Skin and its structure. Skin care. Cleanliness and excessive sterility

Leather I Skin (cutis)

The skin is involved in immune processes. There are nonspecific, independent of previous infections or vaccinations, which are formed when the skin is exposed to UV radiation, and specific, which develops when agents to which it is especially sensitive, such as the causative agent of anthrax, penetrate into the skin. The skin has low electrical conductivity, and its electrical resistance, especially the stratum corneum, is high. Electrical resistance decreases in damp areas of soil, especially when increased sweating, as well as in individuals with a predominant tone of the parasympathetic nervous system. Electrical resistance depends on physical properties K., the functional state of the sebaceous and sweat glands, blood vessels of the K., nervous and endocrine systems.

Through the skin (excluding K. heads) it releases 7-9 per day G carbon dioxide and absorbs at t° 30° 3-4 G oxygen, which accounts for about 2% of all gas exchange in the body. Skin intensifies with increasing ambient temperature, during physical work, increasing 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 practically do not occur in mammals due to the presence of the stratum pellucida and stratum corneum impregnated with lipids, which 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 blister gases such as mustard gas and lewisite, do not penetrate through the gas. Morphine, ethylene glycol monoethyl ether, dimethyl sulfoxide and other substances are easily absorbed, in small quantities.

K.'s excretory function is carried out by the sweat and sebaceous glands. The amount of substances secreted through the sweat glands depends on gender, age, and topographical features of the skin (see Sweat glands , Sebaceous glands) . In case of 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 the bloodstream under the control of the central nervous system. 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 released per day ml sweat. sweat depends on the ambient temperature, the state of the body, the intensity of the basal metabolism, etc. Sweating increases with increasing ambient temperature, dry air, and hyperemia of the body; during sleep or anesthesia it sharply decreases and even stops. The sebaceous glands consist of 2/3 water, and 1/3 analogues of casein, cholesterol and some salts. With it, free fatty and unsaponifiable acids, metabolic products of sex hormones, etc. are released. Maximum sebaceous glands are observed from puberty to 20-25 years. The skin plays the role of a filter, preventing excessive release of water to the surface.

The pigment-forming function of K. is the production 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 in the form of a melanoprotein complex. Melanogenesis is regulated by pituitary melanocyte-stimulating hormone. skin is caused mainly by the deposition of melanin. However, human blood contains other pigments: melanoid, oxyhemoglobin, and reduced hemoglobin. Violation of pigment formation leads to hyperpigmentation (for example, with Addison's disease) or depigmentation (etc.).

Among the nerve fibers innervating the blood vessels of the blood vessels, adrenergic and cholinergic fibers are distinguished. Neurohumoral factors constantly exert a regulatory influence on blood vessels. , norepinephrine and the posterior lobe of the pituitary gland cause vasoconstriction, and acetylcholine and androgens dilate them. Normally, most of the blood vessels of the capillary are in a semi-contracted state, the speed of blood flow in the capillaries is insignificant; 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 impairment.

K plays a very important role in the thermoregulation of the body. The production of thermal energy in the body thanks 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. Fatty lubrication of the skin's surface and 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 the sympathetic system participate; 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, intensity of sweating and sebum secretion, muscle work and the age of the person. A person produces about 2,600 calories of heat per day, children 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 normal conditions.

The skin plays a big role in metabolic processes. In addition to gas exchange carried out during skin respiration, interstitial carbohydrate, protein, fat, salt and vitamin metabolism occurs in the bloodstream. In terms of the intensity of water, mineral and carbon dioxide metabolism, blood cells are slightly inferior to the liver and muscles. The body accumulates and releases large amounts of water faster and easier than other organs. Twice as much water is released through the lungs as through the lungs. The processes of metabolism and acid-base balance depend on many factors, including a person’s nutrition (for example, if acidic foods are abused, the sodium content in potassium decreases). K., especially subcutaneous tissue, is a powerful depot of nutritional materials that are consumed by the body during fasting.

The skin is a huge receptor field through which the body communicates with the environment. It is involved in various reflex reactions - to cold, high temperature etc., as well as in the plantar, pilomotor and other reflexes. Exteroceptors K. perceive various external irritations, which in the form of a nerve impulse are transmitted 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 pads of the fingers, in the external genitalia, and in the area of ​​the nipples, where there is the largest number of highly differentiated nerve endings. Its variant, obviously, is hair sensitivity K., which occurs when touching the hair and depends on irritation of the complex basket nerve plexus of the hair follicle. Complex types of sensitivity include the sense of place (localization), stereognostic, two-dimensional-spatial and the sense of separation (discriminative sensitivity).

Different parts of the brain do not perceive the same thing in the same way. It is believed that at 1 cm 2 The skin contains 100-200 pain points, 12-15 cold points, 1-2 heat points and about 25 pressure points. Most skin receptors are polyvalent in function. Influenced various factors environment, the number of functioning sensory receptors may change, developing, especially to tactile and temperature stimulation. weakest to painful stimuli.

Unconditioned and conditioned skin cells play an important role in the life of the body. Newborns have innate unconditioned skin reflexes - sucking and grasping. There are cutaneous reflexes (irritation and response occurs to K.), muscle-hair, unconditioned vasomotor - reflex Dermographism , vasomotor reactions in response to intradermal administration of adrenaline, histamine, etc. The musculocutaneous reactions include the abdominal, cremaster reflex, and plantar reflex. There are also galvanic skin reflex, a reflex to. Impulses coming from skin receptors maintain normal muscle function. Skin-muscle reflexes are of great importance in labor activity humans, 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 stimulation of the body is accompanied by changes in the secretion of the pituitary gland, increased release of adrenaline, inhibition of the digestive process, and changes in the biocurrents of the brain. There are also skin-respiratory, skin-vascular and other skin-visceral reflexes. Well known are reflexive, 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), “goose bumps”. The same conditioned reflex mechanism underlies 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 the skin deprived of water and fat (see Collagens) . Reticulin and elastin are contained in K. in much smaller quantities; they form the basis of reticulin and elastic fibers of the dermis, connective tissue membranes of the sebaceous and sweat glands, and are part of the membrane of hair follicles. Keratin is the basis of the stratum corneum. The process of formation of the stratum corneum in the epidermis ends in its cells, which begins in the basal epidermocytes. The skin also contains protein breakdown products: uric acid, creatinine, ammonia, etc. There are three times more of them in the skin (up to 150 mg%) than in blood; Especially a lot of them accumulate in pathologically altered areas of the skin when decay processes predominate. The process of formation of the horny substance is regulated by genetic mechanisms, as well as the endocrine and immune systems. Disturbances of keratinization () are observed with skin tumors, Darier's disease, etc. A significant part of K. cells, like other cells of the body (especially their nuclei), are made up of nucleoproteins and (and RNA).

Carbohydrates contain glycogen and glycosaminoglycans. When glycosaminoglycans depolymerize (for example, when hyaluronidase activity increases), the gels they form decrease, etc. K. increases for microorganisms and various toxic products; K. is formed and accumulates in mast cells; it plays a large role in the regulation of microcirculatory processes.

The skin and its surface contain a variety of lipids. Neutral fibers make up the bulk of subcutaneous tissue. They are dominated by the most fusible triglyceride - triolein (up to 70%), and therefore human triglyceride 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. The mineral components of K. account for from 0.7 to 1% of its dry weight, and in subcutaneous tissue - about 0.5%. Skin is an important depot of sodium, potassium, calcium and other trace elements. For the normal state of K., the most important are zinc, arsenic, and some others, which are part of enzymes, vitamins or play the role of activators of biological processes.

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

Protein metabolism disorders lead to the development of gout (Gout) , Amyloidosis , Porphyria , skin mucinosis (deposition of mucin in K.) and other diseases with pronounced changes in K. Impaired lipid metabolism is the cause of lipidosis (Lipidosis) . Changes in carbohydrate metabolism, accompanied by accumulation in the blood and blood, lead to necrobiosis lipoidica (Necrobiosis lipoidica) , contribute to the occurrence of furunculosis (see Furuncle , chronic Pyoderma and other diseases K. Deviations and enzyme activities are noted in dermatoses, such as eczema (Eczema) , Neurodermatitis , Psoriasis .

Metabolism in blood cells is influenced by nervous and hormonal factors. Dysregulation of biochemical processes at the cellular and intracellular levels play an important role in the occurrence of skin diseases. In particular, an important pathogenetic mechanism of psoriasis is a violation of the cellular regulatory system of adenyl cyclase - cyclic.

Vitamin A deficiency plays a role in the development of ichthyosis a , seborrhea (Seborrhea) , Devergie disease (Devergie disease) , nail dystrophy (see Nails), etc. Lack of vitamin PP causes the development of pellagra (Pellagra) with severe skin damage, and vitamin C - scurvy (scurvy) . The pathogenesis of neurodermatitis is associated with a lack of B vitamins, especially B6. 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 and inguinal-femoral folds, sweat has a slightly alkaline or slightly acidic reaction (pH 6.1-7.2). Pronounced shifts in pH towards an alkaline reaction contribute to the occurrence of mycoses (Mycoses) . In addition to the biochemical processes common to the body, transformations that are unique to it occur in skin: the formation of keratin, melanin, sebum and sweat.

