The most familiar and most incredible substance on Earth is water. The importance of water cannot be overestimated in the life of all living things on the planet; it is present in every moment of our existence. Being the predominant element in the composition of any organism, water also controls its life activity.

Water in nature

Throughout its existence, humanity has been trying to unravel the mystery of this amazing and contradictory element. How did it arise, how did it get to our planet? Probably no one will be able to answer this question, but everyone knows that the importance of water in nature and human life is unimaginably great. One thing is absolutely true - today there are as many water reserves on Earth as there were at the birth of the universe.

The unique properties of water to contract when heated and expand when frozen is another reason to be surprised. No other substance has similar properties. And its ability to move from one state to another, so familiar and at the same time amazing, playing an exceptional role, makes it possible for all living organisms to exist on Earth. The Higher Mind has assigned water the main role in maintaining life and participating in constantly occurring natural processes.

The water cycle

This process is called the hydrological cycle, which is a continuous circulation of water from the hydrosphere and the surface of the earth into the atmosphere, and then back. There are four processes involved in the cycle:

• evaporation;
• condensation;
• precipitation;
• water flow

Once on the ground, part of the precipitation evaporates and condenses, another part, thanks to runoff, fills reservoirs, and the third turns into going underground. So, constantly moving, feeding waterways, plants and animals and preserving its own reserves, water wanders, protecting the Earth. The importance of water is obvious and indisputable.

The mechanism of the cycle and its types

In nature there is a large cycle (the so-called global cycle), as well as two small ones - continental and oceanic. Precipitation collected over the oceans is carried by winds and falls on the continents, and then returns to the ocean with runoff. The process where ocean water continuously evaporates, condenses and falls back into the ocean is called the small ocean gyre. And all similar processes occurring over land are combined into a small continental cycle, in which water is the main character. Its importance in the natural processes of continuous circulation that maintains the Earth’s water balance and ensures the existence of living organisms is indisputable.

Water and man

Having no nutritional value in the usual sense, water is the main component of any living organism, including humans. No one can exist without water. Two-thirds of any organism is water. The importance of water is extremely important for the proper functioning of all systems and organs.

Throughout life, a person comes into contact with water every day, using it for drinking and food, hygiene procedures, recreation and heating. Not found on Earth
a more valuable natural material, as vital and irreplaceable as water. Going without food for quite long periods of time, a person will not live without water for even 8 days, since within 8% of body weight a person begins to faint, 10% causes hallucinations, and 20% inevitably causes death.

Why is water so important to humans? It turns out that water regulates all basic life processes:

• normalizes oxygen humidity, increasing its absorption;
• carries out thermoregulation of the body;
• dissolves nutrients, helping the body absorb them;
• moisturizes and creates protection for vital organs;
• forms a protective lubricant for joints;
• improves metabolic processes in the functioning of body systems;
• promotes the evacuation of waste from the body.

How to stay hydrated

On average, a person loses 2-3 liters of water per day. In more extreme conditions, such as heat, high humidity and physical activity, water loss increases. To maintain the normal physiological water balance of the body, it is necessary to balance the intake of water with its removal through proper

Let's do some calculations. Considering that a person’s daily need for water is 30-40 grams per 1 kg of body weight and about 40% of the total need comes from food, the rest should be taken in the form of drinks. In summer, daily water consumption corresponds to 2-2.5 liters. The hot regions of the planet dictate their requirements - 3.5-5.0 liters, and in extremely hot conditions up to 6.0-6.5 liters of water. The body must not be dehydrated. Alarming symptoms of this problem are dry skin accompanied by itching, fatigue, a sharp decrease in concentration, blood pressure, headaches and general malaise.

Beneficial effect

It is interesting that, by being directly involved in metabolic processes, water promotes weight loss. There is a common misconception that people who want to lose weight need to drink less water, since the body retains water, causes significant harm. You cannot drive your body into even greater stress by knocking it out of its usual water exchange. In addition, moisture, being a natural diuretic, tones the kidneys, causing weight loss.

By receiving the optimal amount of water, a person gains strength, energy and endurance. It is easier for him to control his weight, since even the psychological inconvenience of forced changes when reducing his usual diet is easier to bear. Scientific research has proven that daily consumption of sufficient amounts of clean water helps fight serious illnesses - helps relieve back pain, migraines, reduce blood sugar and cholesterol levels and blood pressure. In addition, by toning the kidneys, water inhibits the formation of stones. It has been proven that people with a creative streak tend to drink a lot, and great artists were pushed to create masterpieces. The importance of water, it turns out, is also important in art.

