our body from the adverse effects of sunlight.

The pH of human skin is 3.8-5.6.

There are approximately 5 million hairs on the surface of human skin. For every square centimeter of human skin, there are an average of 100 pores and 200 receptors.

Which layers of the skin can be affected by cosmetics?

Since cosmetic (cosmeceutical products) can penetrate deeply, can cosmetics reach the dermis?

According to the laws of most countries, a cosmetic product can only have an external effect. This means that no cosmetic additives should reach the living layers of the skin and act on them. Cosmetic preparations can and must interact only with the dead substances of the skin and under no circumstances should reach its living layers and, moreover, affect them. That is the purpose of cosmetics.

However, in the lower part of the epidermis there is no "shutter" that prevents the penetration of substances into the depths of the dermis (into the blood and lymphatic vessels). The presence of an effective exchange between the epidermis and dermis is confirmed by experimental data. Substances that have overcome the transepidermal barrier, with a certain degree of probability, enter the bloodstream and, in accordance with this, are able to affect all tissues of the body.

What substances are able to penetrate deep into the skin, overcome the transepidermal barrier and enter the dermis?

It has been proven that the following penetrate deep into the skin: nicatin, caffeine, nitroglycerin, essential oils (they are enhancers, they are found in the bloodstream), vitamin E lingers at the junction of the epidermis and dermis, hyaluronic acid reaches the dermis 30 minutes after application, and then enters into the blood (source: Journal of Investigative Dermatology). Scientists from the University of Rochester Medical Center have concluded that the nanoparticles that make up sunscreens penetrate deep into the skin. Liposomes are nanoparticles that easily penetrate into the deeper layers of the skin and deliver the necessary nutrients there.

Structure of the Skin

The secret of the amazing multifunctionality of the skin lies in its structure. The skin is made up of 3 important layers:

• 1. The outer layer is the epidermis,
• 2. The inner layer is the dermis,
• 3. Subcutaneous base - hypodermis.

Each layer performs a specific function.

In different parts of the body, the thickness and color of the skin, the number of sweat, sebaceous glands, hair follicles and nerves are not the same.

It is believed that the skin is only a few millimeters thick, but if the skin constantly needs protection, then it becomes thicker, this is a defense mechanism that everyone has. Therefore, in some places the skin is thicker, in others thinner. The soles and palms have a denser epidermis and a layer of keratin.

As for hairiness, for example, there are many hair follicles on the top of the head, but none on the soles. The tips of the fingers and toes contain many nerves and are extremely sensitive to touch.

The structure and properties of human skin: Epidermis

The epidermis is the upper stratum corneum of the skin, which is formed by stratified epithelium. In the deep layers of the epidermis, the cells are alive, there they divide and gradually move to the outer surface of the skin. At the same time, the skin cells themselves die and turn into horny scales, which are peeled off and removed from its surface.

The epidermis is practically impermeable to water and solutions based on it. Fat-soluble substances penetrate the epidermis better due to the fact that cell membranes contain a large amount of fats and these substances seem to “dissolve” in cell membranes.

There are no blood vessels in the epidermis, its nutrition occurs due to the diffusion of tissue fluid from the underlying layer of the dermis. The intercellular fluid is a mixture of lymph and blood plasma flowing from the terminal loops of the capillaries and returning to the lymphatic and circulatory systems under the influence of heart contractions.

What cells make up the epidermis?

Most epidermal cells produce keratin. These cells are called keratinocytes (spiky, basal, and granular). Keratinocytes are in constant motion. Young keratinocytes are born during the division of the germ cells of the basement membrane, located at the border of the epidermis and dermis. As they grow older, the keratinocyte moves to the upper layers, first to the spiny layer, then to the granular one. At the same time, keratin, a particularly strong protein, is synthesized and accumulated in the cell.

Eventually, the keratinocyte loses its nucleus and major organelles and turns into a flat "pouch" stuffed with keratin. From that moment on, it receives a new name - "corneocyte". Corneocytes are flat scales that form the stratum corneum (obsolete cells of the epidermis) responsible for the barrier function of the epidermis.

The corneocyte continues to move up and, having reached the surface of the skin, exfoliates. A new one takes its place. Typically, the life span of a keratinocyte lasts 2-4 weeks. In childhood, the process of renewal of epidermal cells is more active, and slows down with age.

Corneocytes are held together by a plastic "cement" consisting of a double layer of special lipids - ceramides (ceramides). molecules ceramides (ceramides) and phospholipids have hydrophilic "heads" (fragments that love water) and lipophilic "tails" (fragments that prefer fats).

Melanocytes are found in the basal layer of the skin (basement membrane) and produce melanin. These are the cells that produce the pigment melanin, which gives skin its color. Thanks to melanin, the skin protects a person to a large extent from radiation: infrared rays are completely blocked by the skin, ultraviolet rays are only partially. In some cases, the formation of age spots depends on the state of the basement membrane.

There are in the epidermis and special Langerhans cells, which perform the function of protection against foreign bodies and microbes.

What is the thickness of the epidermis?

The thickness of the epidermis is approximately equal to 0.07 - 0.12 millimeters (this is the thickness of a plastic film or paper sheet), the especially rough skin of our body can reach a thickness of 2 mm.

The thickness of the epidermis is heterogeneous: in different places of the skin it is different. The thickest epidermis, with a pronounced keratinized layer, is located on the soles, a little thinner on the palms, and even thinner on the genitals and skin of the eyelids.

How many days does the complete renewal of the epidermis take?

The appearance of the skin, its freshness and color depend on the condition of the epidermis. The epidermis consists of dead cells, which are replaced by new ones. Due to the constant renewal of cells, we lose about 10 billion cells a day, this is a continuous process. During a lifetime, we shed about 18 kilograms of skin with keratinized cells.

When the skin is exfoliated, it is cleansed - this is a necessary process of skin renewal, in which, together with dead cells, all substances harmful to the skin are removed: the cells carry away dust, microbes, substances secreted by the sweat glands (urea, acetone, bile acids come to the surface along with sweat). pigments, salts, toxic substances, ammonia, etc.). and much more. The skin does not allow the army of microbes to reach us: during the day, our skin is attacked by 1 cm from 100 thousand to several million of all kinds of microbes. However, if the skin is healthy, it becomes impervious to them.

The younger and healthier the skin, the more intense the process of its renewal. New cells push out old ones, old ones are washed away after we take a shower, wash, sleep, put on clothes. With age, cell renewal occurs less and less, the skin begins to age, wrinkles appear.

The epidermis is separated from the dermis by a basement membrane (it consists of elastin and collagen fibers) with a germ layer of continuously dividing cells, which gradually move from the basement membrane to the surface of the skin, where they then peel and fall off. The epidermis is completely renewed, exactly replaced by a completely new layer: a mole remains a mole, dimples remain dimples, freckles freckles, cells accurately reproduce at the genetic level how the skin should look in accordance with the individual characteristics of each individual person.

The process of cell movement from the basement membrane to peeling and falling off the skin surface at a young age is 21-28 days, and then it happens less and less. Starting at about 25 years of age, the process of skin renewal becomes slower and increases to 35-45 days by the age of 40 and 56-72 days after the age of 50. This is the reason for the use of anti-aging and restorative drugs for a period of at least a month, and for a more mature age - at least 2-3 months.

The process of division and advancement of mature skin cells is not only slow, but also heterogeneous in different areas, which also affects the aesthetic appearance of the skin. If dead skin cells build up, the process of cell division occurs more slowly, which leads to faster aging of the skin. In addition, the layering of dead cells makes it difficult for oxygen and nutrients to penetrate the skin.

How many layers does the epidermis contain?

The epidermis consists of 12-15 layers of the stratum corneum. However, depending on the structure, the epidermis can be divided into five main zones (layers): basal, prickly, granular, shiny and horny. The upper (outer) layer of the epidermis consists of already dead cells without nuclei, the inner one consists of living cells that are still capable of dividing.

Fragments of the stratum corneum, lustrous, and granular layers that do not have the ability to divide can be attributed to dead skin structures, and, accordingly, the boundary between "living and dead" substances should be located somewhere in the spinous layer.

1. Basal layer of the epidermis (growth)

The basal layer is the innermost layer of the epidermis closest to the dermis. It consists of a prismatic single-row epithelium and a large number of slit-like spaces.

The bulk of the cells here are keratinocytes containing chromatin and melanin.