With slowly developing acidosis, intercellular edema occurs (), manifested by multi-chamber vesicles (see Rash) . When intercellular connections are disrupted, single-chamber intraepidermal blisters are formed. Coagulative and collicative cell death (see Necrosis) leads to erosion that heals without a scar, or ulcer (Ulcer) , penetrating into the connective tissue part of the skin and healing with the formation of a scar.

Often inflammation of the skin is accompanied by the development of purulent exudate and the formation of pustules (see Rash) . With productive inflammation, a cellular papule or tubercle is formed with a dermal papule (with specific inflammation). , resolving without necrosis ends with cicatricial atrophy, and disintegrating - with a scar. Special group inflammatory processes constitute chronic granulomas. The inflammatory infiltrate in the dermis, disrupting, 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. K. inflammation can occur as a result of increased sensitivity to a strictly defined antigen (see Allergy) , in other cases it is not specific and is caused by any strong irritant.

K.'s condition is associated with the condition of the whole organism. Nephropathy is often accompanied by so-called cutaneous uremia, caused by azotemia, oxalemia, and urea retention. Foci of chronic infection (in the tonsils, teeth, etc.) can cause a number of dermatoses. Often the background for the occurrence and development of eczema, urticaria (urticaria) , Neurodermatitis, circular hair loss are neurovegetative disorders. After mental trauma, red flat skin, psoriasis, etc. often appear. The skin reacts to disruption of the endocrine system. Thus, dysfunction of the thyroid gland contributes to the development of skin myxedema, excessive sweating, itching, urticaria, eczema, etc.; dysfunction of the ovaries - chloasma (see Dyschromia of the skin) ; 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 exposure, 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 determine big number skin diseases (about 2 thousand different forms), the classification of which has not been fully developed (see Dermatoses) .

A large group consists of K. lesions associated with hereditary factors (see Genodermatoses) or which are congenital malformations of the fetus as a result of adverse effects during the processes of embryogenesis (intrauterine intoxication, infections, circulatory disorders, etc.) K. caused by genetic factors are very diverse ; They often wear family clothes. Congenital deformities and anomalies of the body's development that are not associated with genetic factors are more rare. Some of the malformations of K. are abortive manifestations of more complex birth defects: swimming membranes are 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 healing of congenital gaps, additional breast nipples- incomplete gynecomastia, etc.

With other congenital anomalies of the fetus, the main developmental disorders of the fetus are concentrated in the fetus. Thus, congenital absence is known - the fetus, accompanied by underdevelopment of the appendages of the fetus and teeth (congenital ectodermal). Congenital aplasia of the skin (defect of the epidermis and dermis) is characterized by the presence of up to 10 ulcers in the child at birth. cm in the parietal, occipital or posterior auricular region of the head. Congenital defect K. is formed in the fetus in the form of a bullous lesion (blister); by the time the child is born, a blister is formed in place of the blister. Gradually it closes, leaving behind scar atrophy. Congenital aplasia K. can be combined with a defect in the bones of the skull. With other types of aplasia K., areas devoid of skin can be located on the torso and limbs. They are covered with a thin membrane through which the underlying organs and tissues are clearly visible.

Congenital anomalies such as hyperelastic rubber, desmogenesis imperfecta, and pachyderma are associated with changes in connective tissue. Developmental defects include a variety of clinical forms birthmarks, angiomas, lymphangiomas.

A large group consists of diseases caused by mechanical damage (for example, abrasion, callus). , 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.

K.'s inflammatory lesions may be based on allergic reactions of the body, changes in the nervous and endocrine systems (see Toxidermia , Hives , Eczema , Neurodermatitis , Pruritus, etc.). The skin is often affected by diffuse connective tissue diseases (Diffuse connective tissue diseases) , Sarcoidosis , skin vasculitis (skin vasculitis) , metabolic disorders in the body (see Lipidoses , Amyloidosis , Calcinosis , Xanthomatosis, etc.).

Pathological processes in skin, associated primarily with individual morphological structures of the skin - see Hair , Nails , Sweat glands , Sebaceous glands .

Skin tumors. According to the WHO histological classification (1980), skin tumors are distinguished: benign, premalignant (precancerous) skin diseases, tumors with locally destructive growth, and malignant tumors. Based on their origin, skin tumors are classified into epithelial, pigment and connective tissue tumors.

Skin developmental defects. These include papillomatous, comedo nevus, epidermal cyst, pilar cyst, dermoid cyst (see Dermoid) , whiteheads, atheroma, etc.

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

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

Seborrheic keratosis, or seborrheic keratosis, occurs more often in older people (after 40 years); localized in closed areas of the skin, such as the torso ( rice. 3 ). Characterized by the appearance of sharply hyperpigmented (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 can 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 and is localized in the external genitalia, as well as in the perineal area. It has a soft consistency and large sizes (4-6 cm). It usually grows slowly.

Eccrine poroma is a tumor of the intradermal part of the eccrine sweat gland duct. It is localized mainly on the plantar surface of the feet, on the palms, and on 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. The eccrine poroma is painless on palpation; may ulcerate.

Papillary syringocystadenoma () - excretory duct of the sweat gland. It is, as a rule, a nevoid formation. It is rare, usually in children and adolescents. It is most often located on the scalp, neck, inguinal and axillary folds. It has the appearance of single or multiple tumor-like formations of 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. It is rare, more often observed in young men. It is localized, as a rule, on the skin of the face and the anterior surface of the body. It is dark yellow or bluish-red in color, dense in consistency, sometimes painful on palpation.

Benign epithelial tumors of the hair follicle include cylindrima, trichoepithelioma, etc. are 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 and a tendency to relapse after surgical excision.

Trichoepithelioma can be multiple or single. The multiple 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. The single form occurs mainly in adults - trichoepithelioma itself. 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 appearance of single, dense, round nodules or nodes, sometimes sitting on a stalk.

Fibroma can appear on any part of the K. There are hard and soft fibromas. Solid fibroma has a wide base, dense consistency, smooth surface, normal skin color or slightly pink. This is a limitedly mobile tumor that rises above the surface of the tumor. Soft fibroma can be multiple or single. It is localized mainly on the neck, front surface of the chest, in the inguinal folds and armpits. It looks like a pouch-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 the upper and lower extremities. dense consistency, dark brown color, round shape, deeply located in the K. often does not protrude above its surface.

Dermatofibrosarcoma protuberans is a locally invasive tumor. It occurs more often in men in the shoulder girdle area, on the head. It can be single or multiple. protrudes above the surface of the K., has a smooth, tuberous surface that can ulcerate. Characterized by slow and tendency to develop relapses after excision.

Hemangioma develops from blood vessels. There are capillary ( rice. 7 ), arterial, arteriovenous and cavernous ( rice. 8 ) shapes (see Blood vessels , tumors). A special form of hemangioma is pyogenic granuloma ( rice. 9 ). It occurs as a result, and is localized on the face, often in the lip area, and on the upper extremities. It is a dark red tumor on a stalk or broad base with an erosive surface.

Lymphangioma is a tumor arising from the lymphatic vessels. It is often detected from birth. Localized on any area of ​​the skin. Combined 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 can be a manifestation of lymphostasis, sometimes appearing after an infectious disease (for example, erysipelas).

Leiomyoma is a tumor arising from the muscles that lift the hair. There are 3 clinical types: 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) round in shape, 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 rich red color, dense elastic consistency. It is often localized in the area of ​​large joints.

Lipoma - tumor of adipose tissue in the form of single or multiple foci. They are localized in any area of ​​the skin, rising above its surface. It is usually large in size (up to 10 cm in diameter), doughy consistency, normal skin color. A variant of lipoma is symmetrical multiple (Dercuma), characterized by the appearance predominantly on the upper extremities of lesions that are painful on palpation.

Benign pigmented tumors of K. include various forms of pigmented nevus and. Pigmented nevi are characterized by the appearance on the skin of spots or neoplasms consisting of nevus cells. They arise 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 round in shape, with a diameter of 1 cm and more ( rice. 10 ). The surface of a pigmented nevus is often smooth, but sometimes there are papillary warty growths. In some cases, a large nevus occupies a significant part of the body, face, neck, or limbs and represents a cosmetic defect (giant pigmented nevus). Hair often grows on its surface. Sometimes the nevus is blue in color - a blue nevus. It is more common in women on the face and forearms. A variety of blue nevus is Mongolian. It occurs predominantly in people of Asian origin 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 Asian women. It can be 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). There is also Sutton's nevus (Sutton's disease) - 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 (when localized outside the nipple and areola of the mammary gland), which are rare.