Plant water exchange

Just like humans, any plant needs water. In different plants it makes up from 70 to 95% of the mass, controlling all ongoing processes. Metabolism in a plant is possible only with a large amount of moisture, so the importance of water for plants is undoubtedly great. By dissolving minerals in the soil, water delivers them to the plant, ensuring their continuous flow. Without water, seeds will not germinate, and the process of photosynthesis will not occur in green leaves. Filling water ensures its viability and preservation of a certain shape.

The most important condition for the life support of a plant organism is the ability to absorb water from the outside. The plant, receiving water mainly from the soil with the help of its roots, delivers it to the above-ground parts of the plant, where the leaves evaporate it. Such water exchange exists in every organic system - water, entering it, evaporates or is released, and then again, enriched with useful substances, enters the body.

Another amazing way water penetrates living cells is its osmotic absorption, i.e. the ability of water to accumulate from outside into cellular solutions, increasing the volume of fluid in the cell.

The art of water consumption

Constant consumption of clean water significantly improves the mental activity of the brain and coordination of movement, and therefore, the importance of water for the life of brain cells is especially valuable. That's why healthy man You shouldn’t limit yourself to drinking, but you should follow some rules:

• drink little but often;
• You should not drink a lot of water at once, as an excess of fluid in the blood will put unnecessary stress on the heart and kidneys.

So, the importance of water for living organisms is enormous. Therefore, creating conditions for maintaining one’s own water balance is necessary for every person.

Water– the most important factor in the formation of the internal environment of the body and at the same time one of the factors of the external environment. Where there is no water, there is no life. All processes characteristic of living organisms inhabiting our Earth occur in water. Lack of water (dehydration) leads to disruption of all body functions and even death. Reducing the amount of water by 10% causes irreversible changes. Tissue metabolism and vital processes take place in an aquatic environment.

Water participates in the processes of assimilation and dissimilation, in the processes of resorption and diffusion, sorption and desorption, and regulates the nature of osmotic relationships in tissues and cells. Water regulates acid-base balance and maintains pH. Buffer systems are only active in conditions where there is water.

Water is a general indicator of the activity of physiological systems, the background and environment in which all vital processes take place. It is no coincidence that in the human body the water content approaches 60% of the total body weight. It has been established that the aging process is associated with the loss of water by cells.

It should be noted that hydrolysis reactions, as well as all redox reactions, occur actively only in aqueous solutions.

Water takes an active part in the so-called water-salt exchange. The processes of digestion and respiration proceed normally if there is enough water in the body. The role of water in the excretory function of the body is also great, which contributes to the normal functioning of the genitourinary system.

The role of water is also great in the processes of thermoregulation of the body. It is involved, in particular, in one of the most important processes - the process of sweating.

It should be noted that minerals enter the body with water, and in a form where they are absorbed almost completely. The role of water as a source of mineral salts is now generally recognized. This is the so-called pharmacological value of water. And Mineral salts in water are in the form of ions, which is favorable for their absorption by the body. Macro- and microelements in food products are in the form of complex compounds, which, even under the influence of gastrointestinal juice, are poorly dissociated and therefore less easily absorbed.

Water is a universal solvent. It dissolves all physiologically active substances. Water is a liquid phase that has a certain physical and chemical structure, which determines its ability as a solvent. Living organisms that consume water with different structures develop and grow differently. Therefore, the structure of water can be considered as the most important biological factor. The structure of water can change during desalination. The structure of water is greatly influenced by the ionic composition of water.

A water molecule is not a neutral compound, but an electrically active one. It has two active electrical centers that create an electric field around itself.

The structure of the water molecule is characterized by two features:

1) high polarity;

2) a peculiar arrangement of atoms in space.

According to modern concepts, a water molecule is a dipole, i.e. it has 2 centers of gravity. One is the center of gravity of positive charges, the other is the center of gravity of negative charges. In space, these centers do not coincide, they are asymmetrical, that is, a water molecule has two poles that create a force field around the molecule, the water molecule is polar.

In an electrostatic field, the spatial arrangement of water molecules (water structure) determines the biological properties of water in the body.

Water molecules can exist in the following forms:

1) in the form of a single water molecule - it is a monohydrol, or simply a hydrol (H 2 O) 1;

2) in the form of a double water molecule - it is a dihydrol (H 2 O) 2;

3) in the form of a triple water molecule - trihydrol (H 2 O) 3.

The aggregate state of water depends on the presence of these forms. Ice usually consists of trihydrols, which have the largest volume. The vapor state of water is represented by monohydrols, since significant thermal movement of molecules at a temperature of 100 °C disrupts their association. In the liquid state, water is a mixture of hydrol, dihydrol and trihydrol. The relationship between them is determined by temperature. The formation of di- and trihydrols occurs due to the attraction of water molecules (hydrols) to each other.

