skin functions. Qualification tests in cosmetology which function is not characteristic of human skin
The skin, our outer covering, is one of the most important human organs that performs many functions, including being a sensory organ. The total surface area of our skin is up to 2m2, and its mass is about 5% of the total body weight.
The skin also includes the subcutaneous adipose tissue, the same fat that many successfully or not really struggle with.
The skin produces a special hormone-like substance that mobilizes the body's defenses, as well as vitamin D. Group D vitamins are an indispensable part of the human diet. Long-term vitamin D deficiency can increase the incidence of cancer and increase the likelihood of developing osteoporosis. Without sufficient sun exposure, the body's need for vitamin D cannot be fully met.
The skin has its own closed immune system, two vascular networks and two nerve networks running parallel to the vascular networks.
Our skin is a barrier between the external environment and the human body. The main function of the skin is protective. Skin protects body tissues from damage environment- physical, chemical or biological, softens blows, by increasing pigmentation and thickening the skin protects a person from excessive exposure sun rays, antiseptic environment on the surface of the skin protects the body from penetration pathogenic microbes and so on. The skin also protects the body from hunger, as it is a repository of nutrients, fats, sugars, mineral salts, which, if necessary, can be used by the body. This property of the skin is based on therapeutic starvation.
The lower layer of the skin (hypodermis or subcutaneous fat) and sweat glands provide thermoregulation or, in other words, a constant body temperature (a condition for a constant level of performance by the body of its functions) both in summer and in winter. At an elevated external temperature, the vessels expand, blood flow and heat transfer from the body increase, while at a low temperature, the skin vessels narrow, reducing blood flow and reducing heat transfer. When the body is overheated or tense physical work sweat glands actively secrete sweat - in extreme cases up to ten liters per day. It comes to the surface of the skin and evaporates there. Thus, the skin is cooled and protects the body from overheating.
The skin performs the function of a third lung: about 10% of oxygen enters the body through the skin. Respiratory function skin is very important. If the skin does not breathe, the whole body will suffocate.
The skin maintains the water balance in the body. Millions of sebaceous and sweat glands of the skin provide a partial removal of waste products (slags) from the body.
Our skin is a sense organ, an organ of touch. With the help of sensitive nerve endings in the skin, we feel heat or cold, pain, pressure or vibration. This is possible due to the presence of various nerve receptors in the skin.
Tactile sensitivity is provided by several types of skin mechanoreceptors in the form of free nerve endings, as well as those encapsulated in connective tissue capsules.
One type of free nerve endings are mechanoreceptors that innervate the hair follicles of vellus hair that covers most of our body, as well as coarse hair. They are excited when the hair is moved or twitched. Another type of free nerve endings, mechanoreceptors, is found in the epidermis and in the upper layer of the dermis and reacts to weak stimuli. Apparently, when these receptors are irritated, sensations of tickling or itching occur.
The presence of several varieties of encapsulated receptors makes it possible to receive signals about different properties the same stimulus. Depending on the structure and shape of the capsule, the nerve endings are most susceptible to strong impact either as a result of the perpendicular pressure of the stimulus, or due to the lateral displacement of the capsule.
Most of the encapsulated receptors are found in the hairless skin of the fingers and toes, palms and soles, nipples and genitals, as well as the face, lips and tongue, where they are distributed in varying densities and depths. Skin mechanoreceptors differ in the rate of adaptation to the acting stimulus. Some receptors are excited only at the moment of displacement of the skin or hair and serve as sensors for the speed of exposure to the stimulus. Other receptors do not stop responding to prolonged action of the stimulus if it puts pressure on the skin and serve as sensors for the intensity of the stimulus.
The sensitivity of the skin in different parts of the body is not the same. Even more difference in our perception of touch different sections skin.
An exercise.
Close your eyes. Try to touch an object that is well known to your fingers with an unusual part of the body surface. Most likely, your brain will receive new, unusual information, and this information will be slightly different when touched. different parts body. Digesting this information, the brain receives more "volumetric" knowledge about the subject. By training in this way, you can improve the quality and accuracy of perception, the subtlety of distinguishing different tactile sensations, that is, to improve the quality of this information channel.
