Skin and its functions. Interesting facts about human skin

The skin forms a common (outer) cover of the body, the area of ​​\u200b\u200bwhich in an adult is 1.5-2 m 2, and its thickness varies in different parts of the body from 0.5 to 4 mm, the weight of the entire skin is about 3 kg.

Skin functions

The skin protects the underlying tissues from mechanical damage, protects all internal organs from the effects of the external environment (pressure, friction, rupture, impact), and prevents the penetration of microbes and toxic substances into the body. The skin is constantly in contact with the external environment and has many functional inputs and outputs. Representing a huge receptor surface, the skin perceives the impact of various factors (pressure, humidity, temperature, etc.), provides pain and tactile sensitivity, and performs the function of thermoregulation.

Constantly in contact with the external environment, the skin releases metabolic products harmful to the body. Through the exits of the skin, water, salts and other residual products are removed. So, the skin is involved in metabolism, especially in water-salt metabolism. During the day, about 500 ml of water is excreted through the skin, which is 1% of its amount in the body. Various salts and products of protein metabolism are excreted through the sweat glands. The skin breathes by taking in oxygen and releasing carbon dioxide. In terms of the intensity of water, mineral and gas exchange, the skin is only slightly inferior to the liver and muscles.

The skin also performs many specific functions, the main of which are protective and signaling. The signal function of the skin is provided by numerous sensitive nerve endings - receptors located in all layers of the skin. With their help, we perceive pressure, cold, heat, pain, touch. In some areas of the skin, per 1 cm 2 of its surface, there are up to 200 painful, 12 cold, 2 thermal and 25 endings that respond to pressure. Skin sensitivity plays an important role in the interaction of the body with the external environment, it helps to avoid injuries, burns, frostbite.

Skin structure

The skin is made up of two layers:

• epidermis
• skin proper (dermis) with subcutaneous base

Between the epidermis and the skin itself lies the main membrane.

Epidermis forms the outermost layer of the skin. Its thickness varies from 0.07 to 0.4 mm; The epidermis reaches its greatest thickness in the area of ​​the sole (up to 1.5 mm). The epidermis consists of a stratified epithelium, the outer cells of which are keratinized and desquamated.

1. The germinal layer is the deepest, consisting of 5-15 rows of cells. Cells are born in this layer, which gradually replace the cells of the most superficial, keratinized layer of the epidermis.

   In the germ layer there is a pigment, its amount causes a different skin color. The pigment protects the human body from the penetration of ultraviolet rays. It is formed under the influence of sunlight, which is why the skin darkens when tanned. However, it should be remembered that under the influence of sunlight, the skin becomes rough, loses a lot of moisture, peels off, becomes covered with age spots and wrinkles. To avoid this, it is recommended to use sunscreens and lotions. It is necessary to follow the rules of exposure to the sun: it is necessary to sunbathe gradually, mainly in the morning. The maximum time spent in the sun should not exceed 1 hour. You can not sunbathe immediately after eating or on an empty stomach, it is extremely harmful to sleep in the sun. When exposed to the sun, in addition, the work of the immune system is weakened, the activity of lymphocytes decreases by 25-30%, the number of cells that are not involved in protecting the body from foreign substances increases.

2. Spiny layer - lies above the sprout layer
3. A granular layer consisting of several rows of cells containing keratohyalin in the protoplasm
4. The vitreous layer lies above the granular layer, formed by 3-4 rows of cells, filled with a special shiny substance eleidin.
5. The stratum corneum is the most superficial layer of the epidermis. Consists of flat keratinized (dead) cells. The latter turn into scales, which are gradually exfoliated on the surface of the epidermis, being replaced by new cells originating from the deeper layers of the epidermis, which leads to natural cleansing and renewal of the skin. For a more complete cleansing, periodic deep cleaning of the skin is recommended, using special cleansing scrubs or peels for this.

   Under the influence of some external and internal factors, the properties of the epidermis can change significantly. So, for example, with strong mechanical influences, with a lack of vitamin A, skin disease - psoriasis, the processes of keratinization and desquamation increase dramatically. When treated with hormones of the adrenal cortex (glucocorticoids), they slow down.