Depending on the dynamic balance between forms, certain types of water are distinguished.

1. Water associated with living tissues is structural (ice-like, or perfect, water), represented by quasicrystals and trihydrols. This water has high biological activity. Its freezing point is –20 °C. The body receives such water only from natural products.

2. Freshly melted water is 70% ice-like water. It has medicinal properties, helps to increase adaptogenic properties, but quickly (after 12 hours) loses its biological properties to stimulate biochemical reactions in the body.

3. Free, or ordinary, water. Its freezing point is 0 °C.

Dehydration

1) with air through the lungs (1 m 3 of air contains on average 8-9 g of water);

2) through the kidneys and skin.

In general, a person loses up to 4 liters of water per day. Natural water losses must be compensated by introducing a certain amount of water from outside. If the losses are not equivalent to the administration, dehydration occurs in the body. A lack of even 10% of water can significantly worsen the condition, and an increase in the degree of dehydration to 20% can lead to impairment of vital functions and death. Dehydration is more dangerous to the body than starvation. A person can live without food for 1 month, and without water - up to 3 days.

Regulation of water metabolism is carried out using the central nervous system (CNS) and is under the control of the food center and thirst center.

The origin of the feeling of thirst is apparently based on a change in the physicochemical composition of the blood and tissues, in which disturbances in osmotic pressure occur due to their depletion of water, which leads to excitation of parts of the central nervous system.

An important role in the regulation of water metabolism is played by the endocrine glands, especially the pituitary gland. The relationship between water and salt metabolism is called water-salt metabolism.

Water consumption standards are determined:

1) water quality;

2) the nature of the water supply;

3) the state of the body;

4) the nature of the environment, and primarily the temperature and humidity conditions;

5) the nature of the work.

Water consumption standards are made up of the physiological needs of the body (2.5-5 liters per day for physiological functions) to maintain life and water necessary for household and communal purposes. The latest standards reflect the sanitary level of the locality.

In a dry and hot climate, when performing intense physical work, physiological norms increase to 8-10 liters per day, in rural areas (with decentralized water supply) - up to 30-40 liters. Water consumption standards at an industrial enterprise depend on the production ambient temperature. They are especially great in hot shops. If the amount of heat generated is 20 kcal per 1 m 3 per hour, then the water consumption standards per shift will be 45 liters (including showering). According to sanitary standards, water consumption standards are regulated as follows:

1) in the presence of running water and no baths - 125-160 liters per day per person;

2) in the presence of running water and baths - 160-250 l;

3) in the presence of running water, baths, hot water– 250-350 l;

4) under conditions of using water dispensers -30-50 l.

Today, in large modern cities, water consumption per capita per day is 450 liters or more. Thus, in Moscow the highest level of water consumption is up to 700 liters. In London - 170 l, Paris - 160 l, Brussels - 85 l.

Water is a social factor. Social living conditions and the level of morbidity depend on the quantity and quality of water. According to WHO, up to 500 million diseases per year that occur on Earth are associated with water quality and water consumption levels.

Factors that shape water quality can be divided into 3 large groups:

1) factors determining the organoleptic properties of water;

2) factors determining the chemical properties of water;

3) factors determining the epidemiological danger of water.

Factors determining the organoleptic properties of water

The organoleptic properties of water are formed by natural and anthropogenic factors. Odor, taste, color and turbidity are important quality characteristics drinking water. The reasons for the appearance of odors, tastes, color and turbidity in water are very diverse. For surface sources, these are primarily soil pollution coming with the flow of atmospheric water. The smell and taste may be associated with algal blooms and subsequent decomposition of vegetation at the bottom of the reservoir. The taste of water is determined by its chemical composition, the ratio of individual components and the amount of these components in absolute values. This especially applies to highly mineralized groundwater due to the increased content of sodium chlorides, sulfates, and, less commonly, calcium and magnesium. Thus, sodium chloride causes the salty taste of water, calcium – astringent, and magnesium – bitter. The taste of water is also determined by the gas composition: 1/3 of the total gas composition is oxygen, 2/3 is nitrogen. There is a very small amount of carbon dioxide in water, but its role is great. Carbon dioxide can be present in water in various forms:

1) dissolved in water to form carbonic acid CO 2 + H 2 O = H 2 CO 3 ;

2) dissociated carbonic acid H 2 CO 3 = H + HCO 3 = 2H + CO 3 with the formation of bicarbonate ion HCO 3 and CO 3 – carbonate ion.