Remember the wonderful film by Luc Besson "The Fifth Element"? At the beginning of the film, scientists from a futuristic laboratory were recreating a human body from preserved cells. After recovery bone tissue and muscle scientist says:
Last stage. Irradiation of cells with ultraviolet light stimulates the protective reaction of the body, that is, the skin grows.
Despite the fact that the film belongs to the category of science fiction, the scientist did not lie, and the screenwriters paid Special attention this important process. So what functions does the skin perform and what is its value for the human body? Let's figure it out.
Skin is the result of evolution
So, the structure and functions of the skin, and in general its presence is the result of millions of years of evolution. With the development of new species and populations, the covers changed, improved and adapted to new habitat conditions and environmental factors. According to the theory of evolution, the process of formation of the skin that we have today took place as follows:
- only invertebrates lived in the seas and oceans: sponges and jellyfish, having a single-layer shell (cover);
- the first marine vertebrates, which evolved from sponges and jellyfish, acquired a two-layer shell and were able to produce a protective mucus;
- the first landed vertebrates acquired another layer of integument that produced keratin proteins;
- keratin proteins were transformed into an insulating layer, which appeared in the form of skin.
Vertebrates living on land were exposed to ultraviolet rays (the sun), which played an important role in the evolutionary processes of the appearance of the skin. This was the reference from the movie.
Structure
The skin, like any other organ, is very complex: science articles for several dozen pages. Therefore, let's try to figure it out without the subtleties of scientific topics, in simple and understandable words for everyone.
The skin is made up of three layers: epidermis (upper), dermis (middle), and hypodermis (lower).
The hypodermis is a fatty layer, or, roughly speaking, fat. This is where all the bars and waffles we ate late at night are stored. The thickness of the hypodermis varies in the range (depending on the body part) of 0.2-6 cm, obesity increases these figures by 2-3 times. The hypodermis does a lot of good deeds in the body, and its absence can lead to irreversible consequences, which is especially fraught for women. The main functions of adipose tissue are the regulation of the level of sex hormones and protection internal organs from bruises.
The dermis is what we mean by the skin itself. By the way, the dermis takes most of the nutrient medium and the necessary moisture from fatty tissue and blood, which means that in the pursuit of youth, you should first of all eat right, and not buy expensive cream. The dermis is made up of collagen, elastin and proteoglycan. The first gives the skin elasticity, the second - elasticity, the third retains water.
And finally, the top layer is the epidermis, represented by only a few layers of cells. the main task epidermis is a defense against pathogenic microorganisms. Between the epidermis and the dermis there is a basement membrane, which regulates the exchange processes between the layers and is an additional protective barrier.
Appendages of the epidermis
The upper layer of the skin (epidermis) is supplemented with appendages:
The ability of the epidermis to regenerate
The skin is regenerated (renewed) around the clock. This is possible thanks to keratinocytes - cells that are 80% composed of collagen. Keratinocytes originate in the depths of the epidermis and within 2-4 weeks reach the upper layer of keratinized cells, and then die off. This process is necessary not only for constant renewal, but also to maintain the optimal thickness of the epidermis due to its protective function.
Skin regeneration is of two types:
- physiological - the natural process of renewal of epidermal cells;
- reparative - the healing process as a result of mechanical damage.
Slowdown of regeneration processes
With each year of life, the process of renewal of epidermal cells slows down, which inevitably leads to the first signs of aging - wrinkles. It is generally accepted that main reason Withering of the skin is its insufficient blood supply, as a result of which nutritional deficiencies occur and metabolic processes in cells slow down. By the age of 25, the body begins to redirect the flow of fresh blood to the internal organs, which is why over the next 15-25 years the intensity of skin saturation with nutrients slowly but surely declines. If in a twenty-year-old person the epidermis is renewed in 14-28 days, then in a forty-year-old - in two months.
Functions of the human skin
Imagine a person without skin. What is the risk and what could be the consequences? The pathogenic influence of the surrounding world immediately comes to mind. And this is absolutely true! First of all, human skin performs the function of protection, that is, it provides a kind of barrier from pathogenic bacteria and adverse environmental factors. Including protects internal organs from blows and bruises, which is ensured by the softness and mobility of fatty tissue.