The skin itself (dermis), lying under the epidermis, is formed by fibrous connective tissue with many elastic fibers. Its fibers are intertwined with each other in different directions and form a dense network in which blood and lymphatic vessels, nerve receptors, sebaceous and sweat glands, hair bags lie.

The skin itself consists of two layers:

1. papillary layer - consists of loose connective tissue; it got its name because it carries papillae on its surface that protrude into the epidermis. Between the papillae are the interpapillary grooves. Nerve endings, blood capillaries and blind outgrowths of the lymphatic capillaries of the superficial (subepidermal) network of the skin lie in the papillae.
2. mesh layer - elastic and collagen fibers that are sent from the fascia to the subcutaneous tissue and the skin itself. Elastic fibers form a plexus under the papillae, which sends thin networks and individual fibers to the latter, causing skin elasticity.

Subcutaneous adipose tissue is the deepest layer of the skin. It is formed by loose connective tissue, the voids of which are filled with fatty lobules. This layer serves as a place for the deposition of fat, absorbs the action of various mechanical factors, softens bruises and serves as a "cushion" for internal organs, and provides skin mobility. In the subcutaneous tissue are numerous blood vessels and nerves that can hold up to 1 liter of blood. They serve as custodians of the blood, provide an even supply of nutrients to the skin and its muscles, and maintain a constant body temperature, protecting the body from cooling.

The structure and functions of the skin

Skin layers	Structure	Functions
The outer layer is the cuticle (epidermis)	Represented by stratified epithelial cells. The outer layer is dead, keratinized (hair and nails are formed from it), the inner layer consists of living dividing cells, contains the pigment melanin	Protective: does not pass microbes, harmful substances, liquids, solid particles, gases. Living cells of the epithelium form the cells of the stratum corneum; pigment melanin gives the skin color and absorbs ultraviolet rays, thus protecting the body; inner layer produces vitamin D
The inner layer is the actual skin (dermis)	Represented by connective tissue and elastic fibers, smooth muscle tissue. The skin contains blood capillaries, sweat and sebaceous glands, hair bags, receptors that perceive heat, cold, touch, pressure.	Regulation of heat transfer: when capillaries expand, heat is released, when narrowing, heat is retained. Allocation of moisture with salts, urea in the form of sweat. Skin respiration. Organ of touch, skin sense (especially at the fingertips). The hair on the skin of a person is rudimentary, but they retained the ability to rise. The sebum of the sebaceous glands lubricates the skin and hair, protects against microbes
Subcutaneous adipose tissue	Represented by bundles of connective tissue fibers and fat cells. Blood vessels, nerves pass through it into the skin	Heat preservation. Impact softening and protection of internal organs. Fat storage. The connection of the skin with the internal tissues of the body

Skin derivatives

Hair and nails are derivatives of the skin.

Hair cover the entire human body, except for the palms, lips, soles. There are three types of hair: long (mostly located on the head), bristly (eyebrows, eyelashes) and vellus (cover the rest of the skin). Hair is a horny formation, very durable and able to withstand a load of up to 100 g. Each hair has its own development cycle and life expectancy - from several months to 2-4 years. Every day, about 100 hairs fall out in a person, and at the same time the same number of hairs grows again, so their total number remains relatively constant. Hair roots - hair follicles, from where they continuously grow - lie in hair bags located in the skin itself. Hair grows at different rates: there are periods of active growth and periods of rest. On average, head hair grows 0.5 mm per day, and 15 cm per year.

Attached to the hair follicles are the muscles that raise the hair. Hair eyelashes, eyebrows, nasal openings do not have muscles. There are smooth muscle cells in the skin of the scrotum and in the skin around the nipple of the breast; they are not associated with hair bags, but form a muscular layer that lies in the papillary layer and partly in the subcutaneous tissue. The contraction of the smooth muscles of the skin leads to the appearance of small tubercles on it when cooled ("goosebumps"). This increases heat generation.

Hair color is determined by the presence of pigment, and shine and elasticity depend on the amount of fat secreted by the sebaceous glands, the ducts of which open into the hair bags.