Solar keratosis occurs as a result of excessive sun exposure. Moreover, 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 in size cm in diameter, covered with dense gray scaly crusts. Affected areas may develop Bowen's disease or squamous cell carcinoma.

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

The lesion grows slowly along the periphery, its surface is often ulcerated, there are areas of atrophy on it, which, together with scales and cortical layers, gives the tumor a mottled appearance. People suffering from Bowen's disease are often diagnosed with cancer of internal organs.

Paget's disease, when localized outside the nipple and areas of the mammary gland, is characterized by limited foci of maceration and oozing, 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 (sebaceous and sweat glands). This is the most common epithelial tumor of K. It is observed mainly in old age. Characterized by invasive growth; extremely rarely metastasizes. Clinical manifestations are varied. There are superficial (the most favorable form), cystic, ulcerative, scleroderma-like and pigmented forms of basal cell carcinoma.

Superficial basalioma is a limited spot, along the periphery of which there is a ridge consisting of individual nodules (“pearls”). It is most often localized in open areas of the body exposed to insolation and prolonged mechanical irritation. In people with fair skin, multiple lesions may occur that merge into large plaques covered with scales ( rice. 12 ). Often, spontaneous growth occurs in the center of the plaque, and tumor growth occurs along the periphery (self-scarring basal cell carcinoma).

With cystic basal cell carcinoma, the lesion is often single, sharply demarcated from the surrounding tissue, bright pink in color, and doughy consistency; There are often telangiectasia on the surface. It is localized mainly on the skin of the face (around the eyes, nose).

Ulcerative basalioma ( rice. 13. 14 ) can develop from superficial or cystic. It occurs most often on the chin, at the base of the nose or the inner corner of the eye. 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 basal cell carcinoma are a corrosive ulcer ( rice. 15 ) and ulcus terebrans (penetrating ulcer). With ulcus terebrans, the process extends to the periphery. In some cases, papillomatous growths (verrucous-ulcerative basalioma) appear on the ulcerated surface.

With scleroderma-like basalioma, plaques of dense consistency with clear boundaries form on the face and upper body. They resemble lesions of scleroderma, in which an erythematous rim is noted along the periphery of the lesion. In contrast to scleroderma, with scleroderma-like basal cell carcinoma, a roll-like edge and single nodules - “pearls” - are found along the periphery of the lesion.

Pigmented basal cell carcinoma has a darker color (from yellowish-brown or bluish-brown to dark brown or black), which is due to the presence of melanin in the cytoplasm of tumor cells.

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

For malignant skin tumors include squamous cell carcinoma, pigmented tumors - precancerous Dubreuil and melanoma (Melanoma) . Squamous cell carcinoma K. is an epithelial malignant tumor. It occurs more often in places of constant irritation, mechanical, against the background of long-term non-healing trophic ulcers, fistulas, radiation damage to the skin, and can also develop from lesions characteristic of Bowen's disease, xeroderma pigmentosum, 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 roller-shaped edges is formed. slowly but steadily growing and bleeding. In the papillary form, single hard nodules resemble a wart or keratoacanthoma, merging with each other into large lesions resembling cauliflower ( rice. 16 ). Squamous cell keratinizing cancer is characterized by infiltrative growth into the underlying tissues, metastasizing to the lymph nodes and lymphatic vessels, and in advanced cases, to the blood vessels.

Dubreuil's precancerous melanosis is a slow-growing tumor that usually occurs after age 30, most often in women. It is localized, as a rule, in open areas of the K. It looks like 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 tumor color (darkens), the development of papillomatous growths on the surface or the appearance of areas of atrophy indicate its transformation into melanoma.

Treatment. Most K. tumors are not accompanied by noticeable subjective sensations. When neoplasms appear, the patient should be referred for consultation to an oncologist or dermatologist (oncologist), who will determine, based on medical history, clinical signs and the results of histological and cytological studies and conducts. For benign tumors of K., surgical treatment (tumor removal) is carried out if the tumor is localized in places subject to trauma, as well as at the request of the patient (for example, in case of a cosmetic defect). Pre-malignant diseases are subject to mandatory treatment. For this purpose, surgical procedures are used, incl. electrosurgical, cryodestruction, radiation therapy (Radiation therapy) , laser (see Lasers) . According to indications, various cytostatic drugs (5-fluorouracil, ftorafur, prospidin, etc.) are also prescribed locally.

Prevention consists of early detection of the initial signs of K.’s tumor, 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 sun exposure and contact with oncogenic substances should be avoided.

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

Rice. 1. Structure of the skin of a human finger: 1-5 - epidermis (1 - basal layer, 2 - spinous 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.

Diathesis, manifested in the hereditary tendency of the child’s body to inflammatory processes and allergic reactions. The first signs of such a diathesis may be in the form of a milky scab, persistent diaper rash, the so-called geographic tongue.

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

If the baby is swaddled too tightly, is overheated, does not take care of the skin carefully (especially in the area of ​​the axillary, inguinal-femoral, intergluteal folds), as a result of the irritating effect of skin secretion products (sebum, sweat), as well as urine, feces, the skin turns red, macerates - diaper rash occurs. To prevent the further development of this process, it is necessary to make adjustments to the child’s care system, make sure that he does not overheat, often change underwear, boil, and iron him. An important role is played by careful observance of the toilet of the genital organs and perineum: after each urination and defecation, you should wash the skin 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 the nursing mother (see below). If there are erosions and abrasions in the area, diaper rash easily develops; in this case, the child should be shown to a doctor.

In conditions of improper child care (excessive or insufficient fluid administration), in children who are weakened, suffer from rickets, or have a fever, as a result of an imperfect thermoregulation system and increased sweating, small (pointed) pink nodules and blisters often appear on the skin of the back, back of the neck, and buttocks - prickly heat. In this case, daily hygiene with the addition of chamomile decoction is advisable. After washing, the skin is carefully blotted with soft, carefully ironed diapers or a towel. The child’s skin should be wiped daily with a warm alcohol solution (vodka and half-and-half boiled water). You should also give the child plenty of water, take care of his more comfortable clothing, stop excessive wrapping, use air baths, and avoid using oilcloth or plastic film as linings under the sheet during long sleep, which will help avoid overheating and sweating.

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

Manifestations of allergies on the skin. If a nursing mother violates the diet (consumption of oranges, chocolate, honey, condensed milk, etc.), when introducing complementary foods or switching to artificial feeding, infants may experience manifestations of exudative diathesis in the form of redness of the skin, bright red small nodules, blisters, when opened, weeping areas of skin are formed. After some time, they become covered with yellowish scales and crusts. Most often, such skin changes occur on the face (especially on the cheeks), buttocks, back surface hands, forearms, feet, legs, thighs and are accompanied by itching. These skin changes can develop into childhood eczema and other difficult-to-treat allergic skin diseases. By scratching the affected skin, the child will be able to introduce infectious agents into the lesions, as a result of which the process will worsen. The development of exudative diathesis is facilitated 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 is necessary to take into account that the leading food allergens for children most often can be cow's milk, especially its protein lactoglobulin (boiling milk causes the destruction of lactoglobulin, and the milk becomes less allergenic); chicken eggs, especially whites (heat treatment reduces their allergic properties, but does not completely destroy them); fish, caviar, crayfish, crabs, shrimp and products made 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 and the early introduction of formulas 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 (household, fluff, animal hair), pollen (pollen of herbs, flowering trees). If a child has a reaction to milk, then you can try using it in his diet (kefir, matsoni, biolact, etc.). Acidophilic products prepared by fermenting dairy products, including dry ones, with special acidophilic lactobacilli, which have proteolytic (protein-destroying) and antibacterial properties, are also advisable. Can be entered into more early dates fruit and vegetable purees and beef meat, and cook porridge with fruit and vegetable infusions. Products are often steamed to reduce the content of extractives.

Potatoes, white cabbage, lettuce, peeled cucumbers, green onions, green apple puree, plums, dried fruits, rose hips, beef, cottage cheese. Such children should not be given meat, chicken, fish broth, tomatoes, citrus fruits, cauliflower, green peas, or spinach. In older children, you need to be very careful when introducing chicken, eggs, etc. into the diet. If tolerated well, you can give boiled chicken meat (without skin and chicken broth) once a week. chicken egg, hard-boiled.

Proper nutrition will in many cases prevent the development of chronic allergic diseases. At the same time, it is necessary to provide in the diet that ensures the intake of proteins, fats and carbohydrates, microelements, and vitamins into the body, 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.

The essential components of food are protein products, 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 promote the synthesis of hormones and enzymes. At the same time, easily absorbed fats, which enter the body in large quantities, slow down the synthesis of protective antibodies, increase the susceptibility of tissues to inflammatory reactions, and enhance sensitization processes.