This balance between different forms of carbon dioxide is determined by pH. In an acidic environment, at pH = 4, free carbon dioxide is present - CO 2. At pH = 7-8, the HCO 3 ion is present (moderately alkaline). At pH = 10, the CO 3 ion is present (alkaline environment). All these components determine the taste of water to varying degrees.

For surface sources, the main cause of odors, tastes, color and turbidity is soil pollution coming from atmospheric water runoff. An unpleasant taste of water is typical for widespread highly mineralized waters (especially in the south and southeast of the country), mainly due to the increased concentration of sodium chlorides and sulfates, and less often calcium and magnesium.

The color (color) of natural waters often depends on the presence of humic substances of soil, plant and planktonic origin. The construction of large reservoirs with active processes of plankton development contributes to the appearance of unpleasant odors, tastes and colors in the water. Humic substances are harmless to humans, but they worsen the organoleptic properties of water. They are difficult to remove from water, and they also have a high sorption capacity.

The connection between population morbidity and the nature of water consumption has long been noted. Already in ancient times, some signs of water hazardous to health were known. However, only in the middle of the 19th century. Epidemiological observations and bacteriological discoveries by Pasteur and Koch made it possible to establish that water may contain some pathogenic microorganisms and contribute to the emergence and spread of diseases among the population. Among the factors determining the occurrence of waterborne infections are:

1) anthropogenic water pollution (priority in pollution);

2) release of the pathogen from the body and entry into the body of water;

3) stability of bacteria and viruses in the aquatic environment;

4) entry of microorganisms and viruses with water into the human body.

Waterborne infections

Waterborne infections are characterized by:

1) a sudden rise in incidence;

2) maintaining a high level of morbidity;

3) a rapid decline in the epidemic wave (after eliminating the pathological factor).

Cholera, typhoid fever, paratyphoid fever, dysentery, leptospirosis, tularemia (contamination of drinking water with rodent secretions), and brucellosis are transmitted by water. The possibility of the water factor in the transmission of Salmonella infections cannot be ruled out. Viral diseases include intestinal viruses and enteroviruses. They enter the water with fecal matter and other human secretions. In the aquatic environment you can find:

1) infectious hepatitis virus;

2) polio virus;

3) adenoviruses;

4) Coxsackie virus;

5) basin conjunctivitis virus;

6) influenza virus;

7) ECHO virus.

Amoebiasis. Dysenteric amoeba, common in the tropics and Central Asia, is of pathogenic importance. Vegetative forms of amoeba die quickly, but the cysts are resistant to water. Moreover, chlorination at usual doses is ineffective against amoeba cysts.

Helminth eggs and Giardia cysts enter water bodies with human secretions, and enter the body through drinking or contaminated water.

It is generally accepted that the possibility of eliminating the danger of water epidemics and thereby reducing the incidence of intestinal infections in the population is associated with progress in the field of water supply to the population. Therefore, properly organized water supply is not only an important general sanitary measure, but also an effective specific measure against the spread of intestinal infections among the population. Thus, the successful elimination of the Eltor cholera outbreak in the USSR (1970) was largely due to the fact that the majority of the urban population was protected from the danger of its spread by water thanks to a normal centralized water supply.

Chemical composition of water

Factors that determine the chemical composition of water are chemical substances that can be divided into:

1) bioelements (iodine, fluorine, zinc, copper, cobalt);

2) chemical elements, harmful to health (lead, mercury, selenium, arsenic, nitrates, uranium, surfactants, toxic chemicals, radioactive substances, carcinogenic substances);

3) indifferent or even useful chemicals (calcium, magnesium, manganese, iron, carbonates, bicarbonates, chlorides).

The chemical composition of water is possible reason diseases of non-infectious nature. We will analyze the basics of standardization of indicators of the harmlessness of the chemical composition of drinking water below.

Indifferent chemicals in water

Iron divalent or trivalent is found in all natural water sources. Iron is a necessary component of animal organisms. It is used to build vital respiratory and oxidative enzymes (hemoglobin, catalase). An adult receives tens of milligrams of iron per day, so the amount of iron supplied with water has no significant physiological significance. However, the presence of iron in the form of large concentrations is undesirable for aesthetic and everyday reasons. Iron gives water turbidity, a yellow-brown color, a bitter metallic taste, and leaves rust stains. A large number of Iron in water promotes the development of iron bacteria, which, when they die, accumulate dense sediment inside the pipes. Bivalent iron is more often found in groundwater. If water is pumped, then, combining on the surface with oxygen in the air, iron becomes trivalent, and the water becomes brown. Thus, the iron content in drinking water is limited by its effect on turbidity and color. The permissible concentration according to the standard is no more than 0.3 mg/l, for underground sources no more than 1.0 mg/l.