Between the basal keratinocytes are melanocytes containing a huge amount of melanin. Melanin is formed in these cells from tyrosine in the presence of copper ions. This process is regulated by melanocyte-stimulating pituitary hormone, as well as catecholamines: adrenaline and norepinephrine; thyroxine, triiodothyronine and androgens. The synthesis of melatonin increases when the skin is exposed to ultraviolet radiation. Vitamin C plays a significant role in the synthesis of melanin.

Among the cells of the basal epithelium there are few specific tactile (Merkel) cells. They are larger than keratinocytes in size, contain osmiophilic granules.

The basal layer provides attachment of the epidermis to the underlying skin and contains cambial epithelial elements.

2. Spiny layer of the epidermis (stratum spinosum)

Above the basal layer is prickly (stratum spinosum). In this layer, keratinocytes are located in several layers.

The cells of the spinous layer are large, their shape is irregular, gradually becoming flattened when approaching the granular layer. The cells of the spiny layer contain spines at the sites of intercellular contacts.

In the cytoplasm of spiny cells there are keratinosomes - granules containing lipids - ceramides. The cells of the spinous layer secrete ceramides outward, which, in turn, fill the space between the cells in the layers above. Thus, the keratinized stratified squamous epithelium becomes impermeable to various substances.

In addition, there are also desmosomes - specialized cell structures.

Keratinocytes in the stratum spinosum contain very little chromatin, so they are paler. They have one feature: in their cytoplasm there are many special thin tonofibrils.

3. Granular layer of the epidermis (stratum granulosum)

The granular (keratohyalin) layer (stratum granulosum) consists of spiny keratinocytes and process epidermocytes. It is assumed that these cells are "wandering" epidermal macrophages that perform a protective function.

In the granular layer, there are from 1-3 on the palms and 5-7 on the soles of layers of flat cells, closely adjacent to each other. Their oval nuclei are poor in chromatin. A feature of the cells of the granular layer is the peculiar grains in their cytoplasm, consisting of a substance similar in structure to DNA.

There are two main types of granules located in the cytoplasm of cells of the granular layer: keratoglanic and lamellar. The former are necessary for the formation of keratin, and the latter provide moisture impermeability of the skin by releasing special lipid molecules on its surface.

4. Shiny (eleidine, transparent) layer of the epidermis (stratum lucidum)

The shiny layer (stratum lucidum) is above the granular layer. This layer is quite thin, and is clearly visible only in those areas where the epidermis is most pronounced - on the skin of the palms and soles.

It is not located on all areas of the skin, but only where the thickness of the epidermis is significant (palms and soles), and is completely absent on the face. Consists of 1-3 rows of flat cells, most of which do not contain nuclei.

Flat, homogeneous keratinocytes are the main cellular elements of this layer. The shiny layer is essentially a transition from living epithelial cells to keratinized scales located on the very surface of human skin.

5. The stratum corneum of the epidermis (stratum corneum)

The stratum corneum (stratum corneum) is the layer of the epidermis that is in direct contact with the external environment.

Its thickness varies in different parts of the skin, and very significantly. The most developed stratum corneum is on the palms and soles, much thinner on the abdomen, flexion surfaces of the arms and legs, sides, skin of the eyelids and genitals.

The stratum corneum has in its composition only thin non-nuclear cells that are tightly adjacent to each other. Horny scales consist of keratin - a substance of an albuminoid nature, containing sulfur in excess, but little water. The scales of the stratum corneum are tightly connected to each other and provide a mechanical barrier to microorganisms.

The structure and properties of human skin: Dermis

The dermis is the inner layer of the skin, the thickness of which is from 0.5 to 5 mm, the largest on the back, shoulders, and hips.

In the dermis there are hair follicles (from which hair grows), as well as a huge number of the thinnest blood and lymphatic vessels that provide nutrition to the skin, contraction and relaxation of blood vessels allows the skin to retain heat (thermoregulatory function). The dermis contains pain and sensory receptors and nerves (which branch into all layers of the skin and are responsible for its sensitivity).

In the dermis there are also functional glands of the skin, through which excess water and salts are removed (excretory function): sweat glands (produce sweat) and sebaceous glands (produce sebum). The sebaceous glands produce the necessary amount of sebum, which protects the skin from aggressive external influences: makes the skin waterproof, bactericidal (sebum, together with sweat, creates an acidic environment on the surface of the skin, which adversely affects microorganisms). Sweat glands help maintain a constant body temperature, preventing overheating by cooling the skin through sweat.

How many layers does the dermis contain?

The dermis includes two layers: the reticular and papillary layers.

The reticular layer consists of loose connective tissue. This tissue includes an extracellular matrix (we will talk about it in more detail below) and cellular elements.

The papillary layer protrudes into the epidermis and forms the skin papillae. These papillae create a special unique "pattern" of our skin and are especially visible on the balls of our fingers and the soles of our feet. It is the papillary layer that is responsible for "fingerprints"!

The basis of the cells in the dermis is fibroblast, which synthesizes extracellular matrix, including collagen, hyaluronic acid and elastin.

What is the extracellular matrix and what does it consist of?

The composition of the extracellular matrix includes two main components: the fibrillar part and the matrix.

fibrillar part- these are collagen, elastin, and reticulin fibers that create the skin frame. Collagen fibers are intertwined with each other, thus creating an elastic network. This network is located almost on the surface of the skin under the epidermis and makes up the skeleton, which gives the skin strength and elasticity.

In the face area, collagen fibers create a special dense network. The collagen fibers in it are so strictly stacked and ordered that they form lines of the least stretch. They are known as the Langer lines. They are known to cosmetologists and massage therapists: facial massage is performed along the Langer lines and any cosmetics are applied. This is done in order not to load the skin, not to stretch it, thus provoking the formation of wrinkles.

In youth, the framework of collagen fibers is strong and able to ensure the mobility and flexibility of the skin, maintaining its elasticity and shape. Unfortunately, our female age is short ...

I really liked the comparison of the skin with the Soviet bed, which is based on a metal mesh. The iron springs of the new bed quickly return to their original position, but from the load, the springs of the frame begin to sag and soon our bed loses its shape. Our skin also works - young springs (collagen fibers) keep their shape perfectly, but with age they sag and become flabby. Whatever great mattress we put on the surface, it will not solve our problem.

Matrix (matrix or amorphous component) its structure resembles a gel and consists of polysaccharides. The more famous polysaccharides are chitosan, seaweed polysaccharides, hyaluronic acid.

It is the components of the extracellular matrix, both amorphous and fibrillar, that create the skin from the inside. By themselves, saccharides do not form fibers, but they fill all the gaps between connecting cells and fibers. It is through them that the interstitial transport of all substances occurs.

As a result, it is the state of the dermis (water content in the polysaccharide gel, the integrity of collagen fibers, etc.) that determines the state of the epidermis and the healthy appearance of the skin.

The structure and properties of human skin: Hypodermis (subcutaneous fatty tissue)

The hypodermis is the subcutaneous base (fat layer), protects our body from excess heat and cold (allows us to retain heat inside us), acting as a thermal insulator, softens the fall from shock.

Subcutaneous adipose tissue - a storehouse of vitamins

Fat cells also represent a depot in which fat-soluble vitamins (A, E, F, K) can be stored.

Less fat - more wrinkles

Subcutaneous adipose tissue is very important as a mechanical support for the outer layers of the skin. The skin, in which this layer is weakly expressed, usually has more wrinkles and folds, and "ages" faster.

The more fat, the more estrogen

An important function of adipose tissue is hormone-producing. Adipose tissue is able to accumulate estrogens in itself and can even stimulate their synthesis (production). Thus, you can get into a vicious circle: the more subcutaneous fat we have, the more estrogen is produced. This is especially dangerous for men, since estrogenic hormones suppress their production of androgens, which can lead to the development of hypogonadism. This leads to a deterioration in the work of the gonads and leads to a decrease in the production of male sex hormones.

It is very important for us to know that adipose tissue cells contain a special enzyme - aromatase. It is with its help that the process of estrogen synthesis by adipose tissue is carried out. Guess where is the most active aromatase? That's right, in fatty tissue on the hips and buttocks!

What is responsible for our appetite and satiety?

Our adipose tissue contains another very interesting substance - leptin. Leptin is a unique hormone that is responsible for the feeling of satiety. Leptin allows our body to regulate appetite and through it the amount of fat in the subcutaneous tissue.

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

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

First, there is a reaction of the skin to any negative impact, and only then of the whole organism. The surface of the skin contains numerous folds, wrinkles, grooves and folds, forming a characteristic relief that is purely 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 height, fullness, respectively, and skin area different people will differ, but on average this figure is at the level of 1.5-2.5 m2.