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

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

It is necessary to take into account that the child is largely determined by the nutrition of pregnant women and nursing mothers; it is of great importance in the prevention of allergic diseases in children (infantile eczema, pruritus, neurodermatitis, urticaria, etc.). Pregnant women who themselves or their relatives suffered from any allergic diseases, in order to prevent exudative diathesis and eczema in their unborn child, should exclude eggs, fish, pork, cocoa, chocolate, honey, and pickles from eating during pregnancy and lactation. , canned foods, strawberries, oranges, bananas and other allergenic foods.

To avoid exacerbation of an allergic reaction on the skin when bathing, it is advisable to use boiled water with the addition of decoctions - oak bark, chamomile, string, St. John's wort (until light brown), starch. A hygienic regime is also very important, including walks in the fresh air (at least 2 h daily), preferably in suburban or park areas to avoid contact with air polluting emissions from transport and enterprises. It must be remembered that patients with allergies have increased sensitivity to cooling. It is very important to avoid additional exposure to household allergens (dust, wool, fluff, some types of flowers, etc.), and therefore it is necessary to exclude the patient’s contact with carpets, rugs, animal hair, and aquarium fish food. The apartment must be wet cleaned daily.

Allergic reactions on the skin can occur when treating various diseases with medications ( rice. 1 ), if a state of intolerance to the drug develops, expressed in the appearance of the drug in the form of spots, nodules, bubbles, blisters, as with a nettle burn, on the skin and mucous membranes, accompanied by itching, burning, increased body temperature, and malaise. As first aid, the patient should stop taking the drug and consult a doctor. It is useful to ensure the fastest possible removal of this drug from the body, which is facilitated by drinking plenty of fluids, and for constipation - a laxative. It is also advisable to follow a diet, as with other allergic diseases.

The development of an allergic reaction on the skin can also be caused by contact with varnishes, paints, cement, gasoline, washing powders, glue, plastic and other allergenic substances.

In children, in particular when using plastic chamber pots, redness of the skin of the buttocks in areas of contact with the plastic may occur. In this case, it is necessary to replace the plastic pot with an enamel one or eliminate skin contact with it using flannel pads or another method. Severe inflammatory skin changes ( rice. 2 ) up to the formation of round blisters, increased body temperature, etc. can also occur as a result of contact with certain plants - dandelions, primrose, hogweed. As a first aid measure, it is necessary to wash the skin at the site of contact with boiled water to remove any remaining allergen from the surface of the skin.

Rice. 1. Allergic dermatitis on the cheeks of a boy caused by erythromycin.

Great Medical Encyclopedia

LEATHER- female outer shell, the outer clothing of an animal's body; it is connected to the body by flesh and fiber, covered from the outside with skin, a thin horny layer, and b. husband. wool, feathers, scales, etc. The same shell, removed from an animal, raw or dressed,... ... Dahl's Explanatory Dictionary

Leather- (cutis) is the general cover of the body, the area of ​​which reaches 1.5–2.0 m2. 1 cm2 of skin contains up to 300 sensory nerve endings. In addition to the tactile function, the skin performs a protective function, protecting against damage... ... Atlas of Human Anatomy

- (cutis), the cover of vertebrates, delimits the body from the outside. environment. Performs a number of functions: protective (protects the body from mechanical influences and injuries, penetration of various substances and microorganisms), excretory (excretes... ... Biological encyclopedic dictionary

LEATHER, leather, women's 1. The outer cover of animal (sometimes plant) organisms. The skin was cracked from the cold. All the skin wrinkled. Snakes change their skin. Peel the skin from the apple. 2. Tanned animal skin, freed from wool. Pork suitcase... ... Ushakov's Explanatory Dictionary

Skin. .. to climb out of skin, bones and skin, frost on the skin, frost on the skin... Dictionary of Russian synonyms and expressions similar in meaning. under. ed. N. Abramova, M.: Russian dictionaries, 1999. leather, yukhta, leggings, chevret, shagreen, chevro, husk,... ... Synonym dictionary

SKIN, a durable, elastic covering of the body that performs many functions. Sometimes the skin is considered as an organ of the body. The skin protects the body from damage and from the penetration of microorganisms, and also prevents dehydration. Nerve endings of the skin... ... Scientific and technical encyclopedic dictionary Series:

We present to you Interesting Facts about human skin that you probably didn’t know about.

The skin covers the entire human body and is the largest organ of the human body, possessing diverse functions and closely related to the entire body.

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

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

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

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

• Multilayer weight skin makes up over 11-15 percent of a person’s weight.

Skin function

Its main function is protective.

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

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

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

Epidermis

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

The epidermis or outer layer covers the dermis and is the surface of the skin with ridges and depressions and contains approximately 15 layers. This is the epithelium, constantly created by a layer of basement membrane. The epidermis is divided into 3 layers. The outer or stratum corneum, tough and impervious to water, consists of dead cells that are constantly separated from the epidermal layer in small scales by the action of new cells originating from the inner layers.

The middle layer of the epidermis contains adult (squamous) cells that renew the outer layer, facts about human skin. The middle layer or basement membrane layer creates new cells, which usually develop into squamous cells. The basement membrane layer also contains melanocytes, cells that create the pigment melanin.

Exposure to the sun stimulates the formation of melanin to protect the skin. This is why a tan appears after exposure to the sun. Some fake tanning creams stimulate the formation of melanin, others contain an ingredient (dihydroxyacetone) that gives the skin a red-brown color similar to a tan, fact!

Facts about human skin. Dermis

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

Hypodermis

This layer includes adipose tissue, subcutaneous nerve and vascular channels. The hypodermis also contains hair follicles and sweat glands.
♦ Color of the skin, gender and racial characteristics are possible due to the distribution of four main components on the surface of the skin:
- melanin, a brown pigment - carotene, the color of which varies from yellow to orange
- oxyhemoglobin: red
- carboxyhemoglobin: purple

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

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

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

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

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

♦ Nails and hair also refer to the skin - they are considered its appendages, fact!

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

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

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

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

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

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

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

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

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

• For one sq.cm. The skin contains 30,000,000 different bacteria.

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

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

♦ The skin ages due to UV radiation, stress, lack of sleep, and decreased collagen and fibroblasts.

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

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

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

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

If the body is in water for a long time, the extracellular layer of fat becomes thinner and the water gains access to the skin cells, as a result it swells. Have you seen how the skin of your fingers wrinkles in the water?

This transformation serves to improve traction (just like the treads in car tires).♦Flax skin syndrome

is a rare connective tissue disease in which the skin easily stretches and forms loose folds.

In lax skin syndrome, the elastic fibers are mainly affected. The disease is usually hereditary; in rare cases and for unknown reasons, it develops in people with no precedent in the family.

Some hereditary forms are quite mild, while others are accompanied by some degree of mental retardation. Sometimes the disease leads to death. When sluggish, loose skin

, it easily folds and returns with difficulty to its previous position.
In hereditary forms of the disease, excess skin folds already exist at birth or form later. "Excess" and laxity of skin is especially evident on the face, so that the sick child has a "mournful" appearance. A hooked nose is typical.

In general, lax skin syndrome is a connective tissue pathology. Unthinkable facts about human skin.

Since connective tissue is part of all body systems, the manifestations of the syndrome are very diverse. The osteoarticular, pulmonary, cardiovascular, and digestive systems are affected.

No treatment has been developed. In people with a hereditary form of the disease, reconstructive surgery significantly improves appearance. However, excess skin may form again. Reconstructive surgery is less successful in the case of an acquired form of the disease.
Here are some amazing facts about human skin.

Based on materials from videoplastica.ru, popular-medicine.rf

50 facts about our skin (brief summary)
1. Skin is the largest organ in the human body
2. If you stretch the skin of an average person, it will cover an area of ​​2 square meters
3. Skin makes up about 15 percent of your body weight.

4. There are two types of skin: hairy and hairless
5. Your skin has three layers:
-epidermis - water-repellent and dead layer
-subcutaneous fat - fat and large blood vessels

6. Every inch of your skin has a certain elasticity and strength, depending on its location. So the skin on your knuckles is different from the skin on your stomach.
7. Scar tissue lacks hair and sweat glands
8. The thinnest skin is on your eyelids - about 0.2 mm
9. The thickest skin is on your feet - about 1.4 mm

10. A person has an average of 100,000 hairs on his head. People with blond hair have about 140,000 hairs, dark-haired people have 110,000, and red-haired people have about 90,000.

11. Each hair has a small muscle that lifts the hair in cold and various emotional states
12. Body hair grows from 2 to 6 years
13. We lose between 20 and 100 hairs per day.

14. Keratin forms the outer dead layer of skin and nails
15. More than 50 percent of the dust in the house consists of dead skin.
16. Every 28 days your skin renews itself.
17. Lipids are natural fats that keep the outer layer of skin hydrated and healthy. Detergents and alcohol destroy lipids.