Nails- dense horny plates located on the nail bed and protecting the terminal phalanges of the fingers. The average nail growth rate is 0.1 mm per day; in women, nails grow somewhat more slowly than in men. Complete restoration of the nail occurs on average in 170 days. The growth rate, color, pattern of nails are also largely determined by the state of the body.

The glandular apparatus of the skin

The glandular apparatus of the skin is represented by sebaceous and sweat glands.

The sebaceous glands are located on the scalp, face and upper back. During the day, they secrete up to 20 g of a secret called sebum. Sebum is composed of fatty acid esters, cholesterol, protein products, hormones and other substances, and serves as a lubricant for hair and skin. It softens the skin and gives it elasticity.

Sweat glands are found in almost all parts of the skin, but the pads of the fingers and toes, palms and soles, axillary and inguinal folds are especially rich in them. The total number of sweat glands reaches approximately 2.5 million. With the help of sweat glands, the skin performs the function of thermoregulation and excretory function. These glands produce sweat, it is released in the form of tiny droplets and quickly evaporates. On average, an adult loses from 700 to 1300 ml of sweat per day, and with it up to 500 kilocalories of heat. In addition, urea, salts and other substances come out with sweat.

The total surface of the glandular epithelium of the sweat and sebaceous glands is approximately 600 times greater than the surface of the epidermis.

Skin sensitivity

Skin receptors do not form special sense organs, but are scattered in the thickness of the skin over the entire surface of the body. They have a complex and varied structure. In most cases, these are multicellular bodies of various shapes, inside which a sensitive nerve fiber enters and branches. Between skin cells there are also bare nerve endings that perceive pain stimuli.

Excitation from the skin receptors along the centripetal nerves through the spinal cord enters the zone of skin sensitivity of the cerebral cortex.

The sensitivity of the skin to touch, pain, cold and heat helps the body to perceive the environment and better respond to changes in its conditions.

Skin thermoregulation

Due to thermoregulation, the temperature of the human body is relatively constant, despite fluctuations in the temperature of the external environment. Fat lubrication of the skin surface, subcutaneous fatty tissue and blood vessels of the skin prevent excessive heat or cold from the outside and excessive heat loss.

The significance of these formations in thermoregulation can be illustrated by the following case. In 1646, a festive procession took place in Milan, led by the "golden boy". The child's body was covered in gold paint. After the procession, the boy was forgotten and spent the whole night in a cold castle. Soon the boy fell ill and died. Gold paint caused the expansion of blood vessels in the skin, as a result, he lost a lot of heat, the body temperature dropped sharply. The cause of the death of the child was established only in the XIX century. In an experiment on two men whose bodies were covered with varnish, they showed that the cause was a violation of the body's thermoregulation.

The skin, participating in the processes of thermoregulation, protects the inner sphere from overheating or hypothermia. Through it, 80% of the heat generated in the body is released, mainly due to the evaporation of sweat. Both in winter and summer, the temperature on the surface of the skin of a healthy person is 36.6 ° C, and natural fluctuations do not exceed 2 ° C. When the ambient temperature drops, numerous blood vessels located in the skin narrow (we turn pale), blood flow to its surface decreases and, accordingly, heat transfer decreases, because. more blood enters the vessels of the internal organs, which contributes to the preservation of heat in them. The opposite processes occur when the temperature rises or during increased physical activity, when more heat is produced in the body. Then the blood vessels of the skin expand reflexively, more blood flows through them and heat transfer increases.

In extreme heat, when the body temperature is below the ambient temperature, the expansion of blood vessels can no longer enhance heat transfer. In this case, the danger of overheating is eliminated by sweating. Evaporating, sweat absorbs a large amount of heat from the surface of the skin (evaporation of 1 g of sweat takes 0.58 calories of heat). That is why the human body temperature does not rise even in the hottest weather. A person could withstand a temperature of 70-80 ° C, but at the same time he should have 9-16 liters of sweat in a few hours. An increase in body temperature is observed during many diseases. This is an indicator of a favorable course of the disease, a reflection of the body's active fight against infection and a natural reaction. Elevated body temperature accelerates chemical processes, increases metabolism, increases the activity of leukocytes, that is, mobilizes the body's defenses.