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

♦ skin function. Its main function is protective.

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

• through the skin, the body and the environment exchange the necessary substances, the skin is to some extent an auxiliary respiratory organ;
• Under certain conditions, 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, sunburn is useful, but one should not forget about the properties of ultraviolet rays that are detrimental to 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 the skin of the face and subcutaneous mimic muscles allow you to visually distinguish one person from another and convey your emotions.

♦ The structure of the skin. The skin consists of three layers, the upper layer is the epidermis, the middle layer is the dermis and the lower 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 the skin is renewed, this is due to the deepest layer of the epidermis - the basal one, in this layer of creatine - a very important protein for the skin - new cells are formed. Within a few 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 bulges and depressions, includes approximately 15 layers. This is the epithelium, constantly created by the basement membrane layer. The epidermis is divided into 3 layers. The outer or stratum corneum, strong, impermeable to water, consists of dead cells, which 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 (scaly) 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, the cells that produce the melanin pigment. Sun exposure stimulates the production of melanin to protect the skin. That is why after exposure to the sun a tan appears. 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) that maintain the elasticity (elastin) and resistance (collagen) of the skin. Both substances are extremely sensitive to solar (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. In the dermis there are 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, sexual 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 affected by genetic factors, environment (sun exposure) and nutritional 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 darken randomly.

The presence of freckles means that in the human body it will reduce the level of melanin, a photoprotective pigment. That is, freckled skin is most vulnerable to harmful ultraviolet radiation. Therefore, people with freckles are strongly advised to smear with a protective cream and avoid too open clothing.

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

• In a baby, the thickness of the skin is one millimeter. As it grows older, it remains thin only on the eyelids. In an adult, the average value of skin thickness increases several times.
• The skin has a 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 belong to the skin - they are considered its appendages.

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

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

♦ sweat glands act as a temperature controller.

• Approximately in 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 releases about 1 liter of sweat per day.

♦ skin cells in the body, there are from 300 to 350 million. During his life, each person loses up to a hundred kilograms of horny scales, which turn into dust.

• In a year, the body must produce more than 2 billion skin cells. The fact is that during the year the change of all skin cells occurs at least 6 times (complete replacement - in 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).
• For a lifetime man renews the skin about 1000 times.
• The skin that a person sheds over a lifetime weighs up to 18 kilograms.
• Skin cells are renewed 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 that, the fat 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, and 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, they can be from 400 to 900 per 1 sq. cm. It is there that acne and the so-called black dots appear - comedones, by which you can identify a clogged pore.

♦ 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. skin accounts for 30,000,000 different bacteria.

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

♦ The skin is aging 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, which makes the surface of the skin more stretched and smooth. With age, from lack of nutrition and poor water, collagen cells are filled with heavy metals and straighten, and skin tone decreases.

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

♦ Vascular meshes or asterisks can occur if there is a lack of vitamin D in the body, this disease occurs in 90% of people, therefore good nutrition is necessary for good skin.

♦ Waterproof skin provides its outer layer of the 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 water gains access to the skin cells, as a result, it swells. We saw how in the water wrinkled skin your fingers? This transformation serves to improve traction (just like treads in car tires).

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

In flaccid skin syndrome, mainly elastic fibers are affected. The disease is usually hereditary; in rare cases and for unknown reasons, it develops in people who do not have precedents in the family.
Some hereditary forms are quite mild, others are accompanied by some degree of mental retardation. Sometimes the disease leads to death.

With sluggish, flabby skin, it easily gathers into folds and hardly returns to its previous position.

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

Since the connective tissue is part of all body systems, the manifestations of the syndrome are very diverse. Both the osteoarticular, and pulmonary, and cardiovascular, and digestive systems are affected.
Treatment has not been developed. In people with a hereditary form of the disease, reconstructive surgery significantly improves the appearance. However, excess skin can form again. Reconstructive surgery is less successful in the case of an acquired form of the disease.
According to videoplastica.ru, popular-medicine.rf

Habitually, the skin is considered from the point of view of its aesthetic qualities, often forgetting that it is a vital organ with a special structure and a whole range of functions. Its main purpose is to protect internal organs and tissues from the effects of negative environmental factors.

The histological structure of the skin explains its unique properties. Appearance and condition play an important role in the diagnosis of various disorders. The skin is studied not only by the section of anatomy - histology, but also by such areas in medicine as dermatology and cosmetology.

Soft, elastic fabric is resistant to temperature changes, various liquids, non-concentrated acids and alkalis. It is sensitive, but very durable, has a complex system of receptors that convey information to the brain about the state of the environment. One of its most important functions is aesthetic.

The salons offer a wide range of services through which it becomes possible to prolong youth and beauty. Only knowing the structural features of the skin, you can provide it with proper, high-quality care.

Human skin consists of three layers, which are subdivided into smaller ones. The surface layer of the skin is the epidermis. This is a kind of barrier between the body and the outside world. It protects the body from external influences, signals a malfunction in the functioning of internal organs, and requires careful attitude and proper care.

Most cosmetics on the market and cosmetic procedures are aimed at maintaining an attractive appearance of the epidermis. Its structure is very complex.

• The basal layer is located at the very bottom of the epidermis, adjacent to the dermis, consists of cells containing 70% water. New cells are formed here, which then rise to the upper layers. The basal or, as it is also called, the germ layer ensures the normal course of regenerative processes in the tissues of the epidermis.
• The spinous layer is formed from living cells with a nucleus, which look like small spikes under a microscope. Its main purpose is to launch the processes of keratin synthesis.
• The granular layer is the densest, here small cells are closely pressed against each other. They are responsible for moisturizing the skin, retain certain substances, secrete intercellular fat necessary for the connection of corneocytes. The granular, spiny, and basal layers are collectively referred to as the Malpian layer, as they are composed of living cells containing a nucleus.
• The shiny layer protects the skin from friction, wear, it consists of flat cells without a nucleus, is present only on the palms and soles.
• The stratum corneum of the skin consists of a large number of non-nuclear cornetocytes, in which metabolic processes do not occur. There is a connection between the cells that provides the skin with reliable protection from the negative influence of external factors.

The uppermost layer of the skin is a thin film consisting of small horny scales connected by intercellular lipids. The latter have powerful moisture-repellent properties, protect the skin from dehydration and liquid penetration from the outside. In the process of development, the cells of the stratum corneum lost their organelles and nucleus, turning into scales.

Cosmetics consist of substances alien to the body, therefore, upon contact with them, the outer layer of the skin weakens, which is fraught with loss of moisture and other unpleasant manifestations. High-quality care products can give the upper layer of the epidermis elasticity and firmness, and moisturize it.

Corneocytes or horny scales throughout their lives are subjected to mechanical stress, friction and other factors that do not affect them in the best way, they wear out and are replaced by new ones.

Features of the dermis

The dermis is the skin itself, protected by the epidermis. These two large layers are connected by a basement membrane. The structure of the dermis is organized in a special way. It contains lymphatic and blood vessels that provide proper nutrition to the cells.

The middle layer of the skin is formed from collagen fibers, which provide it with elasticity and the necessary rigidity, and elastin fibers - elasticity, the ability to stretch and return to its original position.

The interfiber space of the dermis is filled with a specific substance resembling a gel. Basically it is hyaluronic acid. It is responsible for retaining moisture in the cells. Human skin, that is, the dermis itself, consists of two layers.

• The papillary layer is a loose connective tissue, which was formed from elastic, reticular and collagen fibers. It contains follicles, from which hairs, sweat glands then grow. The difference of this layer of the dermis is that it has a complex vascular system, resembling a dense network of small capillaries. They diverge and unite, nourish the cells, saturate them with oxygen.
• The basis of the reticular layer is a dense connective tissue, consisting of fibroblasts and dermal melanocytes, which do not have the ability to synthesize melanin pigment. This ball of the dermis is intended to ensure the strength of the skin.

The structure of facial skin in cosmetology plays an important role, as it allows specialists to develop effective tools and techniques to provide high-quality, complete skin care, slow down age-related and destructive processes in it.

The cells of the dermis and epidermis under the influence of certain factors are damaged and replaced by new ones. Regeneration processes slow down with age, which causes the formation of wrinkles, irregularities, loss of contour definition and other defects.

The changes occurring in the epidermis, dermis and hypodermis are due to age-related features of the structure and functions of the skin. The older a person becomes, the slower the skin is renewed, damaged cells accumulate inside, which causes loss of firmness and elasticity.