Additional functions skin:
- cleansing - removes from the body harmful products exchange through sweating;
- thermoregulatory - maintains the required temperature of the body by regulating the intensity of sweating and changing the speed of blood flow;
- gas exchange - absorbs oxygen and releases carbon dioxide.
Skin as a sense organ
Touch is our ability to interact with the world around us through tactile sensations. On every millimeter of the skin there are receptors that turn the influence of external stimuli into a nerve impulse. This implies another important function of the skin - receptor, which is represented by:
- sense of touch and pressure;
- feeling cold and warm;
- feeling of pain.
Types of touch:
- active - the sensation of an object with the help of any part of the body (we hold an apple in our hand or walk barefoot on the grass);
- passive - involuntary sensation of the object (the cat lies on our knees);
- instrumental - the sensation of an object with the help of an auxiliary object (inherent in blind people with a cane).
Final summary
So, human skin is the result of the evolution of integuments (from invertebrates to mammals). The skin is made up of three layers: the hypodermis (fatty tissue), the dermis (the actual skin) and the epidermis (surface protection). The epidermis is a layer capable of the regeneration process and having appendages: sweat and sebaceous glands, nails and hair. In the question of what is the main function of the skin, first of all, it is necessary to mention the protective one. Additional functions: gas exchange, cleaning, temperature control. We also do not forget that the skin is a sensory organ that performs a separate function of the skin - a receptor, thanks to which we can feel objects, feel pain and temperature.
, which plays an important role in the life of the body and performs a complex set of physiological functions.
She is actively participates in the process of metabolism, primarily water, mineral, energy, fat, carbohydrate.
The skin is a powerful depot for carbohydrates, for circulating immune complexes, antibodies and antigens, for various other metabolic products, including slags and toxins.
The skin performs a number of important special functions:
Being the outer shell of the body, uniting all organs and systems holistically, the skin performs mechanical protection function due to the strength of collagen and elastic fibers, significant electrical resistance of structures, the presence of elastic subcutaneous fat.
Compact stratum corneum and in single-lipid mantle covering the skin, protecting the skin from drying out.
Water-lipid mantle prevents penetration from outside the microorganisms.
low molecular weight fatty acids contained in it, oppress possible growth of pathogenic flora.
That's why mantle performs the function sterilizer"skin.
elastic subcutaneous tissue helps to protect from external trauma.
Thermoregulatory function of the skin
The thermoregulatory function of the skin is carried out by a variety of mechanisms that maintain a constant body temperature.
Receptor function of the skin
The receptor function of the skin is colossal.
On the one hand, the skin protects the body from many environmental influences, on the other hand, it powerful multivariate analyzer, it is an extensive receptor field.
Receptor field of the skin closely interacts with the central and autonomic nervous systems.
The skin continuously reacts to many irritations coming from the environment, as well as from the internal organs and the central nervous system.
Skin can be imagined screen, on which changes in the activity of various organs and systems of the human body are projected.
secretory function skin
The secretory function of the skin is carried out by activity sweat and sebaceous glands, as well as through keratin formation main protein of the epidermis.
In addition to secretory, the sebaceous glands also carry out an excretory (excretory) function.
With sebum toxic substances are released formed in the intestines, some medicinal substances.
The function of the sebaceous glands is greatly influenced by the endocrine and nervous systems.
Testosterone (male sex hormone) stimulates and estrogens (female sex hormones) inhibit sebum secretion.
Sweat glands largely determine body temperature control.
By producing sweat, they cool the skin, help maintain constant temperature in the body.
With sweat, some medicinal substances are also excreted from the body, incl. antibiotics.
In the regulation of the activity of the sweat glands, the central and autonomic nervous systems play a leading role, while the main stimulator of their activity is an increase in ambient temperature.
Sebaceous and sweat glands, except for the excretion of organic and inorganic products of mineral metabolism removed from the body carbohydrates, hormones, enzymes, trace elements, vitamins and a significant amount of water.
Healthy skin and mucous membranes are immune barrier for microorganisms.