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

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

20. The skin produces about 500 ml of sweat per day.
21. Sweat itself has no odor, and it is thanks to bacteria that body odor appears.
22. Your skin is a microcosm in which more than 1000 species of bacteria and about 1 billion individual bacteria live.
23. The glands that produce earwax are special sweat glands.
24. On average, there are about 14 types of fungi living between your toes.

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

26. People have the same number of melanin cells. Different skin colors are a result of their activity, not quantity.
27. Human skin varies greatly in different parts of the world. According to the well-known classification - the Lushan scale, there are 36 main types of human skin color.
28. 1 in 110,000 people is an albino, meaning they have no melanin cells.
29. Melanin is also responsible for eye color, and the skin covering the eye is transparent and very sensitive.
30. A child’s permanent skin color is formed within about 6 months.

31. The cause of acne or pimples is the excessive production of cells lining the sweat glands.
32. Even kids suffer from acne. Some newborn babies develop acne in the first few weeks of life. The cause of newborn acne is not fully known, but it does not require treatment and goes away on its own.
33. About 80 percent or 4 out of 5 teenagers experience acne.

34. But this is not only a problem of adolescence. One in 20 women and one in 100 men suffer from acne in adulthood
35. The appearance of a boil is associated with staphylococcal bacteria. It penetrates tiny cuts in the skin and enters the hair follicles.

36.The appearance and texture of your skin speaks volumes about your health. When you are sick, your skin turns pale, and when you are tired, bags appear under your eyes.
37. Smoking negatively affects the condition of the skin, depriving it of oxygen and nutrients, slowing blood flow, and also contributing to the appearance of wrinkles.

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

39. Most moles are genetically predetermined even before we are born.
40. People who have more moles on their body live longer and look younger than those who have fewer moles.
41. Almost every person has at least one mole.
42. Moles can appear anywhere, including the genitals, scalp and tongue.
43. Freckles most often appear in people with light color skin.

44. Freckles fade in winter because melanin is not produced in large quantities during the winter months.
45. Freckles can be red, yellow, light brown and dark brown.
46. ​​Unlike moles, freckles do not appear at birth, they appear after a person is exposed to sunlight.

Facts about human skin. What vitamins are needed?

47. Vitamin A heals skin with sun damage and cellulite
48. Vitamin D - reduces rashes and neoplasms
49. Vitamin C - antioxidant, restores vitamin E and protects from the sun
50. Vitamin E is an antioxidant that protects against sun damage and aging.

Skin is the largest human organ covering the body. The complex structure and functions of the skin have developed in the process of human evolution.

What is leather?

Skin is the outer covering, the thickness of which varies in different areas of the skin from 0.5 to 5 mm (not counting the hypodermis). This is an elastic, porous fabric that protects the human body from physical and chemical influences.
Skin has important properties:

• stretching;
• waterproof;
• sensitivity.

The skin is a natural barrier to pathogenic microorganisms. Thanks to temperature, tactile, and pain receptors, the skin reacts to heat and cold, touch, and pain. Hairs grow throughout the body (with the exception of the feet and palms), which protect the skin from overheating and react to external irritants.

The thickest skin is on the palms and soles. The thinnest and softest is on the eyelids and male genital organs.

Internal structure

The skin consists of three layers:

• upper - epidermis or skin;
• middle - dermis or skin itself;
• internal - hypodermis or subcutaneous fat.

Rice. 1. General structure of the skin.

A description of the layers is presented in the table “Structure and functions of the skin”.

Layer	Structure	Functions
Epidermis	Consists of keratinocytes - cells containing keratin (skin protein). The thinnest layer, consisting of five layers: Horny - keratinized cells; Shiny - 3-4 rows of elongated cells; Granular - 2-3 rows of cylindrical, cubic, diamond-shaped cells; spinous - 3-6 rows of spinous keratinocytes; Basal (germinal) - 1 row of young cells. In the basal layer, constant cell division and growth occurs. Melanocytes are also located here - cells that secrete a protective pigment (melanin), and immune cells. Gradually rising (due to the growth of the lower layer), the cells die, are completely filled with keratin and become the stratum corneum, which peels off over time	Mechanical protection; Water repulsion; UV protection due to melanin; Protection against penetration of pathogenic microbes
	The most functional layer. Contains living cells, blood vessels, receptors, sweat glands. Here are the hair follicles from which sensitive hairs grow. Consists of two collagen layers: Papillary - under the epithelium; Reticular - above the hypodermis. Nutrients enter the epidermis layer from the dermis through diffusion.	Giving elasticity to the skin due to the sebaceous glands; Thermoregulation due to the work of sweat glands (they secrete up to 5 liters of sweat to cool the surface of the body); Perception of external stimulus
Hypodermis	The thickest layer. On the skull it is 2 mm, on the buttocks - 10 cm or more. Consists of dense adipose tissue	Thermal insulation; Accumulation of nutrients for skin cells

Rice. 2. The structure of the epidermis.

Hair, nails and skin glands (sweat, sebaceous, milk) are modified human skin and are called skin appendages. Their rudiments are located in the dermis.

Rice. 3. Structure of the dermis.

Metabolism

In addition to providing protection from water, microorganisms, ultraviolet light, as well as thermoregulation and irritation, the skin is involved in metabolic processes.
Some breakdown products are excreted through the skin, in particular:

• urea;
• ammonia;
• salt;
• toxic substances;
• medications.

In addition, the upper layers of the skin are able to absorb oxygen, which accounts for 2% of the body’s total gas exchange.

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The inner layers of the skin synthesize vitamin D under the influence of ultraviolet radiation. Bright skin more susceptible to sunlight than dark ones. However, fair-skinned people, unlike dark-skinned people, are susceptible to sunburn.

What have we learned?

We learned about the structure and functions of human skin. The skin consists of three layers, each of which performs specific functions. The epidermis is a protective layer, the dermis is sensitive, and the hypodermis is insulating.

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The skin plays a very important role in the body. It not only covers the entire body, protecting it from unfavorable conditions, but is also a powerful organ of touch, temperature and pain sensitivity, participates in the thermoregulation of the body, in the release of metabolic products, and in the formation of some biologically important substances.

Skin structure

The structure of the skin is divided into an upper section, the epidermis, and a lower section, the dermis, or the skin itself. On the surface of the dermis there are many dermal papillae in the form of outgrowths, which give the border between the epidermis and dermis a wavy appearance in cross section.

The epidermis protects the skin from adverse effects. It consists of several layers. The lowest layer of epithelial cells adjacent to the dermis is called the basal layer. Its cells constantly multiply, renewing the overlying layers; they also contain the pigment melanin, which determines the color of the skin.

The second layer of epithelium from the bottom is called styloid; its irregularly shaped cells are separated by styloid tubules. The next layer is granular; in the epithelial cells of this layer the process of formation of the horny substance of the skin begins. The fourth layer is shiny, it has this name because of the shine that keratin gives to cells. The topmost layer is the stratum corneum, its cells are flattened, loosely adjacent to each other and constantly slough off.

The dermis, or skin itself, consists of two layers. The lower papillary layer contains connective tissue fibers - elastic, collagen and reticulin. Collagen fibers pass into subcutaneous fat. The top layer of the dermis is called the reticularis. It is dominated by elastic fibers, which give the skin firmness and elasticity. The dermis contains hair follicles, temperature, pain and tactile receptors, sweat and sebaceous glands.

Skin diseases

The condition of the skin affects the health of the entire body as a whole. The condition of the skin suffers when concomitant diseases digestive, endocrine and hematopoietic systems, with insufficient supply of some important substances, in unfavorable environmental conditions.

Skin diseases can occur at any age.

With the congenital genetic disease ichthyosis, excessively dry skin is susceptible to the process of excessive keratinization. It constantly cracks, which causes severe pain.

With dermatitis, inflammation develops in the skin. Contact dermatitis occurs when damaging agents - chemical, physical, biological - are exposed directly to the skin. This type of dermatitis develops at the point of contact, and the affected area is proportional to the area of ​​contact. This category includes dermatitis due to burns by hogweed, upon contact with detergents, etc.

Allergic dermatitis develops upon repeated contact with an allergen, and inflammation is caused by the effects of histamine in the skin. In this case, the reaction is usually disproportionate to the strength of the irritant, and even small amounts of the allergen can cause damage of significant area and intensity. The allergen can either come into direct contact with the skin or come from the digestive tract. Children are characterized by an allergic skin disease called atopic dermatitis. In adulthood, it manifests itself in the form of neurodermatitis. These diseases are characterized by dry skin, flaking, redness and itching.

Hyperkeratosis is manifested by excessive keratinization of the outer layer of the epidermis. This is a non-inflammatory skin disease. Normally, excessive keratinization of the skin occurs during post-traumatic healing. In this case, the upper layers of cells excessively protect the lower layers, which are restored at this time. The phenomena of hyperkeratosis are also detected with prolonged solar irradiation. Symptoms indicating hyperkeratosis are a thick dense layer of keratinized skin, its bumpiness and flaking, painful thickening on the palms and soles, keratinization of hair follicles.