Fat and muscle tissue

A special set of functions is performed by the lipid layer of the skin, consisting of fat cells. It is also called the hypodermis or subcutaneous adipose tissue. This is a supply of nutrients necessary for the normal functioning of the skin, a support for the dermis, a pantry of energy. And also this inner layer of the skin is involved in the synthesis of some sex hormones, softens the mechanical stress on the body, gives the forms elasticity, bulge.

The lipid layer is a tissue that consists of many small lobules, blood vessels pass inside it. Due to malnutrition, drinking alcohol, smoking, pathological processes in the body, this layer undergoes dystrophic changes (fat in the lobules accumulates in excess, the partitions thicken, inflammation and swelling may occur). This will definitely affect the appearance.

The structure of human skin is considered together with the musculoaponeurotic system. The structure of the facial skin contains muscles that provide facial expressions (change of expression, movement of lips, eyebrows, smile). Their feature is that they are not connected to bone tissue. The muscles are firmly attached to the skin, create heaviness, as a result of which the structure of the epidermis of the skin changes.

Today, the cosmetology market offers various services that involve the introduction of special preparations for muscle paralysis. This helps to keep the skin youthful, structure and function, however, side effects may occur or addiction develops over time if such procedures are abused.

Vascular system of the skin

Not only the structure of the skin itself is complex, but also the system of blood vessels that are responsible for nourishing the dermis and some layers of the epidermis with oxygen and useful substances. The action of various cosmetics is aimed at activating blood circulation. They are used to tone and strengthen the capillaries that form a complex network under the skin. With the help of massage, you can also improve the movement of blood through small vessels.

The speed of blood circulation in the cells that make up the skin affects the regeneration processes. Some scientists argue that the cells of the epidermis and dermis are able to retain toxic substances, preventing their penetration into the bloodstream, with which they are carried throughout the body.

Passive and active functions of the skin

Another important question: what is the significance of the skin? There is a definition that this is the most extensive and largest vital organ that provides reliable protection to the entire body. The thickness of the skin is different - from 0.5 to 5 mm.

The functions of the epidermis, middle layer and fiber differ. They can be divided into basic and additional, active and passive. The skin protects the body from exposure to cold and heat, mechanical damage, chemicals, pathogenic microorganisms. These functions can be classified as passive.

Active functions of the skin:

• fights pathogenic microbes inside the dermis, hypodermis, lower layers of the epidermis;
• maintains a normal temperature due to the release of sweat and the receipt of certain signals from the brain through the nerve endings;
• receives signals from the external environment (touch, pain);
• some cells of the dermis and epidermis are able to recognize allergens and respond accordingly to their action;
• takes part in the production of vitamin D;
• due to melanocytes, it produces melanin - a coloring pigment;
• regulates water and mineral metabolism.

Leather I Skin (cutis)

The skin is involved in the processes of immunity. Distinguish nonspecific, not dependent on previous infections or vaccinations, formed when the skin is exposed to UV radiation, and specific, which develops when penetration into K. agents to which it is especially sensitive, for example, the causative agent of anthrax. The skin has a low electrical conductivity, and its electrical resistance, especially the stratum corneum, is high. Electroresistance decreases in moist areas of K., especially with increased sweating, as well as in individuals with a predominance of the tone of the parasympathetic nervous system. Electrical resistance depends on the physical properties of K., the functional state of the sebaceous and sweat glands, K.'s blood vessels, and the nervous and endocrine systems.

Through the skin (excluding K. of the head) per day allocates 7-9 G carbon dioxide and absorbs t° 30° 3-4 G oxygen, which is about 2% of the total gas exchange in the body. Cutaneous respiration intensifies with an increase in ambient temperature, during physical work, an increase in barometric pressure, during digestion, acute inflammatory processes in the skin, etc. Skin respiration is closely related to redox processes, the activity of sweat glands rich in blood vessels and nerve fibers.

The absorption function is complex and not well understood. through K. water and dissolved salts in mammals practically does not occur due to the presence of lipid-impregnated shiny and horny layers that perform. Fat-soluble substances are absorbed directly through the epidermis, and water-soluble substances are absorbed through the hair follicles and through the excretory ducts of the sweat glands during the period of inhibition of sweating. Gaseous (for example, carbon dioxide) and some substances that dissolve and dissolve in them (chloroform, ether, etc.) are easily absorbed. Most toxic gases, except for skin blistering such as mustard gas, lewisite, do not penetrate through K.. Morphine, ethylene glycol monoethyl ether, dimethyl sulfoxide and other substances are easily absorbed, in a small amount -.

Excretory function K. is carried out by sweat and sebaceous glands. The amount of substances secreted through K. depends on gender, age, topographic features of the skin (see Sweat glands , Sebaceous glands) . With insufficiency of kidney or liver function through K., such substances that are usually excreted in the urine (, bile pigments, etc.) increase. occurs synchronously in different parts of K. under the control of c.n.s. The composition of sweat includes organic substances (0.6%), chloride (0.5%), impurities of urea, choline, and volatile fatty acids. On average, from 700 to 1300 are allocated per day ml sweat. sweat depends on the ambient temperature, K.'s condition, the intensity of the basal metabolism, etc. Sweating increases with an increase in ambient temperature, dry air, K.'s hyperemia; during sleep or anesthesia, it sharply decreases and even stops. sebaceous glands consists of 2/3 of water, and 1/3 of analogues of casein, cholesterol and some salts. With it, free fatty and unsaponifiable acids, metabolic products of sex hormones, etc. are released. The maximum sebaceous glands are observed from puberty to 20-25 years. The skin plays the role of a filter that prevents excess water from being released to the surface.

Pigment-forming function To. consists in development of melanin. This is produced by melanocytes, which contain specific cytoplasmic organelles - melanosomes, on the protein matrix of which melanin is synthesized from tyrosine under the action of tyrosinase. It is deposited as a melanoprotein complex. Melanogenesis is regulated by the melanocyte-stimulating hormone of the pituitary gland. skin is mainly due to the deposition of melanin. However, human K. contains other pigments - melanoid, oxyhemoglobin and reduced. Violation of pigment formation leads to hyperpigmentation (for example, with Addison's disease) or depigmentation (etc.).

Among the nerve fibers innervating blood vessels K., adrenergic and cholinergic are distinguished. Neurohumoral factors constantly exert a regulatory influence on the blood vessels. , norepinephrine and the posterior pituitary gland cause vasoconstriction, and acetylcholine, and androgens dilate them. Normally, most of K.'s blood vessels are in a semi-contracted state, the rate of blood flow in the capillaries is negligible; it varies greatly depending on local and general causes. The dilated blood vessels of the dermis can accommodate up to 1 l blood (depositing role of the skin); their rapid expansion can lead to significant circulatory disorders.

K. plays a very important role in thermoregulation of the organism. The production of thermal energy in the body due to thermoregulation is maintained at a certain level despite fluctuations in ambient temperature (see Thermoregulation) . 80% occurs through K. by radiation, heat conduction, and due to the evaporation of sweat. The fatty lubrication of the surface K. and the poor thermal conductivity of the subcutaneous tissue prevent both excess heat or cold from the outside, and excessive heat loss.

Thermoregulation is a complex reflex act in which the brain (thermoregulation centers) and sympathetic are involved; it is also influenced by the vasomotor and respiratory centers, sweating, adrenal glands, pituitary gland, thyroid and gonads. K.'s temperature depends on the time of day, food intake, the intensity of perspiration and sebum secretion, muscle work, and the person's age. During the day, a person allocates about 2600 calories of heat, children are slightly more. K.'s temperature in its different parts is not the same (from 31.1 to 36.2 °), the highest temperature in the skin folds is up to 37 ° in the norm.

The skin plays an important role in metabolic processes. In addition to gas exchange, which is carried out during skin respiration, interstitial carbohydrate, protein, fat, salt, and vitamin metabolism occurs in K.. In terms of the intensity of water, mineral, and carbon dioxide metabolism, K. is slightly inferior to the liver and muscles. K. faster and easier than other organs, accumulates and gives a large amount of water. Through K. water is allocated twice as much as through the lungs. The processes of metabolism and acid-base balance depend on many factors, including human nutrition (for example, with the abuse of sour food in K., the sodium content decreases). K., especially subcutaneous tissue, is a powerful depot of nutrients that are consumed by the body during the period of starvation.