Due to the immunological activity of the main structural parts of the skin, they realize immune response epidermis, dermis and subcutaneous fat.
Respiratory and resorption functions of the skin
The respiratory and resorption functions of the skin depend on the activity of the sebaceous hair follicles, the strength of the stratum corneum, and the state of the water-fat mantle.
In this regard, the surface, for example, the rear of the palms and soles is characterized by a weak suction capacity as a result of physiological hyperkeratosis and the absence of sweat and sebaceous glands.
In places of their abundant location and a weakly expressed, thin stratum corneum, the resorption properties of the skin are well manifested.
Respiratory function of the skin It consists in its absorption of oxygen and the release of carbon dioxide, but it is generally much less significant compared to pulmonary metabolism.
The role of the skin in metabolism, which was mentioned earlier, is especially important because of its great deposition capacity.
Connective tissue cells, argyrophilic, collagen, elastic fibers and subcutaneous adipose tissue have a pronounced hydrophilicity, which causes a delay in intracellular and extracellular fluid, minerals, vitamins and microelements.
The skin stores carbohydrates, amino acids, cholesterol, iodine, bromine, bile acids and slags formed in the process of lipid peroxidation.
In this regard, long before clinical manifestations general metabolic disorders in a particular system or organ, a number of pathological processes, as, for example, the appearance of persistent itching in violation of liver function or persistent pustular elements in the presence of undiagnosed latent diabetes.
In addition to the mentioned functions inherent in the skin, one should also mention the perception of ultraviolet radiation and participation in the metabolism of vitamin D, protection from the damaging effects of sunlight due to the production and content in the cells of melanoblasts and melanocytes of the pigment melanin, which can absorb ultraviolet rays, and, of course, a cosmetic function that is very important for a person's psycho-emotional comfort.
Thus, the functions of the skin are extremely diverse and very important for human life.
Shkiryak-Nizhnik Zoreslav Antonovna, Dr. med. sciences, professor. Head of the Department of Family Health Problems of the Institute of Pediatrics, Obstetrics and Gynecology of the Academy of Medical Sciences of Ukraine, Professor of the Department of Obstetrics, Gynecology and Perinatology of the Kyiv Medical Academy of Postgraduate Education
The skin protects the body from various external influences: physical, chemical and biological. Among the physical effects on the body, the most frequent are mechanical, thermal and light. A variety of mechanical influences - touch, pressure, stretching, blows, injections, cauterization, cooling, and others - depending on the frequency and strength, act favorably on the skin surface in some cases and unfavorably in others. protection from mechanical influences the skin performs due to the presence of a water-fat mantle in it; a special complex in the epidermis; basement membrane; dermis, abundantly saturated with a network of collagen and elastic fibers, as well as subcutaneous adipose tissue (hypoderm). In medical cosmetics, mechanical factors affecting the skin (massage, acupuncture, baths, gymnastics) are widely used.
The protective function of the skin in relation to various chemical factors should be well known to ARGO consultants, especially when applied actively. operating funds such as vitamins, proteins, amino acids, and other chemicals used in skin care. Chemicals are difficult to penetrate through healthy skin, mainly through the hair follicles. The most effective barrier for them is the stratum corneum and the water-fatty mantle. Amino acids on the surface of the stratum corneum protect the skin from acids and bases. But if the protective barrier of the skin is broken, chemical solutions destroy the stratum corneum and water-fatty layer.
The skin well protects the body from the action of biological factors, most often represented by microorganisms. Various microbes getting on the surface healthy skin, cannot develop due to the enzymatic activity of the water-fat membrane rich in fatty acids. Constant renewal of epidermal cells and desquamation of the superficial stratum corneum of the skin leads to mechanical removal microbes on the skin. There is also a normal bacterial flora on the skin, which limits the development of pathogenic bacteria.
Human skin is adapted to prolonged exposure to ultraviolet rays, especially in the inhabitants of sunny regions of the globe. Such exposure, if intense and prolonged, is harmful to health. The skin is the only barrier against such exposure. The horny layer of the epidermis reflects or absorbs the most carcinogenic part of the ultraviolet radiation spectrum (long-wave).