Calluses on the hands and feet during physical work are a special case of hyperkeratosis. They protect the skin from excess pressure. Severe manifestations of calluses can cause flat feet and foot deformities.

Impetigo is more common in children. This is an acute infectious skin disease caused by staphylococci and streptococci. It is highly contagious, especially when the immune system is weakened. Symptoms of impetigo are:

• Focal redness of the skin;
• Small and large blisters with purulent contents in them on a reddened surface;
• Bubbles burst due to damage;
• A golden-yellow crust forms at the site of opening.

The danger of impetigo is that it can spread significantly and lead to inflammatory lesions of other organs and tissues, and subsequently rheumatism.

Skin care

Skin requires regular care. In modern living conditions, she experiences severe stress, and it is important to help her resist adverse environmental factors.

Skin care should begin with general measures that will be beneficial for the entire body as a whole:

• Regular and sufficient sleep;
• Compliance with the work and rest regime;
• Healthy and proper nutrition.

It is important to cleanse the skin daily of sweat and sebaceous secretions, dust, and dead epidermis. A daily shower will help keep it clean, and if you alternate hot and cold water, you will get a workout for the blood vessels, as well as general hardening of the body.

Facial skin care requires a more subtle approach. The skin of the face is thin and delicate, and if not properly cleansed, it can sag and become flabby.

For dry facial skin, it is advisable to wash your face with cool water using cleansers that do not contain soap, which dries the skin very much, washing away the protective lipid layer from it. Movements when washing or cleansing with cosmetic milk should be in the direction of the so-called massage lines. After washing, the skin is toned using special tonics. At night, excessively dry skin is moisturized with cream; it is better to remove excess cream with a cotton swab after 15 - 20 minutes.

At oily skin It is better to use warm water for washing, since hot water increases the secretion of sebum by the glands, and cold water does not sufficiently cleanse the skin. Oily skin needs to be cleansed at least 2 times a day.

For oily skin, it is especially useful to use facial tonics. To regulate the functioning of the sebaceous glands, dermatologists recommend making therapeutic masks for oily skin 1–2 times a week.

A differentiated approach to cleansing and moisturizing the skin will make it beautiful and healthy, prolonging its youth.

Skin is the heaviest organ of the human body, its weight is approximately 16% of body weight (1.5-2.0 sq. m). Impressive, isn't it? At the same time, the layers of skin are very thin.

Skin consists of:

• 50-72% - water
• 25% - protein
• 3% - inorganic salts and fatty acids.

Skin functions:

1. Eliminates waste products from the body, helping the kidneys function.
2. Regulates temperature (summer, winter)
3. Protects the body from environmental influences.
4. Absorbs oxygen through the pores and releases carbon dioxide, the skin helps the lungs in the breathing process.
5. Through the skin, the body absorbs animal and vegetable fats, as well as medicinal substances. When applying cosmetics, we use exactly this function.

Skin layers:

1. Epidermal layer, which is responsible for protective functions.

2. The dermal layer is responsible for the firmness and elasticity of the skin.

3. Subcutaneous fat, which acts as a reserve of nutrients, protects from mechanical stress and preserves the skin of the face.

Layers of the skin: epridermis

This is the thinnest part of the skin layer (no thicker than 2 mm); it consists of 5 layers, the uppermost of which is formed by flat cells. The life cycle of such a cell begins in the very depths of the epidermis in the basal layer and ends in the outer stratum corneum, passing through the spinous and granular layers; this is the metabolism of the skin.

When its functions are not interfered with by aggressive environmental factors, internal diseases, improper use of cosmetics and other negative factors, it is actively updated.

The epidermis of thick skin consists of five layers:

• basal
• spiny
• grainy
• brilliant
• horny.

In thin skin there is no shiny layer.

Epithelial cells of the epidermis (keratinocytes) are continuously formed in the basal layer and are displaced to the overlying layers, undergoing differentiation and ultimately turning into horny scales, exfoliating from the surface of the skin.

Basal layers of skin formed by one row of cubic or prismatic basophilic cells lying on the basement membrane, with well-developed organelles, numerous keratin filaments and tonofilaments. These cells play the role of cambial elements of the epithelium (among them there are stem cells and mitotic figures are found) and provide a strong connection between the epidermis and the dermis (connected with neighboring cells by desmosomes, and with the basal membrane by hemidesmosomes).

Spiky layers of skin consist of several rows of large irregularly shaped cells connected to each other by desmosomes in the area of ​​​​numerous processes (“spines”) that contain bundles of tonofilaments. Organelles are well developed. Dividing cells are found in the deep sections.

Thin granular layers of skin, formed by several rows of flattened (spindle-shaped in section) cells.

Shiny layer of skin(available only in thick skin) - light, homogeneous, contains the protein eleidin. Consists of 1-2 rows of flattened oxyphilic cells with undetectable boundaries. The organelles and nucleus disappear, the keratohyaline granules dissolve, forming a matrix into which the tonofilaments are immersed.

It is formed by flat horny scales that do not contain a nucleus or organelles and are filled with tonofilaments lying in a dense matrix. Their plasmalemma is thickened due to the deposition of proteins (mainly involucrin) on the inner surface. The scales have high mechanical strength and resistance to chemicals. In the outer parts of the layer, desmosomes are destroyed and horny scales are peeled off from the surface of the epithelium.

Regeneration (renewal) of the epidermis ensures its barrier function due to the constant replacement and removal of outer layers that are damaged and contain microorganisms on their surface.

The renewal period is 20-90 days (depending on the area of ​​the body and age), it is sharply reduced when the skin is exposed to irritating factors and in some diseases (for example, psoriasis).

As the cells move towards the surface of the skin, they lose moisture, fill with horny substance - keratin and become flat.

When we lead a healthy lifestyle and take proper care of our skin, the outer layer should be completely renewed in less than a month (28 days).

The skin of the face has a smooth surface and healthy looking. But there are many reasons that complicate this process of skin renewal. For example, the separation of horny scales slows down with age (by one day for each year lived).

• At the age of 18, this process occurs in 28 days, and each year lived adds one day.

For example. If you are 50 years old, this process will take you 60 days (28 days + 32 days). What does it mean? This means that, as a percentage, there are more old cells than young ones. This leads to an increase in the stratum corneum, and, consequently, to skin aging. But the thickness of the stratum corneum is also affected by exposure to sunlight, as this forms a kind of barrier (skin protection) against the rays.

Dermal layers of skin

The dermal layer is located directly below the epidermis. This layer consists of two types of fibers, one of which consists of:

The proteins are collagen and the other is elastin. papillary layer - forms conical protrusions (papillae) protruding into the epidermis, consists of loose fibrous connective tissue with lymphatic and blood capillaries, nerve fibers and endings.

Provides connection between the dermis and the basement membrane of the epidermis with the help of reticular, elastic fibers and special anchor fibrils.

The reticular layer is a deeper, thicker, stronger layer that is formed by dense fibrous unformed connective tissue and contains a three-dimensional network of thick bundles of collagen fibers interacting with a network of elastic fibers.

Subcutaneous tissue (hypodermis) plays the role of a heat insulator, a kind of depot of nutrients, vitamins and hormones, and ensures the mobility of the skin layer. Formed by lobules of adipose tissue with layers of loose fibrous tissue; its thickness is related to our diet and body area, and the general pattern of distribution in the body is determined by the influence of sex hormones.

Any disturbances in this layer, and in particular: with increasing age, breaks in these fibers appear, cellular tone decreases, elasticity is lost, wrinkles form and pores expand, and the elasticity of the skin is lost.

As a figurative and visual example, let’s take a sofa, which is in every home. While it is new, it is elastic, its surface is smooth. Over time, the springs weaken and deformations of the surface of the sofa are already visible, the same thing happens to our skin.

Subcutaneous fat

The deepest layer, subcutaneous fat, consists of connective tissue, the loops of which are filled with fatty lobes.
The thickness of this layer is not the same in different parts of the body; as for the face, this layer is very small here; it is completely absent on the eyelids.

1. Sweat glands are involved in thermoregulation, as well as in the excretion of metabolic products, salts, medicinal substances, heavy metals(increased with renal failure).
2. The sebaceous glands produce a mixture of lipids - sebum, which coats the surface of the skin, softening it and enhancing its barrier and antimicrobial properties.

They are present everywhere in the skin, with the exception of the palms, soles and dorsum of the feet. Usually associated with hair follicles, they finally develop in adolescence during puberty under the influence of androgens (in both sexes). The secretion of the sebaceous glands (20 grams per day) occurs during contraction of the muscle that lifts the hair (formed by smooth muscle cells and passes from the papillary layer of the dermis to the hair follicle). Overproduction of sebum is characteristic of a disease called seborrhea.