The skin is a huge receptor field through which the body communicates with the environment. It participates in various reflex reactions - to cold, heat, etc., as well as in plantar, pilomotor and other reflexes. Exteroceptors K. perceive various external stimuli, which are transmitted in the form of a nerve impulse to the central nervous system. There are different types of skin sensitivity. Pain occurs when exposed to mechanical, thermal stimuli and electric current, temperature - cold and thermal stimuli. Tactile sensitivity (see Touch) is most pronounced on the fingertips, in the K. of the external genitalia, in the nipple area, where there is the largest number of highly differentiated nerve endings. Its variant, obviously, is hairy sensitivity K., which occurs when touching the hair and depends on irritation of the complex basket-shaped nerve plexus of the hair follicle. Complex types of sensitivity include a sense of place (localization), stereognostic, two-dimensional-spatial and a sense of separateness (discriminatory sensitivity).

Different parts of K. do not perceive the same thing in the same way. They think that 1 cm 2 skin is 100-200 pain points, 12-15 cold, 1-2 heat and about 25 pressure points. Most skin receptors are polyvalent in function. Under the influence of various environmental factors, the number of functioning sensitive receptors may change, develops, especially to tactile and temperature stimuli. to painful stimuli is the weakest.

Unconditional and conditional skin play an important role in the life of the organism. Newborns have congenital unconditioned skin reflexes - sucking and grasping. There are skin-skin reflexes (irritation and response occurs to K.), musculo-hairy, vasomotor unconditioned - reflex Dermographism , vasomotor reactions in response to intradermal administration of adrenaline, histamine, etc. The musculoskeletal reactions include abdominal, cremaster reflex, plantar. There are also galvanic skin reflex, reflex to. Impulses coming from skin receptors maintain normal muscles. Musculoskeletal reflexes are of great importance in human labor activity, especially in the automation of movements, the accuracy of which is developed as a result of differentiation of skin and visual sensations, combined with proprioceptive ones coming from muscles and tendons. Painful irritations To. are accompanied by a change in the secretion of the pituitary gland, increased release of adrenaline, inhibition of the digestive process, and a change in the biocurrents of the brain. There are also skin-respiratory, skin-vascular and other skin-visceral reflexes. Well-known reflex, which occurs not only at the sight of blood-sucking insects, but even at the mere mention of them, conditioned reflex (the so-called erythema of shame, anger), "goosebumps". The same conditioned reflex mechanism underlies the hemorrhages, blisters, and even blisters caused by suggestion.

Structural proteins have been identified in the skin: , reticulin, and keratin. concentrated mainly in the dermis, it makes up about 70% of water- and oil-deprived skin (see collagens) . Reticulin and elastin are contained in K. in much smaller quantities, they form the basis of the reticulin and elastic fibers of the dermis, the connective tissue membranes of the sebaceous and sweat glands, and are part of the membrane of the hair follicles. Keratin is the basis of the stratum corneum K. It ends in its cells (the process of formation of horny substance in the epidermis), which begins in the basal epidermocytes. The skin also contains protein breakdown products: uric acid, and creatinine, ammonia, etc. There are three times more of them in the skin (up to 150 mg%) than in the blood; especially many of them accumulate in pathologically altered areas of K. with the predominance of decay processes. The process of formation of the horny substance is regulated by genetic mechanisms, as well as by the endocrine and immune systems. Violations of keratinization () are observed in skin tumors, Darier's disease, etc. A significant part of the cells of K., like other cells of the body (especially their nuclei), are nucleoproteins and (and RNA).

Of the carbohydrates in K., glycogen and glycosaminoglycans are contained. With the depolymerization of glycosaminoglycans (for example, with an increase in the activity of hyaluronidase), the gels formed by them decrease, and thus. K. increases for microorganisms and various toxic products, in K. it is formed and accumulates in mast cells; it plays an important role in the regulation of microcirculatory processes.

The skin and its surface contain a variety of lipids. Neutral make up the bulk of the subcutaneous tissue. They are dominated by the most fusible triglyceride - triolein (up to 70%), and therefore human has the lowest melting point (15 °). On the surface of K., lipids mix and form.

The water content in K. ranges from 62 to 71%. The skin is rich in enzymes, the most important of which are phosphorylase,. From 0.7 to 1% of its dry weight falls on the mineral components of K., and in the subcutaneous tissue - about 0.5%. The skin is an important depot of sodium, potassium, calcium and other trace elements. For the normal state of K., zinc, arsenic, and some others that are part of enzymes, vitamins or play the role of activators of biological processes are most important.

The skin is involved in the body's metabolism; it deposits blood, lymph, tissue metabolism products, macro- and microelements; due to the fact that proteins are temporarily retained in K., their toxic effect on other organs is weakened. K. frees the body from excess water, toxic metabolites, which improves the processes of thermoregulation, increases the barrier, bactericidal and other functions. Separate stages of the chemical transformation of a number of substances involved in metabolic processes occurring in other organs and tissues of the body take place in the skin. It produces sebum and.

Violation of protein metabolism leads to the development of gout (Gout) , Amyloidosis , Porfiria , skin mucinosis (deposition of mucin in K.) and other diseases with pronounced changes in K. Violation of lipid metabolism is the cause of lipidosis (Lipidoses) . Changes in carbohydrate metabolism, accompanied by accumulation in the blood and K., lead to lipoid necrobiosis (Necrobiosis lipoidis) , contribute to the occurrence of furunculosis (see Furuncle , chronic Pyoderma and other diseases K. Abnormalities and activity of enzymes are noted in dermatoses, such as eczema (Eczema) , Neurodermatitis , Psoriasis .

The metabolism in K. is influenced by nervous and hormonal factors. In the occurrence of skin diseases, dysregulation of biochemical processes at the cellular and intracellular levels plays an important role. In particular, an important pathogenetic mechanism of psoriasis is a violation of the cellular regulatory system adenylcyclase - cyclic.

Vitamin A deficiency plays a role in the development of Ichthyosis a , seborrhea (Seborrhea) , Deverage disease (Deverage disease) , nail dystrophy (see Nails), etc. A lack of vitamin PP causes the development of pellagra (Pellagra) with severe skin lesions, and vitamin C - scurvy (scurvy) . The pathogenesis of neurodermatitis is associated with a lack of B vitamins, especially B 6 . In the pathogenesis of some skin diseases, disturbances in water and mineral metabolism are important. Shifts in acid-base balance affect the bactericidal functions of the skin. In adults, the pH of the skin surface is 3.8-5.6: in women, this figure is somewhat higher than in men. In the armpits, inguinal-femoral folds, sweat has a slightly alkaline or slightly acidic reaction (pH 6.1-7.2). Pronounced pH shifts towards an alkaline reaction contribute to the occurrence of mycoses (Mycoses) . In addition to the biochemical processes common to the body, transformations inherent only to it occur in K.: the formation of keratin, melanin, sebum, and sweat.

With slowly developing acidosis, intercellular edema occurs (), manifested by multi-chamber vesicles (see Rashes) . In case of violation of intercellular connections, single-chamber intraepidermal bubbles are formed. Coagulative and collicative cell death (see Necrosis) leads to an erosion that heals without scarring or an ulcer (Ulcer) , penetrating into the connective tissue part of K. and healing with the formation of a scar.

Often inflammation To. is accompanied by the development of purulent exudate and the formation of pustules (see Rash) . With productive inflammation, a cellular one is formed with a dermal papule or tubercle (with specific inflammation). , resolving without necrosis, ends with cicatricial atrophy, and decaying - with a scar. A special group of inflammatory processes are chronic granulomas. Inflammatory infiltrate in the dermis, violating, causes the appearance of various secondary changes in the epidermis (edema, atrophy, etc.). Inflammation of the subcutaneous tissue is manifested by edema, the formation of a node or diffuse infiltrate. Inflammation To. can occur as a result of hypersensitivity to a strictly defined antigen (see Allergy) , in other cases it is not specific and is caused by any strong stimulus.

K.'s condition is connected with a condition of all organism. Nephropathy is often accompanied by the so-called cutaneous uremia due to azotemia, oxalemia, urea retention. Foci of chronic infection (in the tonsils, teeth, etc.) can be the cause of a number of dermatoses. Often a background for the onset and development of eczema, urticaria (urticaria) , neurodermatitis, circular hair loss are neurovegetative disorders. After mental trauma, red flat, psoriasis, etc. often appear. The skin reacts to disruption of the endocrine system. So, a disorder of the thyroid gland contributes to the development of skin myxedema, excessive sweating, itching, urticaria, eczema, etc.; ovarian dysfunction - chloasma (see Skin dyschromia) ; disease of the adrenal glands - hirsutism (see Virile syndrome) , increased pigmentation; diseases of the pancreas are accompanied by persistent furunculosis, etc.