Heatstroke- this is a violation of the functions of the body when it is overheated, as a result of the cessation of heat transfer due to high humidity and high temperature. With heat stroke, headache, dizziness, tinnitus, flickering in the eyes, increased heart rate and respiration, dilated pupils, impaired movement, nausea and vomiting, loss of consciousness, convulsions, fever are observed.

Sunstroke occurs as a result of prolonged exposure to the direct rays of the sun with an uncovered head. At the same time, the vessels of the brain expand, cerebral edema develops, intracranial pressure rises, and the temperature of the human body rises sharply.

In case of heat or sunstroke, it is necessary to call an ambulance, and before it arrives, the patient must be transferred to a cool place, raise his head and unbutton his clothes, put cold on his head and heart area and give him cool water to drink.

frostbite manifested in loss of sensitivity in the affected area of ​​the skin, in its whitening. In this case, you must immediately grind the whitened area in order to restore blood circulation in it. With severe frostbite, as with a severe burn of the skin, it is necessary to cover the affected area of ​​\u200b\u200bthe skin and immediately contact a medical institution.

Alcohol violates the mechanisms of thermoregulation, which contributes to hypothermia of the body and the occurrence of colds and infectious diseases.

In addition to the entrance exam requirements

• Hardening of the body (based on the book: Laptev A.P. The ABC of hardening, M., FiS, 1986)

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Leather- this is one of the human organs that perform a protective role and a number of biological functions. The entire human body is covered with skin, and depending on height and weight, its area is from 1.5 to 2 m 2, and its weight is from 4 to 6% of the human mass (excluding hypodermis).

The article discusses the structure of human skin, its structure and functions of each layer, how skin cells are formed and renewed and how they die.

Skin functions

The main purpose of the skin- This is of course protection from external environmental influences. But our skin is multifunctional and complex and takes part in a number of biological processes in the body.

The main functions of the skin:

• mechanical protection- the skin prevents soft tissues from mechanical impact, radiation, microbes and bacteria, foreign bodies from entering the tissues.
• UV protection- under the influence of solar treatment, melanin is formed in the skin as a protective reaction to external adverse (with prolonged exposure to the sun) effects. Melanin causes temporary darkening of the skin. A temporary increase in the amount of melanin in the skin increases its ability to retain ultraviolet (delays more than 90% of radiation) and helps neutralize free radicals formed in the skin when exposed to the sun (acts as an antioxidant).

• thermoregulation- participates in the process of maintaining a constant temperature of the whole organism, due to the work of the sweat glands and the thermal insulating properties of the layer hypodermis consisting mainly of adipose tissue.
• tactile sensations- due to nerve endings and various receptors close to the skin surface, a person feels the influence of the external environment in the form of tactile sensations (touch), and also perceives temperature changes.
• maintaining water balance- through the skin, the body, if necessary, can excrete up to 3 liters of fluid per day through the sweat glands.
• metabolic processes- through the skin, the body partially removes by-products of its vital activity (urea, acetone, bile pigments, salts, toxic substances, ammonia, etc.). Also, the body is able to absorb some biological elements from the environment (trace elements, vitamins, etc.), including oxygen (2% of the total gas exchange of the body).
• vitamin synthesisD- under the influence of ultraviolet radiation (sun), vitamin D is synthesized in the inner layers of the skin, which is subsequently absorbed by the body for its needs.

Skin structure

The skin is made up of three main layers:

• epidermis(epidermis)
• dermis(corium)
• hypodermis(subcutis) or subcutaneous adipose tissue

In turn, each layer of the skin consists of its own individual structures and cells. Consider the structure of each layer in more detail.

Epidermis

Epidermis- this is the top layer of the skin, formed mainly on the basis of keratin protein and consisting of five layers:

• horny- the uppermost layer, consists of several layers of keratinized epithelial cells, called corneocytes (horny plates), which contain insoluble protein keratin
• brilliant- consists of 3-4 rows of cells, elongated in shape, with an irregular geometric contour, containing eleidin, from which keratin
• grainy- consists of 2-3 rows of cells of a cylindrical or cubic shape, and closer to the surface of the skin - diamond-shaped
• prickly- consists of 3-6 rows spiny keratinocytes, polygonal shape
• basal- the lowest layer of the epidermis, consists of 1 row of cells called basal keratinocytes and having a cylindrical shape.