Manganese in groundwater it is contained in the form of bicarbonates, highly soluble in water. In the presence of atmospheric oxygen, it turns into manganese hydroxide and precipitates, which increases the color and turbidity of the water. In the practice of centralized water supply, the need to limit the manganese content in drinking water is associated with a deterioration in organoleptic properties. The norm is no more than 0.1 mg/l.

Aluminum found in drinking water that has been treated - clarified during the coagulation process with aluminum sulfate. Excessive concentrations of aluminum give water an unpleasant, astringent taste. The residual aluminum content in drinking water (no more than 0.2 mg per liter) does not cause a deterioration in the organoleptic properties of water (turbidity and taste).

Calcium and its salts cause water hardness. The hardness of drinking water is an essential criterion by which the population evaluates the quality of water. In hard water, vegetables and meat are poorly cooked, since calcium salts and food proteins form insoluble compounds that are poorly absorbed. Washing clothes is difficult; scale (insoluble sediment) forms in heating appliances. Experimental studies have shown that when drinking water with a hardness of 20 mg. eq/l, the frequency and weight of stone formation were significantly greater than when drinking water with a hardness of 10 mg. eq/l Effect of water with a hardness of 7 mg. eq per l on the development of urolithiasis was not detected. All this allows us to consider the accepted standard for hardness in drinking water – 7 mg eq per liter – justified.

Bioelements

Copper It is found in small concentrations in natural groundwater and is a true biomicroelement. The need for it (mainly for hematopoiesis) of an adult is small - 2-3 g per day. It is covered mainly by the daily food ration. In high concentrations (3-5 mg/l), copper affects the taste (astringent). The standard for this criterion is no more than 1 mg/l. in water.

Zinc It is found as a trace element in natural ground waters. It is found in high concentrations in water bodies polluted by industrial wastewater. Chronic zinc poisoning is unknown. Zinc salts in high concentrations are irritating to the gastrointestinal tract, but the importance of zinc compounds in water is determined by their effect on organoleptic properties. At 30 mg/l, water acquires a milky color, and the unpleasant metallic taste disappears at 3 mg/l, so the zinc content in water is normalized to no more than 3 mg/l.

The chemical composition of water as a cause of non-infectious diseases

The development of medical science has made it possible to expand our understanding of the characteristics of the chemical (salt and microelement) composition of water, its biological role and possible harmful effects on public health.

Mineral salts (macro- and microelements) take part in mineral metabolism and the vital functions of the body, affect the growth and development of the body, hematopoiesis, reproduction, and are part of enzymes, hormones and vitamins. Iodine, fluorine, copper, zinc, bromine, manganese, aluminum, chromium, nickel, cobalt, lead, mercury, etc. are found in the human body.

In nature, microelements are constantly dissipated (due to meteorological factors, water, and the vital activity of organisms). This leads to their uneven distribution (lack or excess) in the soil and water of different geographical regions, which leads to changes in flora and fauna and the emergence of biogeochemical provinces.

Among the diseases associated with the unfavorable chemical composition of water, endemic goiter is primarily isolated. This disease is widespread in the area Russian Federation. The causes of the disease are absolute iodine deficiency in the external environment and the social and hygienic living conditions of the population. The daily requirement for iodine is 120-125 mcg. In areas where this disease is not typical, iodine enters the body from plant foods (70 mcg of iodine), from animal food (40 mcg), from air (5 mcg) and from water (5 mcg). Iodine in drinking water plays the role of an indicator of the general level of this element in the external environment. Goiter is common in rural areas, where the population eats exclusively locally sourced foods and there is little iodine in the soil. Residents of Moscow and St. Petersburg also use water with a low iodine content (2 mcg), but there are no epidemics here, since the population eats imported products from other regions, which ensures a favorable iodine balance.

The main preventive measures against endemic goiter are balanced diet, salt iodization, adding copper, manganese, cobalt, iodine to the diet. Carbohydrate foods and plant proteins should also predominate, as they normalize the function of the thyroid gland.

Endemic fluorosis is a disease that appears in the indigenous population of certain regions of Russia, Ukraine and others, early symptom which is damage to the teeth in the form of enamel spotting. It is generally accepted that spotting is not a consequence of topical fluoride. Fluoride, entering the blood, has a general tactical effect, primarily causing the destruction of dentin.