Some (for example,), atmospheric factors (long-term, wind, cold, etc.), mechanical, physical, and chemical influences can have an adverse effect on K. Stagnation in the circulatory system contributes to the occurrence of varicose ulcers, etc.

The variety of factors affecting K., the complexity of its morphological structure, and the wide range of functions performed cause a large number of skin diseases (about 2 thousand different forms), the classification of which has not been finally developed (see Dermatosis) .

A large group is made up of K.'s lesions associated with hereditary factors (see Genodermatosis) or which are congenital malformations of the fetus as a result of adverse effects in the processes of embryogenesis (intrauterine infection intoxication, circulatory disorders, etc.). K., due to genetic factors, are very diverse ; often they wear family. Congenital deformities and anomalies in the development of the body that are not associated with genetic factors are more rare. Part of the malformations of K. are abortive manifestations of more complex birth defects: swimming membranes - an abortive form of syndactyly (see Hand) , hypertrichosis of the sacrum - a manifestation of hidden, congenital sinuses and cysts on the neck and face - the result of incomplete closure of congenital fissures, additional pectoral nipples - incomplete gynecomastia, etc.

With other congenital anomalies K., the main disturbances in the development of the fetus are concentrated in K. So, congenital absence is known - K., accompanied by underdevelopment of the appendages K. and teeth (congenital ectodermal). Congenital aplasia of the skin (defect of the epidermis and dermis) is characterized by the presence of ulcers in a child at birth up to 10 cm in the parietal, occipital or posterior auricular region of the head. A congenital defect K. is formed in the fetus in the form of a bullous lesion (bubble), by the time the child is born, a bubble is formed at the site. Gradually, it closes, leaving behind cicatricial atrophy. Congenital aplasia To. can be combined with a defect in the bones of the skull. At other types of an aplasia To. the sites deprived of skin can be located on a trunk, extremities. They are covered with a thin membrane through which the underlying organs and tissues are clearly visible.

Such congenital anomalies as rubber hyperelastic K., imperfect desmogenesis, pachydermia, are associated with changes in the connective tissue. Malformations include birthmarks of various clinical forms, angiomas, and lymphangiomas.

A large group is made up of diseases caused by damage to K. - mechanical (for example, attrition, callosity , Intertrigo) , radiation, incl. ionizing radiation (see Dermatitis , Photodermatoses) , exposure to electric current, high and low temperatures (see Burns , frostbite) , as well as various chemical and biological factors.

Allergic reactions of the body, changes in the nervous and endocrine systems (see Toxidermia , Hives , Eczema , Neurodermatitis , Scabies, etc.). The skin is often affected in diffuse connective tissue disorders (Diffuse connective tissue disorders) , Sarcoidosis , skin vasculitis (skin vasculitis) , violations of metabolic processes in the body (see Lipidoses , Amyloidosis , Calcinosis , xanthomatosis, etc.).

Pathological processes in K., associated mainly with individual morphological structures of the skin, see Hair , Nails , sweat glands , Sebaceous glands .

skin tumors. According to the WHO histological classification (1980), among tumors K. distinguish skin, benign, premalignant (precancerous) skin diseases, tumors with locally destructive growth and malignant tumors. Epithelial, pigment and connective tissue tumors of the skin are distinguished by origin.

Skin malformations. These include papillomatous, comedonal nevus, epidermal cyst, hairy cyst, dermoid cyst (see Dermoid) , whiteheads, atheroma, etc.

Papillomatous malformation is characterized by the appearance of warty papillomatous growths (hyperkeratotic nevus) on any site of K. from the moment of birth or in early childhood. There is a limited form in the form of a dense grayish-brown focus and a multiple form, in which the lesions may tend to be ordered localization (according to the Zakharyin-Ged zones). often combined with other malformations of the skin (pigmented nevus, nevus of the sebaceous glands).

Comedonal nevus is localized mainly on the limbs and trunk. It is within which follicular papules are closely grouped. The central part of the papules is permeated with dark gray or black horny masses (remains after their removal).

Seborrheic keratosis, or seborrheic, occurs more often in the elderly (after 40 years); localized on closed areas of the skin, such as the trunk ( rice. 3 ). It is characterized by the appearance of sharply hyperpigmented (from brown to black) plaques, often multiple with a diameter of 0.5-4 cm and more, covered with easily removable greasy crusts.

Benign epithelial tumors may originate from sweat glands, hair follicles, and sebaceous glands. Benign tumors of the sweat glands are papillary, eccrine poroma, papillary, eccrine spiradenoma, etc.

Papillary hidradenoma is a solitary mobile tumor of the apocrine gland. It occurs mainly in women, localized in the K. of the external genitalia, as well as in the perineum. It has a soft texture and large sizes (4-6 cm). It usually grows slowly.

Eccrine poroma - a tumor of the intradermal part of the duct of the eccrine sweat gland. It is localized mainly on the plantar surface of the feet, on the palms, the inner surface of the fingers. It is a single flattened tumor formation in the form of a plaque with a diameter of 10-20 mm with a smooth or hyperkeratotic surface of pink or dark brown color. Eccrine poroma is painless on palpation; may ulcerate.

Papillary syringocystadenoma () - excretory duct of the sweat gland. It is usually a nevoid formation. It is rare, usually in children and adolescents. It is located more often on the scalp, neck, inguinal and axillary folds. It has the appearance of a single or multiple tumor-like formations of a dense consistency, grayish or grayish-yellow in color with papillomatous growths on the surface.

Eccrine spiradenoma is a tumor that develops from the glomerular part of the sweat glands. Rare, more common in young men. It is localized, as a rule, on To. of the person, a forward surface of a trunk. It is a dark yellow or bluish-red color, dense consistency, sometimes painful on palpation.

Benign epithelial tumors of the hair follicle include cylindric, trichoepithelioma, etc. localized on the face and scalp (the so-called turban tumor). It is a large tumor with a smooth surface ( rice. 4 ), characterized by progressive growth, a tendency to recurrence after surgical excision.

Trichoepithelioma is multiple and single. The plural form is more common in childhood - hereditary. Numerous small nodules are located mainly on the face ( rice. five ), sometimes the scalp, neck, front surface of the body. A single form occurs mainly in adults - the actual trichoepithelioma. Localized on any part of the body, usually on the face.

A benign tumor is a true adenoma of the sebaceous glands. It occurs very rarely, mainly in old age. It has the form of single, dense, round, sometimes sitting on the leg nodules or knots.

Fibroma can appear on any part of K. Distinguish between hard and soft fibroma. A solid fibroma has a broad base, firm texture, smooth surface, normal skin color or slightly pink. This is a limitedly mobile tumor, rising above the surface of K. Soft fibroma is multiple and single. It is localized mainly on the neck, the anterior surface of the chest, in the inguinal folds and armpits. It has the appearance of a bag-shaped hanging tumor of various sizes with a wrinkled surface of pinkish or brown color.

Dermatofibroma can be solitary ( rice. 6 ) and multiple. It occurs, as a rule, in women, on K. of the upper and lower extremities. of a dense consistence, dark brown color, rounded shape is deeply located in K. more often does not protrude above its surface.

Dermatofibrosarcoma bulging is a locally invasive tumor. It occurs more often in men in the shoulder girdle, on the head. It happens single and multiple. protrudes above the surface To., has a smooth tuberous surface, which can ulcerate. Slow and a tendency to develop relapses after excision are characteristic.

Hemangioma develops from blood vessels. Isolate the capillary rice. 7 ), arterial, arteriovenous and cavernous ( rice. 8 ) forms (see Blood vessels , tumors). A special form of hemangioma is pyogenic granuloma ( rice. nine ). Arises as a result, localized on the face, more often in the lips, on the upper limbs. It is a tumor of dark red color on a stalk or a wide base with an erosive surface.

Lymphangioma is a tumor arising from the lymphatic vessels. It often appears from birth. Localized on any part of the skin. Associated with hemangioma. There are capillary, cystic and cavernous forms. Against the background of cystic and cavernous lymphangiomas, areas of papillomatosis and hyperkeratosis may develop. Secondary lymphangioma may be a manifestation of lymphostasis, sometimes appears after an infectious disease (for example, erysipelas).