The epidermis does not contain blood vessels, so the intake nutrients from the inner layers of the skin to the epidermis going on at the expense diffusion(penetration of one substance into another) tissue(intercellular) liquids from the dermis into the layers of the epidermis.

interstitial fluid It is a mixture of lymph and blood plasma. It fills the space between cells. Tissue fluid enters the intercellular space from the terminal loops of blood capillaries. There is a constant exchange of substances between the tissue fluid and the circulatory system. Blood delivers nutrients to the intercellular space and removes waste products of cells through the lymphatic system.

The thickness of the epidermis is approximately equal to 0.07 - 0.12 mm, which is equal to the thickness of a simple paper sheet.

In some parts of the body, the thickness of the epidermis is slightly thicker and can be up to 2 mm. 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.

Skin acidity pH is 3.8-5.6.

How does human skin cells grow?

In the basal layer of the epidermis cell division occurs, their growth and subsequent movement to the outer stratum corneum. As the cell matures and approaches the stratum corneum, keratin protein accumulates in it. Cells lose their nucleus and major organelles, turning into a "pouch" filled with keratin. As a result, the cells die, and form the uppermost layer of the skin from keratinized scales. These scales are shed over time from the surface of the skin and replaced by new cells.

The whole process from the origin of the cell to its exfoliation from the surface of the skin takes an average of 2-4 weeks.

Skin permeability

The scales that make up the uppermost layer of the epidermis are called - corneocytes. The scales of the stratum corneum (corneocytes) are interconnected by lipids consisting of ceramides and phospholipids. Due to the lipid layer, the stratum corneum is practically impermeable to aqueous solutions, but solutions based on fat-soluble substances are able to penetrate through it.

Color of the skin

Cells within the basal layer melanocytes, which highlight melanin- a substance that determines the color of the skin. Melanin is formed from tyrosine in the presence of copper ions and vitamin C under the control of hormones secreted by the pituitary gland. The more melanin contained in one cell, the darker the color of human skin. The higher the melanin content in the cell, the better the skin protects against ultraviolet radiation.

With intense exposure to the skin of ultraviolet radiation, the production of melanin sharply increases in the skin, which provides the skin with a tan.

The effect of cosmetics on the skin

All cosmetics and procedures, designed for skin care, affect mainly only the top layer of the skin - epidermis.

Dermis

Dermis- this is the inner layer of the skin, from 0.5 to 5 mm thick, depending on the part of the body. The dermis is made up of living cells., supplied with blood and lymphatic vessels, contains hair follicles, sweat glands, various receptors and nerve endings. The basis of the cells in the dermis is fibroplast, which synthesizes the extracellular matrix, including collagen, hyaluronic acid and elastin.

The dermis is made up of two layers:

• reticulate(pars reticularis) - extends from the base of the papillary layer to the subcutaneous fatty tissue. Its structure is formed mainly from bundles of thick collagen fibers located parallel to the surface of the skin. The mesh layer contains lymphatic and blood vessels, hair follicles, nerve endings, glands, elastic, collagen and other fibers. This layer provides the skin with firmness and elasticity.
• papillary (pars papillaris), consisting of an amorphous structureless substance and thin connective tissue (collagen, elastic and reticular) fibers that form papillae that lie between the epithelial ridges of spiny cells.

Hypodermis (subcutaneous adipose tissue)

Hypodermis- This is a layer consisting mainly of adipose tissue, which acts as a heat insulator, protecting the body from temperature changes.

The hypodermis accumulates nutrients necessary for skin cells, including fat-soluble vitamins (A, E, F, K).

The thickness of the hypodermis varies from 2 mm (on the skull) to 10 cm or more (on the buttocks).

With inflammatory processes in the hypodermis that occur during certain diseases, cellulite occurs.