One of the skin problems is AGING.

Signs of skin aging are the appearance of barely noticeable wrinkles when the elasticity of the skin is impaired. The skin loses its elasticity and becomes porous. By changing its structure, the skin loses its smoothness, healthy shine and moisture. Slow metabolism gives the face a sallow, dull color; age spots also do not decorate the face.

Causes of skin aging:

1. Decrease in the total number of new cells, cellular energy imbalance.
2. Extending the metabolic cycle of skin cells

All these causes of aging are influenced by internal factors:

• Age
• Wrong lifestyle
• Aggressive (harmful) environmental factors)
• Incorrect use of cosmetics
• Overdue

External factors include:

• Insufficient supply of nutrients and fluids.
• Lack of proper care.
• Environmental pollution, UV radiation
• Intense pace and disrupted natural rhythm of life.

Uncontrollable skin condition factors:

• Heredity
• Age
• Humidity
• Sun exposure
• Temperature
• Wind
• Environmental pollution

Controlled factors:

• Positive attitude
• Healthy lifestyle
• Regular use of products recommended specifically for your skin type.

Scientists have proven that the secret of preserving youth lies in a gene called gandoderm. Ganoderma (lat. Ganoderma lucidum, Reishi or Lingzhi mushroom)) is a genus of tinder fungi from the Ganodermataceae family.

Ganoderma lucidum: a treasure for the skin

It is this higher mushroom that suppresses the work of the gene responsible for aging, stimulating the activity and growth of skin cells, restores the structure of the skin and brings it into ideal condition, and promotes weight loss.

In addition, it is a source of health and beauty of the skin, as it deeply moisturizes it and improves the synthesis of macromolecular proteins that ensure its elasticity.

Thanks to the discovery of epidermal growth factor, the mysteries of aging and biological changes in the body were unraveled.

1. From the age of 21-25, the first shallow wrinkles begin to appear on the face. 75% of women over the age of 36 had fairly deep wrinkles;
2. at the age of 18-40, small pigment spots appear on the face; after 30 years their diameter can exceed 6 mm. 60% of women aged 26-60 years have age spots.

Ganolerma is the first step towards realizing the cherished dream of all humanity - to stop the aging process and restore youth to aging skin.

That's why Ganoderma is called the beauty factor.

Layers of skin

Before directly examining the structure of the skin, we will highlight several important points from the point of view of cosmetic science:

1. The skin consists of layers that differ both in their structure and purpose.
2. The skin is constantly renewed. That is why it can really be improved and rejuvenated.
3. In addition to creating appearance, leather has many important functions, so care must be taken to ensure that decorating efforts do not harm it.
4. The skin is part of the body, so some of its problems simply cannot be solved in isolation.
5. It is a living organ, but some of its structures are more dead than alive. This is the unique structure of the skin and the secret of its endurance.

Whether we are talking about the structure of the skin and its physiology, diseases, appearance, cosmetic care, etc., we should always remember that its main function is to differentiate the internal environment of the body from the external environment.

Layers of the skin: in dermatology, the skin is usually considered to consist of three main layers, each of which is divided into smaller layers:

1. Epidermis

3. Subcutaneous fatty tissue.

a) Histological section of the skin on the inner side of the forearm.

b) Schematic representation of a skin section.

Formally, the stratum corneum of the skin is the uppermost part of the layer called the epidermis.

Layers of the epidermis:

• Horny
• Grainy
• Spiky
• Basal.

But in cosmetology, the stratum corneum is usually considered separately, since this is where the action of most cosmetic products is directed.

- this is the thinnest film on the surface of the skin that can be lifted with a needle and which forms a wall of blisters during a burn. If you put it under a microscope, you can see many translucent scales (horny scales or corneocytes), which are built from a special protein - keratin.

Horny scales were once living cells, but during the development process they lost their nucleus and cellular organelles. From the moment a cell loses its nucleus, it formally becomes dead.

The main job of these dead cells is to protect what is underneath them. In other layers, they perform the same role as the scales of lizards. Except they look less impressive.

Horny scales fit tightly to each other, connected by special outgrowths on the shell. And the entire space between the layers of horny scales is filled with a substance that is a mixture of lipids (fats).

The chemical composition of intercellular lipids is a mixture:

• Ceramides
• Free sphingoid bases
• Glycasilceramides
• Cholesterol
• Cholesterol sulfate
• Fatty acids
• Phospholipids, etc.

This intercellular substance, the layers of skin, performs the same role as cement in brickwork.

Having water-repellent properties, the intercellular substance of the stratum corneum does not allow water and water-soluble substances to enter the skin, as well as prevents excessive loss of water from deep in the skin.

It is thanks to the stratum corneum that the skin is a reliable barrier that protects us from the external environment and foreign substances.

Note that the substances included in cosmetic products are foreign to the skin, since they do not belong to the body. Fulfilling its main task - to protect the body from any external influences, the skin is in no hurry to “recognize the stranger” and tries to prevent cosmetic components from penetrating inside.

Some cosmetics can destroy or weaken the protective layer of the skin, and then it will begin to lose moisture, and its sensitivity to environmental factors will increase.

No matter how strong the scales are and no matter how well the “cement” holds them together, the tests to which the skin is exposed every day are so great that the stratum corneum wears out very quickly (just like clothes wear out).

The way out that nature found from this situation suggests itself - if the clothes are worn out, they need to be changed. Therefore, worn-out horny scales fly off the surface of the skin and turn into ordinary household dust, which accumulates on the lower shelves and under sofas (of course, not only our skin contributes to the formation of dust, but the contribution of the skin is very large).

- this is what we see when we look at the skin, and it is also the main area for the influence of cosmetics. However, its formation begins deep in the epidermis, and it is there that processes occur that affect its appearance.

By acting externally, we can decorate the stratum corneum, improve the properties of the surface (make it smoother and more flexible), and also protect it from damage. And yet, if we want to significantly change its structure, the impact must begin within.

Skin layers: epidermis

The main task of the epidermis is the production of the stratum corneum. The life of the main cells of the epidermis, called keratinocytes, is dedicated to this purpose.

As keratinocytes mature, they move toward the surface of the skin. Moreover, this process is organized so well that the cells move upward in a single layer, “shoulder to shoulder.”

The lowest layer of the epidermis, where continuously dividing cells are located, is called the basal layer. The rate of skin renewal depends on how intensively the cells of the basal layer divide.

Although many cosmetics promise to stimulate cell division in the basal layer, in reality, only a few are able to do this. And this is good, since in some skin conditions stimulation of cell division in the basal layer is undesirable.

The structure of the epidermis. Keratinization.

TO- keratinocyte,
M- melanocyte (pigment cell),
L- Langerhans cell (immune cell),
km- Merkel cell (tactile cell).

On the basement membrane between the basal keratinocytes there are cells responsible for the formation of pigment ( melanocytes).

Slightly higher immune cells responsible for recognizing foreign substances and microorganisms ( Langerhans cells).

Obviously, agents that penetrate deeper than the stratum corneum will affect not only keratinocytes, but also cells of the immune system and pigment cells.

Another type of cell found in the epidermis is Merkel cells - responsible for tactile sensitivity.

Dermis

The dermis is a kind of soft mattress on which the epidermis rests. The dermis is separated from the epidermis by a basement membrane. The dermis contains blood and lymphatic vessels that nourish the skin, while the epidermis is devoid of blood vessels and is completely dependent on the dermis.

The basis of the dermis, like the basis of most mattresses, is made up of “springs”. Only in in this case These are special fibers made from proteins.

Fibers composed of collagen protein ( collagen fibers), are responsible for the elasticity and rigidity of the dermis, and fibers consisting of elastin protein ( elastin fibers), allow the skin to stretch and return to its previous state.

The space between the “springs” is filled with “stuffing”. It is formed by gel-like substances (mainly hyaluronic acid ) that retain water.

Although the dermis is partly protected from external influences by the epidermis and the stratum corneum, it nevertheless gradually accumulates damage. But this happens quite slowly, since all the structures of the dermis are constantly renewed.

If the process of renewal of skin layers went equally well throughout life, then the skin would always remain fresh and youthful. However, as the body ages, all renewal processes in it slow down, which leads to the accumulation of damaged cells, a decrease in the firmness and elasticity of the skin, and the appearance of wrinkles.

Between the fibers are the main cells of the dermis - fibroblasts. Fibroblasts are biosynthetic factories that produce various compounds (components of the intercellular matrix of the dermis, enzymes, signaling molecules, etc.).

The dermis is not visible from the outside. But the condition of its structures determines whether the skin will look elastic or flaccid, whether it will be smooth or wrinkled. Even the color of the skin partly depends on the dermis, since the color of the skin is given by the blood that runs through the vessels of the dermis.

With atrophy of the dermis and epidermis, the skin becomes yellowish due to translucent subcutaneous fat.