Drinking water is the main source of fluoride in the body, which determines the decisive role of fluoride in drinking water in the development of endemic fluorosis. The daily diet provides 0.8 mg of fluoride, and the fluoride content in drinking water is often 2-3 mg/l. There is a clear connection between the severity of enamel damage and the amount of fluoride in drinking water. A previous infection and insufficient milk and vegetables in the diet are of particular importance for the development of fluorosis. The disease is also determined by the socio-cultural living conditions of the population. This disease was first recorded in India, but among the British and the local aristocracy, fluorosis was rare, although the fluoride content in the water was 2-3 mg/l. Among the Indians, who eked out a half-starved existence, enamel spotting was already detected in those areas where the fluoride content was even 1.5 mg per 1 liter.

Preventive measures regarding the effects of fluoride can be considered:

1) drinking water with a high content of mineral salts;

2) consumption of food and liquids with a high calcium content (vegetables and dairy products), since calcium binds fluorine and converts it into the insoluble complex Ca + F = CaF 2;

3) the protective role of vitamins;

4) ultraviolet irradiation;

5) water defluoridation.

Fluorosis is a general disease of the entire body, although it is most clearly manifested in damage to the teeth. However, with fluorosis the following are noted:

1) disturbance (inhibition) of phosphorus-calcium metabolism;

2) disruption (inhibition) of the action of intracellular enzymes (phosphatases);

3) violation of the immunobiological activity of the body.

The following stages of fluorosis are distinguished:

1 – appearance of chalky spots;

2 – appearance of pigment spots;

3 and 4 – the appearance of defects and erosions of enamel (dentin destruction).

The fluoride content in water is standardized by the standard, since water with a low fluoride content of 0.5-0.7 mg/l is harmful, as dental caries develops. Rationing is carried out by climatic regions, depending on the level of water consumption. In the 1st-2nd region - 1.5 mg/l, in the 3rd - 1.2 mg/l, in the 4th - 0.7 mg/l. Caries affects 80-90% of the entire population. This is a potential source of infection and intoxication. Caries leads to digestive disorders and chronic diseases of the stomach, heart and joints. Convincing evidence of the anti-caries effect of fluoride is the practice of water fluoridation. With a fluoride content of 1.5 mg/l, the incidence of caries is the lowest. In Norilsk, after 7 years of water fluoridation, the incidence of caries in 7-year-old children was 43% lower. People who drink fluoridated water throughout their lives have a 60-70% lower incidence of caries. On the island of New Guinea, people do not have caries, since the fluoride content in drinking water is optimal.

A number of chemicals cause microchemical pollution, or water intoxication

Thus, there is a group of atherogenic elements (copper, cadmium, lead), the excess of which has an adverse effect on the cardiovascular system.

Moreover, lead in children crosses the blood-brain barrier, causing brain damage. Lead displaces calcium from bone tissue.

Mercury causes Minamata disease (severe embryotoxic effect).

Cadmium causes Itai-Itai disease (lipid metabolism disorder).

Metals with dangerous embryotoxic effects form a gonadotoxic series, which looks like this: mercury – cadmium – thallium – silver – barium – chromium – nickel – zinc.

Arsenic has a pronounced ability to cumulate in the body, its chronic effect is associated with effects on the peripheral nervous system and the development of polyneuritis.

Bor has a pronounced gonadotoxic effect. It disrupts the sexual activity of men and the ovarian-menstrual cycle in women. The natural underground waters of Western Siberia are rich in boron.

A number of synthetic materials used in water supply can cause intoxication. These are primarily synthetic pipes, polyethylene, phenol-formaldehydes, coagulants and flocculants (PAA), resins and membranes used in desalination. Toxic chemicals, carcinogenic substances, and nitrosamines that get into water are hazardous to health.

surfactants(synthetic surfactants) are stable in water and slightly toxic, but have an allergenic effect, and also contribute to better absorption of carcinogens and toxic chemicals.

When using water containing high concentrations of nitrates, young children infancy develop water-nitrate methemoglobinemia. A mild form of the disease can also occur in adults. This disease is characterized by indigestion in children (dyspepsia), a decrease in the acidity of gastric juice. In this regard, in the upper intestine, nitrates are reduced to nitrites NO 2. Nitrates enter drinking water due to widespread chemicalization of agriculture and the use of nitrogenous fertilizers. In children, gastric juice pH = 3, which promotes the reduction of nitrates into nitrites and the formation of methemoglobin. In addition, children lack the enzymes that reduce methemoglobin to hemoglobin. The intake of nitrates from infant formula prepared with contaminated water is very dangerous.