Leiomyoma is a tumor that arises from the muscles that raise the hair. There are 3 clinical varieties: multiple leiomyoma, solitary leiomyoma on the genitals and nipples, and angioleiomyoma developing from small blood vessels K. Multiple leiomyoma is characterized by the appearance of small tumors on the trunk and extremities (3-5 mm in diameter) rounded, with a smooth surface, painful on palpation, tending to group. Solitary leiomyoma has a size of up to 20 mm in diameter; erythema is observed around the lesion. - solitary tumor of saturated red color, dense elastic consistency. It is localized often in the area of ​​large joints.

Lipoma - tumor of adipose tissue in the form of single or multiple foci. Are localized on any site To., towering above its surface. It is usually large (up to 10 cm in diameter), pasty consistency, normal skin color. A variant of the lipoma is symmetrical multiple (Derkuma), characterized by the appearance mainly on the upper limbs of lesions that are painful on palpation.

Benign pigmented tumors K. include various forms of pigmented nevus and. Pigmented nevi are characterized by the appearance on K. of spots or neoplasms consisting of nevus cells. They occur after birth or in the first years of life; sometimes appear in adolescence and middle age under the influence of sunlight or during pregnancy. Pigmented nevi - spots or flat nodules of dark gray, brown or black color, elongated or rounded shape, 1 cm and more ( rice. 10 ). The surface of the pigmented nevus is often smooth, but sometimes there are papillary warty growths. In some cases, a large nevus occupies a significant part of the K. of the trunk, face, neck, or limbs and is a cosmetic defect (giant pigmented nevus). Hair often grows on its surface. Sometimes the nevus has a blue color - a blue nevus. It is more common in women on the skin of the face and forearms. A variety of blue nevus is Mongolian. It occurs predominantly in Asians 1-2 days after birth, usually in the lumbosacral region. Has a bluish or brownish color, diameter up to 10 cm and more. After 4-5 years, the spot gradually fades and disappears.

Nevus of Ota is more often observed in women - representatives of Asian peoples. It is congenital or appears in the first years of life. It has the appearance of a pigment spot located on the face along the I and II branches of the trigeminal nerve (, zygomatic region, wings of the nose, as well as sclera and eyes). Sutton's nevus (Sutton's disease) is also distinguished - a small pigment spot with a rim of depigmented skin, localized on the trunk or limbs.

Blue nevus, nevus of Ota, pigmented nevus with papillary warty growths can transform into melanoma when traumatized.

Premalignant skin diseases. These include xeroderma pigmentosa (Xeroderma pigmentosa) , radiation damage to the skin (see radiation damage) , solar keratosis, etc. A number of authors also include in this group Bowen's disease, Keir's disease and Paget's disease (with localization outside the nipple and areola of the breast), which are rare.

Solar keratosis occurs as a result of excessive sun exposure. At the same time, against the background of poikiloderma (a combination of foci of hyperpigmentation with areas of atrophy), multiple foci of hyperkeratosis appear in the form of elongated or oval plaques up to 0.5-1 cm in diameter, covered with dense gray flakes. The affected areas may develop Bowen's disease or squamous cell carcinoma.

Bowen's disease is considered by most researchers as intraepidermal cancer. It is observed mainly in middle-aged and elderly people, more often localized on the K. of the face, torso. Usually it is a single grayish-brown plaque, slightly infiltrated, with irregular, clear boundaries, covered with scales or crusts.

The lesion slowly grows along the periphery, its surface often ulcerates, it has areas of atrophy, which, together with scales and cortical layers, gives the tumor a mottled appearance. In persons suffering from Bowen's disease, cancer of the internal organs is often detected.

Paget's disease, when localized outside the nipple and areas of the mammary gland, is characterized by limited foci of maceration and weeping, located mainly in the perineum and navel.

Tumors with locally destructive growth. An epithelial tumor with locally destructive growth is (basal cell carcinoma). It develops from the basal layer of the epidermis or appendages K. (sebaceous and sweat glands). This is the most common epithelial tumor K. It is observed mainly in old age. Characterized by invasive growth; rarely metastasizes. Clinical manifestations are varied. There are superficial (the most favorable form), cystic, ulcerative, scleroderma-like and pigmented forms of basalioma.

Superficial basalioma - a limited spot, along the periphery of which there is a roller, consisting of individual nodules ("pearls"). It is localized more often in open areas of the body that are exposed to insolation, prolonged mechanical irritation. In fair-skinned individuals, multiple lesions may develop that coalesce into large, scaly plaques ( rice. 12 ). Often, in the center of the plaque, spontaneous growth occurs, and along the periphery, tumor growth (self-scarring basalioma).

With cystic basal cell carcinoma, the lesion is more often solitary, sharply delimited from the surrounding tissue, bright pink in color, doughy in consistency; on the surface there are often telangiectasias. It is localized mainly on the skin of the face (around the eyes, nose).

Ulcerative basalioma ( rice. 13. 14 ) may develop from superficial or cystic. It occurs more often on the chin, at the base of the nose or the inner corner of the eye. It is manifested by the formation of nodules prone to ulceration. It is characterized by tumor infiltration of the underlying tissues with the development of a defect up to the destruction of bone and cartilage tissue. The most severe forms of ulcerative basalioma are - corrosive ulcer ( rice. 15 ) and ulcus terebrans (penetrating ulcer). With ulcus terebrans, the process also spreads to the periphery. In some cases, papillomatous growths (verrucous-ulcerative basalioma) appear on the ulcerated surface.

With scleroderma-like basalioma on the face, upper body, plaques of a dense consistency with clear boundaries are formed. They resemble foci of scleroderma, in which there is an erythematous corolla along the periphery of the focus. In contrast to scleroderma, in scleroderma-like basalioma, a roller-shaped edge and single nodules - “pearls” are found along the periphery of the lesion.

Pigmented basalioma has a darker color (from yellowish brown or bluish brown to dark brown or black), which is associated with the presence of melanin in the cytoplasm of tumor cells.

Depending on the histological picture, multicentric, solid and adenoid forms of basalioma are distinguished. As a rule, there is no regular connection between the histological picture and the clinical form of basalioma. In cases where structures resembling are histologically revealed, they speak of trichobasalioma. It is localized on K. forehead, scalp in the form of a single, less often multiple nodules of a rounded shape from 2 to 5 mm in diameter, dense texture, dark gray or brownish color. In rare cases, the nodules are larger, have an uneven surface, sometimes with pronounced telangiectasias.

For malignant tumors of the skin include squamous cell carcinoma, pigmented tumors - precancerous Dubrey and melanoma (Melanoma) . Squamous cell carcinoma K. is an epithelial malignant tumor. Occurs more often in places of constant irritation, mechanical, against the background of long-term non-healing trophic ulcers, fistulas, radiation damage to K., and can also develop from lesions characteristic of Bowen's disease, xeroderma pigmentosa, and solar keratosis. According to the clinical picture, endophytic (ulcerative) and exophytic (tumor or papillary) forms of squamous cell carcinoma are distinguished. In the ulcerative form, a crater-shaped ulcer with a dense bottom and ridge-like edges is formed. slowly but steadily growing, bleeding. In the papillary form, solitary hard nodules look like a wart or keratoacanthoma, merge with each other into large lesions resembling cauliflower ( rice. 16 ). Squamous cell keratinizing cancer is characterized by infiltrative growth in the underlying tissues, gives metastases to the lymph nodes and lymphatic vessels, and in advanced cases - to the blood vessels.

Dubreu's precancerous melanosis is a slow-growing tumor that usually occurs after age 30 and is more common in women. It is localized, as a rule, in open areas of K. It has the appearance of a single plaque of large sizes (40-60 mm in diameter) with uneven outlines and uneven pigmentation (from light brown to dark brown and black). A growth trend, a change in the color of the tumor (darkens), the development of papillomatous growths on the surface, or the appearance of areas of atrophy indicate its transformation into melanoma.

Treatment. The majority of tumors To. is not followed by noticeable subjective sensations. When neoplasms appear, K. the patient should be referred for a consultation with an oncologist or dermatologist (oncologist), who establishes and conducts on the basis of anamnesis data, clinical signs and results of histological and cytological studies. With benign tumors To. surgical treatment (removal of the tumor) is carried out in case of localization of the tumor in places exposed to injury, as well as at the request of the patient (for example, with a cosmetic defect). Premalignant diseases are subject to mandatory treatment. For this purpose, surgical is used, incl. electrosurgical, cryodestruction, radiation therapy (Radiation therapy) , laser (see Lasers) . According to indications, various cytostatic drugs (5-fluorouracil, ftorafur, prospidin, etc.) are also locally prescribed.