Adipose tissue

Adipose tissue, as its name suggests, contains fat. And he should be where he is. Everyone has probably heard the admiring assessment of a slender girl - “she doesn’t have an ounce of fat.” However, if this were true, then the girl would be a pitiful sight.

In fact, there is no beauty without fat, since it is fatty tissue that gives roundness to shapes and gives freshness and smoothness to the skin. In addition, it softens shock, retains heat, and at certain periods of a woman’s life helps in the synthesis of female sex hormones.

Adipose tissue consists of lobules separated by fibrous tissue.

A)— The subcutaneous fatty tissue of an adult is represented by white adipose tissue (picture on the left). In white adipose tissue, mature adipocytes have one large fat droplet (fat vacuole), which can occupy up to 95% of the cell volume.

b)— Adipocytes of brown adipose tissue have many fat vacuoles (picture on the right). Brown adipose tissue is found in newborns and animals. It is believed to play an important role in the body's thermoregulation. There are many blood vessels in adipose tissue, this is necessary for the rapid “release” of fats into the blood or, conversely, for the “capture” of fat from the general circulation.

Inside the lobules there are fat cells, similar to bags of fat, and also blood vessels.

Any disturbances in the quality of adipose tissue - accumulation of excess fat in cells, thickening of the partitions between lobules, swelling, inflammation, etc., have a catastrophic effect on appearance.

Muscular aponeurotic system of skin layers

The facial muscles, strictly speaking, do not belong to the skin. But since they make a significant contribution to age-related changes skin and since cosmetic products have recently appeared that affect them, let’s consider them briefly.

A distinctive feature of the facial muscles is that they are fused into a single muscular-fibrous layer, which is “sewn” to the skin (but not to the bones) in several places.

By contracting, the muscles pull the skin along with them, as a result of which the facial expression changes - the eyebrows frown, the forehead wrinkles, the lips stretch into a smile, etc.

Although such anatomy provides all the richness of human facial expressions, it also creates the prerequisites for wrinkle formation and folds on the skin - firstly, when muscles contract, they constantly stretch the skin, and secondly, due to the fact that the muscular aponeurotic layer is not connected to the bones of the face, the skin sags over the years under the influence of gravity.

Skin vessels

The vascular system of the skin is very complex. But it is necessary to say a few words about it, since many cosmetic products and procedures are aimed at “stimulating blood circulation”, “toning and strengthening skin blood vessels”, etc.

A number of cosmetic defects are of vascular origin, for example, spider veins, stagnant spots after inflammation, “red nose”, etc.

So, the arteries of the skin form a network under the skin, from which branch branches lead into the skin. Directly at the border of the dermis and hypodermis (fat layer), they connect again and form a second network. Vessels that feed the hair follicles and sweat glands depart from it.

All layers of the skin are penetrated by very small vessels, which again often connect with each other, forming networks in each layer of the dermis. Some networks serve power purposes, others work as heat exchange structures.

The peculiarities of blood movement through all these blood labyrinths with numerous transitions between branches are still poorly understood, but there is an opinion that the skin is prone to “starvation” due to the fact that blood can move from arterial vessels to venous ones, bypassing the areas where it should give nutrients and oxygen to cells.

Perhaps the cosmetic effect of facial massage () can be partly explained by the fact that the massage activates the movement of blood, forcing it to run through all the vessels, “without cutting” corners, which prevents a deficiency of blood supply.

The rate of wound healing also depends on the intensity of blood supply. Where blood circulation is impaired for some reason, ulcers that take a long time to heal may form at the site of the wounds.

Based on this, we can conclude that the rate of renewal of the skin layers, very similar to the process of wound healing, will also depend on blood circulation.

The lymphatic system is closely connected with the circulatory system, the vessels of which also form networks and intricate plexuses in the layers of the skin.

Skin vessels carry nutrients into it. At the same time, it is already known that the skin can transform proteins, fats and carbohydrates, destroying them into their component parts with special enzymes and building the necessary structures from the resulting material.

However, does it follow from this that the skin can be “fed” from the outside by spreading oils on it, like on a sandwich? We will talk about this topic separately in another publication, which is being prepared for release by the editors of PhotoElf magazine “ Facial skin care».

An interesting question is whether the skin can remove toxins? In foreign literature one can find statements that the skin, unlike the kidneys and liver, is not an excretory organ, and one should not expect that “toxins” or “waste” will be released through it.

However, there is evidence (“Skin”, ed. A.M. Chernoukh, E.P. Frolov, Medicine, 1982) that the skin can retain and bind toxic metabolites, protecting other organs from their damaging effects, and also remove many metabolic products from the body.

Thanks to its branched vascular network, the skin also participates in gas exchange, releasing carbon dioxide and absorbing oxygen (the skin provides 2% of the body's gas exchange).

Conclusion:

The layers of skin are a collection of living cells(cells of the epidermis, dermis and subcutaneous fat), intercellular substances - products of cell activity (for example, collagen, hyaluronic acid, intercellular lipids of the stratum corneum) and non-living structures (horny scales).

It takes time to affect living cells because living systems change slowly. Rapid change in a living system means either destruction or a state of shock.

However, the structure consisting of non-living elements, that is, the stratum corneum, can be changed. For example, you can saturate it with moisture so that it swells, you can grease it so that it becomes smoother, you can partially exfoliate it, etc. All this will lead to a quick and noticeable change in the appearance of the skin - sometimes in a matter of minutes.

The changes that living structures undergo are harder to notice because they occur over weeks, months, or even years. Therefore, in order to understand what this or that cosmetic product actually does for the skin, its effects must be divided into two groups:

• • Effects on skin cells and
  • Effects on the stratum corneum.

I must say that this is not a very simple task. And yet, it can be solved to a large extent if you know how deeply certain ingredients of cosmetics can penetrate into the layers of the skin, how they will act on its various structures that they encounter along the way, and how certain changes in the inner life skin are reflected in its appearance.

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

Thanks to 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 is adapted to external conditions.

Skin structure

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

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 to protect against mechanical irritants and chemical agents and has 5 layers:

1. basal layer (located deeper than the other layers, also called the germinal layer due to the fact that mitotic division and proliferation of keratinocytes take place in it);
2. stratum spinosum - several rows of polygonal cells, between which there is a space filled with desmoglein;
3. granular layer - consists of cells whose nuclei are filled with keratohyalin granules, an important intermediate product in the production of keratin;
4. shiny layer - located in places where the skin is susceptible to active mechanical influences (on the heels, palms, etc.), serves to protect the deep layers;
5. stratum corneum - contains the protein keratin, which has the ability to bind water, due to which our skin acquires elasticity.

The deep layers of the skin (basal, spinous, granular) have the ability for intensive cell division. New epidermal cells produced regularly replace the upper stratum corneum. The correct process of keratinization and exfoliation of dead epidermal cells is called keratosis.

If keratinization in the skin occurs too intensely, then we are talking about hyperkeratosis. There is also dyskeratosis, or insufficient keratosis, and parakeratosis - improper keratinization and transformation of the upper layer.

The epidermis also contains cells whose function is to prepare the pigment melanin. It is what gives skin and hair color. When exposed to increased amounts of ultraviolet light, melanin production increases (giving the tanning effect). 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 its location on the body). It consists mainly of connective and reticular tissue fibers, which makes our skin resistant to compression and stretching. In addition, the dermis has a well-developed vascular network and a network of nerve endings (due to which we feel cold, heat, pain, touch, etc.).

The dermis consists of two layers:

1. 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. 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, causing the skin to sag (wrinkles appear)

Elastic fibers get their name due to their 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 contain 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 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 appendage structures:

• hair;
• nails;
• sweat glands;
• mammary gland;
• sebaceous glands.

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

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

Sweat glands are layers of the skin that are tubular in shape and located in the dermis and subcutaneous tissue. There are 2 types of sweat glands:

1. eccrine glands - present on the entire surface of the skin and participate in thermoregulation by secreting sweat;
2. 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.

Mammary glands are developed in women and are necessary for milk production.

Skin functions

Human skin has many different functions. We divided them into passive and active.

Skin layers: passive functions:

1. protection from cold, heat, radiation;
2. protection from pressure, impact, friction;
3. protection against chemicals (skin has a slightly acidic pH);
4. protection against germs, bacteria, viruses, fungi (due to the fact that the top layer is constantly peeled off and renewed).

Active functions:

1. fight against pathogenic microbes in the skin (phagocytes, immune system);
2. thermoregulation (sweat production, the nervous and vascular systems of the skin are controlled by signals from the brain, thereby maintaining a constant temperature of the human body);
3. receiving signals from the environment (pain, touch, temperature);
4. recognition of allergens (Langerhans cells, which activate the immune response, are dendritic cells found in the epidermis and dermis);
5. vitamin D production;
6. production of melanin pigment (due to melanocytes);
7. regulation of water and mineral metabolism in the body.