Salt composition is a factor that constantly and long-term affects the health of the population. This is a low intensity factor. The influence of chloride, chloride-sulfate and hydrocarbonate types of water on:

1) water-salt metabolism;

2) purine metabolism;

3) decrease in secretory and increase in motor activity of the digestive organs;

4) urination;

5) hematopoiesis;

6) cardiovascular diseases (hypertension and atherosclerosis).

Increased salt composition of water

affects unsatisfactory organoleptic properties, which leads to a decrease in “water appetite” and limitation of its consumption.

Increased hardness (15-20 mg eq/l) is one of the factors in the development of urolithiasis; and leads to the development of endemic urolithiasis;

It is difficult to use water of increased hardness for economic, domestic purposes, and irrigation;

With long-term consumption of highly mineralized chloride waters, there is an increased hydrophobicity of tissues, their ability to retain water, and tension in the pituitary-adrenal system;

The use of chloride class water with a total mineralization level of more than 1 g/l causes hypertensive conditions. !

The influence of water with low mineralization (desalinated, distilled) causes:

1) violation of water-salt metabolism (decreased chlorine metabolism in tissues);

2) changes in the functional state of the pituitary-adrenal system, tension in protective-adaptive reactions;

3) lag in growth and body weight. The minimum permissible level of total mineralization of desalinated water must be at least 100 mg/l.

The balance of water in the body consists of its consumption and excretion. Water in an adult makes up 55-60% of body weight, and in a newborn – 75%. The bulk (about 71%) of all water in the body is part of the intracellular fluid. Extracellular water is part of tissue or interstitial fluid (about 21%) and blood plasma water (about 8%).

An adult consumes about 2.5 liters of water per day; in addition, approximately 300 ml of metabolic water is formed in the body. This water is formed during the metabolic process during the oxidation of proteins, carbohydrates and fats.

Water is excreted through urine (on average 1.5 liters per day), through exhaled air, through the skin (under conditions of neutral temperature without sweating - 0.9 liters) and with feces (0.1 liters). Under normal conditions, the amount of water involved in metabolism in the human body does not exceed 5% of body weight per day.

Functions of water in the body.

1. Constitutional water is a component of the cells and tissues of the body. It is the environment in which metabolic processes take place in cells, organs and tissues. A continuous supply of water to the body is one of the main conditions for maintaining life.

2. Water is the best solvent for many biologically important substances; it provides conditions for the formation of dispersed forms of lipids and proteins; is the main medium and an obligatory participant in many biochemical reactions (free water).

3. Insufficient water content in the body (dehydration) can lead to thickening of the blood, deterioration of its rheological properties, and disruption of blood flow. When the amount of water decreases by 20%, death occurs. Excess water can lead to the development of water intoxication, which manifests itself, in particular, in cell swelling and a decrease in osmotic pressure in them. Nerve cells in the brain are especially sensitive to such changes.

4. By promoting the hydration of macromolecules, water participates in their activation (bound water).

5. By dissolving the end products of metabolism, water promotes their excretion by the kidneys and other excretory organs.

6. Water ensures the body’s adaptation to high ambient temperatures.

Biological value of water.

Drinking water is the most important source of calcium, magnesium, and a number of microelements. Their absorption and biological value may be higher than when they are absorbed from the breakdown products of nutrients. Since in boiled water the content of mineral components is reduced, its constant use instead of raw water increases the load on the organs of water-salt metabolism due to the reabsorption of ions, which increases the risk of developing certain diseases.

In a living organism, part of the water, interacting with tissues, organizes its structure. Structured water a person receives from fresh plant and animal products, as well as when drinking freshly melted water, which has higher biological activity than ordinary water. Experiments on animals have shown its effect on microsomes and mitochondria of hepatocytes, an inhibitory effect on the absorption of carbohydrates from the intestine, an increase in the stability of erythrocytes, and an adaptogenic effect. Workers in hot shops under the influence of such water are better able to tolerate the effects of negative factors in the working environment on their bodies.

Heavy water, differing from the usual high content of deuterium oxide (heavy isotope of hydrogen) and high specific gravity, it has a different biological effect compared to ordinary water. With an experimental increase in the concentration of deuterium oxide in water, the excitability of the central nervous system increases, and adrenaline emissions to stress stimuli increase. Heavy water has been shown to have a radioprotective effect.

The supply of water is regulated by its need, manifested by a feeling of thirst. Thirst is the body's response to increased osmotic pressure and decreased fluid volumes.

Thirst may result from:

1. Increase in osmotic pressure of cellular fluid, decrease in cell volume, decrease in the volume of extracellular fluid. These changes may develop interconnectedly.