2. Thermoregulatory function.
thermal effect on the skin is characterized by continuous dynamics, and this function is associated with it, thanks to which the body maintains a constant temperature.
Contraction occurs in the cold blood vessels, due to this, heat transfer decreases, and when the ambient temperature rises, the vessels of the skin expand, as a result of which heat transfer increases. Sweat glands are actively connected to this process, the evaporation of the secretion of which leads to "cooling" skin.
3. Excretory function of the skin carried out through the sweat and sebaceous glands.
Sweat secretion. Sweat released to the surface is a solution table salt(sodium chloride). Sweat contains 98-99% water and 1-2% inorganic and organic substances. Among the inorganic substances, in addition to sodium chloride, sweat contains potassium chloride, sulfates, phosphates, traces of iron, zinc, cobalt, tin, magnesium, copper, etc. Organic substances are mainly represented by urea, ammonia, uric acid, amino acids, keratin.
Chemical composition sweat is similar to the composition of urine. It varies depending on the intensity of the kidneys and other factors. Sweat itself is odorless. Typical specific smell appears due to bacterial decomposition of sweat.
Sebaceous secretion. The secret of the sebaceous glands is secreted continuously in an amount proportional to the size of the glands, performing an important function - protecting the skin from wind, cold, sunlight, and pathogens.
The sebaceous glands, together with fat, secrete some toxic substances that are formed in the body as a result of metabolism. In the presence of toxic substances in the intestines, the secretion of the sebaceous glands increases. Therefore, in the treatment of seborrhea, substances are prescribed inside that adsorb intestinal toxins.
Age and gender factors affect the secretion of the sebaceous glands: in childhood it is insignificant; in adulthood increases, especially in men; weakens with age, especially in women. After 40 years of life, the production of sebum is noticeably reduced, but if you thoroughly wash your skin with soap or wipe it with alcohol, the activity of the sebaceous glands will increase and the fatty film of the skin will be restored in 3-4 hours.
4. The skin performs respiratory and gas exchange functions in the body along with the lungs. The skin is certainly permeable to gases (oxygen, carbon dioxide, hydrogen sulfide) and volatile liquids (chloroform, ether, alcohol). Through it, oxygen is absorbed from the air, carbon dioxide is released.
5. Huge role of the skin as a sense organ.
There are tactile, pain, heat and cold skin sensitivity.
Different kinds skin sensitivity distributed unevenly over the surface. The tips of the fingers, the red border of the lips, the tip of the tongue have the greatest tactile sensitivity; temperature sensitivity is more pronounced on the skin of the face.
6. exchange function skin
Being the second largest after the muscles, the depot of water introduced into the body, the skin participates in the body's water metabolism, in addition, deposits (deposits) sodium chloride (salt metabolism), and is also one of the links in vitamin, nitrogen and carbohydrate metabolism.
The skin is very sensitive to all changes occurring in the body. A number of diseases of the internal organs and endocrine glands dramatically affect the condition of the skin, causing various changes in it.
A beautiful clear complexion, an even blush almost always indicate good health; on the contrary, pallor, yellowness of the skin often indicate anemia, cardiovascular insufficiency, diseases of the liver, lungs, dysfunction of the endocrine glands and other pathologies.
7. Protective (immune) function.
In addition to the above, the skin plays an important role in the development defensive forces organism.
So, the skin reflects the state of our body. This is not a shell, but an organ with a multifaceted, complex activity associated with the work of all human organs and systems.
The skin performs a number of vital important functions and interacts with all human organs. Due to the influence of adverse factors, a failure in the implementation of a particular function may occur. In the future, this will inevitably lead to skin problems. To prevent this from happening, cosmetics and facial treatments should be selected taking into account all the properties of the skin.
Protective function of the skin. This is perhaps the main function of the skin. First of all, it means the protection of internal organs from mechanical influences. This is due to the regenerating properties of the epidermis, the elasticity and strength of the fibers of the dermis and, of course, due to the subcutaneous adipose tissue.
The skin also protects the human body from excessive ultraviolet radiation. It is known that not only leads to premature aging skin, but can also cause precancerous conditions and even skin cancer. The main blow is taken by the stratum corneum, which partially blocks ultraviolet rays.