Prevention consists in the early detection of the initial signs of a tumor K., conducting preventive examinations and identifying risk groups (persons suffering from long-term non-healing ulcers, with cicatricial changes in the skin, etc.), in the active treatment of precancerous dermatoses. Excessive insolation and contact with oncogenic substances should be avoided.

Bibliography: Apatenko A.K. Epithelial tumors and malformations of the skin, M., 1973; Berenbein B.A. Skin pseudocancer, M., 1980; Differential Skin Diseases, ed. B.A. Berenbein and A.A. Studnitsina, p. 366, M., 1989; Kalantaevskaya K.A. and physiology of the human skin. Kyiv, 1972; Kozhevnikov P.V. General, L., 1970; Guidelines for the pathoanatomical diagnosis of human tumors, ed. ON THE. Kraevsky and A.V. Smolyannikova, p. 403, M, 1976, bibliogr.; Trapeznikov N.N. etc. Pigmented nevi and neoplasms of the skin, M., 1976, bibliogr.

Rice. 1. The structure of the skin of a human finger: 1-5 - epidermis (1 - basal layer, 2 - prickly layer, 3 - granular layer, 4 - shiny layer, 5 - stratum corneum); 6 - excretory duct of the sweat gland; 7-8 - dermis (7 - papillary layer, 8 - reticular layer); 9 - terminal sweat gland; 10 - hypodermis.

A node in the lower part of the auricle "> of the patient can help to weaken the course of the developing lesion of K. or even be suspended. By taking a number of precautions, you can prevent the spread of a number of infectious skin diseases even before going to the doctor.

In infants, exudative-catarrhal occurs, manifested in the hereditary tendency of the child's body to inflammatory processes, allergic reactions. The first signs of such diathesis may be in the nature of a milky scab, persistent diaper rash of the skin, the so-called geographical tongue.

milk scab manifests itself in the form of yellowish scale-crusts, rather tightly seated on the skin of the scalp of the child, especially in the parietal region. In these cases, the nursing mother should carefully analyze her diet and exclude foods that have an allergenic effect from it (see below). Warm boiled vegetable oil (sunflower, olive, peach) should be applied to the crusts for several hours, then carefully comb the softened crusts with a comb and then wash your hair; if necessary, repeat the procedure.

With excessively tight swaddling of a child, overheating, insufficiently thorough skin care (especially in the area of ​​\u200b\u200bthe axillary, inguinal-femoral, intergluteal folds), as a result of the irritating effect of skin secretion products (fat, sweat), as well as urine, feces, the skin turns red, macerated - diaper rash occurs. To prevent further development of this process, it is necessary to make adjustments to the child care system, make sure that he does not overheat, change linen frequently, boil, iron him. An important role is played by careful observance of the toilet of the genitals and perineum: after each urination and defecation, the skin should be washed with a slightly pink solution of potassium permanganate or a decoction of chamomile, oak bark, St. John's wort or string, diluted in boiled water to a slightly yellow color. Skin folds should be treated with sterile oil (olive, peach, sunflower, rosehip, sea buckthorn), fish oil, calcium liniment or baby cream. You can also use talcum powder. It is advisable to leave the affected areas of the body open more often. Persistent diaper rash may be a sign of exudative diathesis, and therefore should be reviewed by a nursing mother (see below). In the presence of erosions and abrasions in the area of ​​diaper rash, it easily joins, in this case the child should be shown to the doctor.

In conditions of improper child care (excessive, insufficient fluid administration), in children who are debilitated, suffering from rickets, febrile, as a result of imperfection of the thermoregulation system and increased sweating, small (dotted) pink nodules and vesicles often appear on the skin of the back, back of the neck, buttocks - prickly heat. In this case, daily hygiene with the addition of chamomile decoction is advisable. After washing, the skin is gently blotted with soft, carefully ironed diapers or a towel. The child's skin should be wiped daily with a warm alcohol solution (half vodka with boiled water). You should also give the child plenty to drink, take care of his more comfortable clothes, stop excessive wrappings, use air baths, avoid using oilcloth or plastic film in the form of liners under the sheet during a long sleep, which will help to avoid overheating and sweating.

Since children's skin is delicate, the slightest injury and pollution can lead to the appearance of pustules- small red nodules with a purulent head on top or vesicles with yellowish purulent contents. When such skin changes appear, you should refrain from bathing the child, treat if they are single, with a solution of brilliant green (brilliant green), fucorcin or gentian violet, and wipe the skin around them with a warm alcohol solution (half vodka with boiled water). In this case, the frequent change of linen, which must be boiled and thoroughly ironed, is very important. If there are many rashes or they continue to appear, you should consult a dermatologist or pediatrician.

Manifestations of allergies on the skin. If the diet of a nursing mother is violated (the use of oranges, chocolate, honey, condensed milk, etc.), with the introduction of complementary foods or the transition to artificial feeding in infants, manifestations of exudative diathesis may occur in the form of reddening of the skin, bright red small nodules, vesicles, with opening of which weeping areas of the skin are formed. After a while, they become covered with yellowish scales, crusts. More often, such skin changes occur on the face (especially on the cheeks), buttocks, back surface of the hands, forearms, feet, legs, thighs and are accompanied by itching. These skin changes can progress to childhood eczema and other difficult-to-treat allergic skin conditions. Combing the affected skin, the child will be able to introduce pathogens into the lesions, as a result of which the process will worsen. The development of exudative diathesis is promoted by age-related immaturity of the digestive apparatus, insufficient secretory activity, and sometimes enzyme deficiency, as a result of which a number of foods can cause an allergic reaction in such children in the form of skin lesions. It should be borne in mind that the leading food allergens for children can most often be cow's milk, especially its protein lactoglobulin (boiling milk causes the destruction of lactoglobulin, and milk becomes less allergenic); chicken eggs, especially protein (heat treatment reduces their allergic properties, but does not completely destroy); fish, caviar, crayfish, crabs, shrimp and products from them (heat treatment has little effect on the degree of allergic reaction to these products); grain products (usually wheat, rye,); fruits and (most often oranges, tangerines, lemons, strawberries, strawberries, tomatoes, carrots); and nuts; honey, chocolate, coffee, cocoa.

The spread of artificial feeding, the early introduction of mixtures prepared from cow's milk, often leads to a rapid increase in sensitivity to food allergens. At the same time, it can be combined with medicinal, household (homemade, fluff, animal hair), pollen (pollen of grasses, flowering trees). If a child is expressed to milk, then you can try to use it in his diet (kefir, matsoni, biolact, etc.). Also suitable are acidophilic products prepared by fermenting dairy products, including dry ones, with special acidophilic lactobacilli that have proteolytic (protein-destroying) and antibacterial properties. You can introduce fruit, vegetable purees and beef meat at an earlier date, and cook cereals on fruit and vegetable broths. Products are often steamed to reduce the content of extractives.

G h potatoes, white cabbage, lettuce, peeled cucumbers, green onions, green apple puree, plums, dried fruits, rose hips, beef meat, cottage cheese. You can not give such children meat, chicken, fish broths, tomatoes, citrus fruits, cauliflower, green peas, spinach. In older children, you need to be very careful with the introduction of chicken, eggs, into the diet. With good tolerance, you can give boiled chicken meat (without skin and chicken broth), hard-boiled chicken eggs once a week.

Proper nutrition will in many cases prevent the development of chronic allergic diseases. At the same time, in the diet, it is necessary to provide for the intake of proteins, fats and carbohydrates, trace elements, vitamins, since this is a condition for the normal functioning of the body and, in particular, its immune system, which plays an important role in the development of allergic reactions.

Protein products are indispensable components of food, the deficiency of which in a child can lead to growth retardation, metabolic disorders, adverse changes in the function of the liver, pancreas, etc. The participation of proteins in the formation of the body's defense mechanisms (immunity) is very important. and vitamins contribute to the synthesis of hormones, enzymes. At the same time, easily absorbed, fats that enter the body in large quantities slow down the synthesis of protective antibodies, increase the tendency of tissues to inflammatory reactions, and enhance sensitization processes.

Among the foods that should be avoided by both children and adults with allergic skin rashes are eggs, canned food, citrus fruits, mushrooms, smoked and fatty sausages, crabs, strawberries, chocolate and honey.

Adults should adhere to a predominantly dairy-vegetarian diet with a reduced content of table salt, with the exception of spicy, smoked, salty foods, and alcohol. The diet may include boiled meat, fish, mostly river (non-fat), cottage cheese, kefir and other lactic acid products, buckwheat, rice and oatmeal, vegetarian soups, vegetables, fruits.