Video: Skin structure

• The area of ​​​​the entire skin of an adult is 1.5 - 2 m 2
• One square centimeter of skin contains:

• over 6 million cells
• up to 250 glands, of which 200 sweat and 50 sebaceous
• 500 different receptors
• 2 meters of blood capillaries
• up to 20 hair follicles

• With an active load or high external temperature, the skin can release more than 3 liters of sweat per day through the sweat glands.
• Due to the constant renewal of cells, we lose about 10 billion cells a day, this is a continuous process. Over the course of a lifetime, we shed about 18 kilograms of skin with keratinized cells.

Skin cells and their function

The skin is made up of a large number of different cells. To understand the processes occurring in the skin, it is good to have a general idea of ​​the cells themselves. Consider what the various structures are responsible for (organelles) in a cage:

• cell nucleus- contains hereditary information in the form of DNA molecules. In the nucleus, replication occurs - doubling (multiplication) of DNA molecules and the synthesis of RNA molecules on a DNA molecule.
• kernel shell- provides exchange of substances between the cytoplasm and the nucleus of the cell
• cell nucleolus- it synthesizes ribosomal RNA and ribosomes

• cytoplasm- a semi-liquid substance that fills the interior of the cell. Cellular metabolism takes place in the cytoplasm
• ribosomes- necessary for the synthesis of proteins from amino acids according to a given matrix based on genetic information embedded in RNA (ribonucleic acid)
• vesicle- small formations (containers) inside the cell in which nutrients are stored or transported
• apparatus (complex) Golgi is a complex structure that is involved in the synthesis, modification, accumulation, sorting of various substances inside the cell. It also performs the functions of transporting substances synthesized in the cell through the cell membrane, beyond its limits.
• mitochondrion- the energy station of the cell, in which the oxidation of organic compounds occurs and the release of energy during their decay. Generates electrical energy in the human body. An important component of the cell, the change in activity of which over time leads to aging of the body.
• lysosomes- necessary for the digestion of nutrients inside the cell
• interstitial fluid fills the space between cells and contains nutrients

Leather I Skin (cutis)

The skin is involved in the processes of immunity. Distinguish between non-specific, 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 small amounts -.

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) . In case of insufficiency of the function of the kidneys or liver 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 exchange 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 genital organs, 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 body. 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 a galvanic skin reflex, a 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 slightly 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 in the function 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 K. of the person, a front 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. 5 ), 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. Characterized by slow and a tendency to recurrence after excision.

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. 9 ). 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 tan 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 injuries 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. With an 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 tendency to growth, 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.

Rice. 6. Dermatofibroma: a large rounded nodule in the lower part of the auricle.

In infants, exudative-catarrhal diathesis 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 needs to 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 careful 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 wrapping, 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, mashed green apples, 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 (low-fat), cottage cheese, kefir and other lactic acid products, buckwheat, rice and oatmeal, vegetarian soups, vegetables, fruits.

The human skin has a complex structure. In different places of the body, its thickness is different and varies from 0.1 to 4 mm. The thickest is the skin of the neck, back, skull, thighs, palms and feet. The appearance and condition of the skin undergo changes depending on age, general condition of the body, nutrition, external influences, etc. Its color and elasticity depend on living conditions, gender, age, profession, season, climate, race, hereditary characteristics, etc. On the skin surface, a fine network of tiny grooves is visible to the naked eye, due to the special anatomical structure of the skin.

The skin is made up of three main layers: outer (epidermis), middle (dermis, or true skin) and inner (hypoderm, or subcutaneous layer).

Epidermis consists of several layers of microscopically small cells. The cells of the deepest layer, called the germinal layer, constantly multiply and are gradually forced out to the surface of the skin. Over time, they are filled with horny substance and form the most superficial layer of the epidermis. Horny cells are continuously shedding and falling off, but this process is very slow and goes unnoticed in a healthy person.

Dermis (true skin) It consists of fine fibers of connective tissue, collected in bundles, and of special elastic (collagen) fibers that give elasticity to the skin. The skin of young people is smooth, taut and elastic, as it is rich in elastic fibers. Over time, however, these fibers become thinner, their elasticity and number are lost, which is why in old age the skin relaxes, becomes inelastic, wrinkled, which is especially noticeable on the face and neck.