Another means of protection against radiation is sunburn. The process of its formation is due to the development coloring pigment- melanin - in the deepest layer of the epidermis. This pigment is a kind of light filter that absorbs light waves of various ranges and protects cells from the damaging effects of ultraviolet radiation.
The bactericidal property of the skin is ensured by the hydrolipidic film on the surface of the skin, as well as the special acid composition of sweat and secretions of the sebaceous glands.
The protective function of the skin weakens as a result of a decrease in immunity, due to illness, overwork, pollution, and hypothermia. As a consequence, this leads to inflammatory diseases skin.
The regenerating function of the skin. Often, by the word "skin" we mean only its dead part, or the so-called stratum corneum. It consists of keratinized dead cells. They, before getting to the surface of the skin, go a long way, equal in time to about one month. Young cells form in the germinal layer of the epidermis and gradually move upward, losing their nucleus and becoming flatter. The layer of skin that we see is already formed by completely dry non-nuclear cells.
Every day in the process of washing, wiping, we lose up to 2 billion cells! However, they are immediately replaced by others - this is regeneration. Ideally this process should be completed in a timely manner and without interruption. In practice, many of us quite often encounter such a phenomenon as peeling. This indicates a violation of the established mechanism of regeneration. In this case, exfoliators come to the rescue. cosmetic procedures. The regenerating function also underlies the removal of freckles and the removal of birthmarks.
Thermoregulatory function of the skin. The skin protects the human body from overheating and hypothermia and helps maintain body temperature at a constant level (about 37 ° C). Thermoregulation is closely related to the functioning of the nervous system. The skin perceives temperature fluctuations due to the nerve endings located in it. The sensitivity of different parts of the body is not the same. So, the skin on the face reacts less to temperature changes. But the skin of the extremities is the most sensitive. On average, the skin reacts to a temperature difference of only 0.5 °C.
The mechanism of thermoregulation is based on irritation of the nerves, which leads to a change in the state of the vessels. So, when the skin is exposed to cold, the vessels narrow, thereby preventing heat from leaving the body. But the heat, on the contrary, leads to the expansion of blood vessels and an increase in heat transfer.
❧ To preserve the beauty and health of the skin, you should adhere to a reasonable diet, alternate work and rest modes, and of course follow the rules daily care for her.
❧ The acidity index of any cosmetic should match your own. For oily skin it is equal to three, for dry - four. But even if the skin does not have imperfections, its pH can vary depending on the area of the face within 4-6 units.
An important role in heat exchange is played by sweat glands. The release of sweat and its further evaporation helps to lower body temperature. Conversely, as the air temperature decreases, heat transfer decreases.
The metabolic function of the skin. The skin is involved in many metabolic processes of the body, so this function includes several aspects. The skin is involved in gas exchange. Of course, its role in this process is not as great as that of the lungs, but nevertheless, 2% of general allocation carbon dioxide by the body passes through the skin. As for water vapor, the skin emits twice as much of it as the lungs. In addition to oxygen and carbon dioxide, ammonia and hydrogen sulfide penetrate the human body through the skin. This property is based on the principle of action of some medical and preventive procedures, such as therapeutic baths.
The skin is directly involved in water-salt, protein, fat and carbohydrate metabolism. Fats and substances soluble in them through the stratum corneum and hair channels are able to penetrate deep into the skin.
This feature is based on the action of various cosmetics, which contain vitamins, healing substances, vegetable and animal fats.
Occur in the skin chemical processes important for the whole organism. It is in it that under the action of sunlight most of the vitamin D is formed. It is necessary for phosphorus and calcium metabolism.
Enzymes are also synthesized in the skin - substances that activate certain hormones. For example, they convert the hormone cortisone into the more powerful hydrocortisone. Another important aspect This function is the ability of the skin to cleanse. Through the sebaceous and sweat glands, along with their secretions, metabolic products are released that accumulate in the blood and tissues and are harmful to our body (urea, ammonia, etc.). The skin removes harmful chemical substances that we consume with water, food and medicines.