The dermis also contains a dense network of blood vessels and nerves. It also contains many muscle fibers, which are connected to the hair root with their inner end. When they contract, the hair rises and the skin becomes rough (goose bumps).

Hypodermis (subcutaneous layer) consists of intertwined bundles of connective tissue fibers. They connect the dermis to the underlying tissues. When deviated, the bundles form a weak network filled with grains of subcutaneous fat. This fat gives a rounded shape to the body and, being a poor conductor of heat, protects it from cooling. Fat is unevenly distributed throughout the body, and its amount depends on age, gender, nutrition, physical stress, etc. In women, it accumulates most in the abdomen, thighs and buttocks.

The dermis and hypodermis also contain a dense network of lymphatic vessels, nerves, and nerve fibers. Free nerve endings perceive pain. Other nervous apparatuses of various devices perceive touch, pressure, heat or cold, itching, burning and tickling.

Skin color is determined by several factors. The most important of these is the brown pigment melanin, which is found in the form of grains in the cells of the deepest layer of the epidermis. The amount varies from person to person. Dark-skinned people have more melanin than fair-skinned people.

The skin of children, girls and young people contains comparatively less pigment and is thinner. It has more blood vessels and therefore it is more pink, delicate and fresh. Another factor that determines the color of the skin is transparency, and this, in turn, depends on the thickness of the skin. With age, the epidermis thickens, coarsens and the skin becomes thinner, irreversible aging processes occur in it. Skin color also depends on the pinkish-red color of the blood pigment (hemoglobin) in the capillaries and on the yellowish color of the pigment of the horny substance (keratin) located in the epidermis. Under the influence of ultraviolet rays (solar or quartz lamps), the amount of melanin rapidly increases and the harmful penetration of these rays into the depths of the body decreases.

skin glands. There are two types of glands - sweat and sebaceous.

sweat glands are a thin tube that opens on the surface of the skin into a separate sweat pore. The inner end of the tube is curled in the form of a ball. Human skin contains from 2 to 15 million sweat glands, distributed unevenly in the skin. The skin of the palms, armpits, inguinal folds, feet, forehead and back is richest in sweat glands. The release of sweat depends on the state of the nervous system, which determines the sharp sweating with severe fright or excitement.

Sebaceous glands are in the dermis. They adjoin the hair and open into the hair canal. Human skin contains about 900,000 sebaceous glands, which secrete 2-3 g of sebum daily. They are scattered throughout the body (with the exception of the palms and feet), but are most densely located on the head, face, back and chest. With abundant fat secretion, the skin and hair become oily, shiny and elastic. With reduced secretion, the skin is dry, rough, even cracks sometimes form, and the hair is dry and brittle.

Hair and nails. The hair consists of a shaft, a root and a bulb. The shaft is the part that is outside the skin. The hair root is hidden in the skin and starts from the bulb. Hair growth is determined by the reproduction of bulb cells. Each bulb is associated with a nerve branch and blood vessels, on which its condition depends.

The hair cells of young people contain a pigment that determines the color of the hair. In adults, this pigment is gradually replaced by air bubbles, which gives the hair a white color.

There is a relationship between hair color and thickness. Blondes have the thinnest hair (0.04mm). Thicker hair in brown-haired women and brunettes. Blondes have about 140,000 hairs on their heads, brown-haired women have about 110,000, and brunettes have about 100,000 hairs. Hair grows constantly, but unevenly. They grow faster in spring and autumn. In one month, hair grows by 1 - 1.5 cm. Over a certain period - from several months (for eyelashes) to several years (for head hair), hair falls out and a new one grows in its place. Different people lose from 20 to 120 hairs a day. The number of hair loss is individual.

Nails grow by multiplying the cells of the basal part. On the arms in one week they grow by 1 mm, and on the legs in 3-4 weeks by 1 mm. The nails of young people grow faster than adults, and faster in summer than in winter. The growth and thickness of nails, and hence their strength, depend on the state of health of the body, profession, gender, age, etc.

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