2. Drying of the oral mucosa; the latter is the result of a decrease in salivation, a consequence of fluid loss when talking, shortness of breath, smoking, etc.

3. Actions of angiotensin and natriuretic hormone.

Subjectively, thirst is experienced as one of the most powerful human drives.

The mechanism of thirst quenching, or water saturation, has not been fully disclosed. In the form of primary saturation, it occurs during the drinking process before water is absorbed. Apparently, this phenomenon, like primary satiation with food, develops due to stretching of the walls of the stomach and stimulation of its mechanoreceptors. Secondary (true) water saturation is formed when the parameters of water-salt homeostasis are restored as a result of the absorption of ingested water.

The exact localization of the volume regulation center in the brain has not yet been established. It is believed that it is located in the nuclei of the hypothalamus and midbrain. This center has afferent connections with the periphery, realized with the help of volumetric receptors (volumoreceptors) and osmoreceptors. Volume receptors are found mainly in low pressure vessels (pulmonary veins) and in the atria. They respond to significant volumetric shifts reaching ± 10%.

The body needs a constant supply of not only water, but also mineral salts.

Physico-chemical characteristics of water. Chemically pure water is a clear, odorless and tasteless liquid. A water molecule contains 11.19% hydrogen and 88.81% oxygen. The molecular weight of water is 18.016, the freezing point is 0°C, the boiling point is +100°C, the density of water at 4°C is -1 g/cm 3 .

Water is an excellent solvent for many organic and mineral substances, which is due to the structure of its molecule. Water is characterized by hydrogen bonding, which largely determines its properties and significance. Hydrogen bonds occur between the partial negative charge of the oxygen atom of one water molecule and the partial positive charge of the hydrogen atom of the neighboring one. The concentration of hydrogen ions in biological systems is expressed through the hydrogen index - pH. There are fresh, brackish and salt water. Water contains inorganic ions and organic impurities.

Content and distribution of water in the body of animals. In adult mammals and birds, water makes up about 65%, or 2/3 of the live body weight, in newborns its content reaches 70 - 80%, and in embryos - 87 - 97%. Individual organs and tissues contain different amounts of water - most of it is in the most actively functioning organs. An animal can live with a complete absence of fat reserves and up to 50% of proteins, but the loss of only 10% of water causes severe pathological changes, and the loss of 15-20% of it entails death. The need for water and its distribution in tissues varies depending on the composition of the feed, the physiological state of the animal, productive activity, the intensity of physical work, environmental conditions, etc. In young growing animals, the need for water is several times greater.

Water is distributed unequally in the tissues and organs of an animal. Different organs and tissues differ in water content. For example, bones contain 22% water, cartilage - 55, lungs - 79.1, cerebral cortex - 83.3%. Biological fluids are characterized by a high water content - up to 99.5% (saliva, sweat). About 72% of all body water is concentrated in cells, 28% in intercellular fluids, 8-10% in blood plasma, lymph, cerebrospinal fluid, synovium, and pleural fluid. It should be taken into account that per 1 kg of animal weight an average of 35-40 g of water per day is required. In young organisms this need is 2-4 times higher.

Animals' need for water is satisfied mainly by receiving it directly from the outside and by eating succulent feed. A small amount of water is formed in tissues. From the intestines, where the bulk of water is absorbed, it enters the liver. Part of it is retained in the liver as a reserve, and the rest is carried away by the bloodstream to other organs and tissues. From the latter, it returns to the blood again.

The body of a cow, for example, takes in 40-50 liters of water per day; in addition, another 120-130 liters of water are released into the gastrointestinal tract as part of the digestive juices. Of this entire volume, only about 10% of the liquid is excreted in the feces, and the rest is reabsorbed into the blood. Water coming from outside must completely compensate for its constant losses through urine, sweat, secretions (milk), and exhaled air.

Biological significance of water. Water in the body performs a number of vital functions. First of all, she is universal solvent mineral and organic substances included in feed, and metabolic products. Water - plastic material, from which organs, tissues and cells are built.

The multiple functions of water are determined by its physicochemical properties. Water molecules, like dipoles, are associated with each other using hydrogen bonds. A significant amount of energy is spent on breaking these bonds, which gives water a high heat capacity (in water it is 4 times higher than in air, which is the “external environment” of most higher animals). Due to this, water plays an important role in the processes thermoregulation organisms. About 25% of excess thermal energy is released from the body as a result of the evaporation of water from the surface of the skin. Approximately the same amount of heat is released from the body with exhaled air vapor.

water molecules participate in the creation of secondary and tertiary structures protein molecules. All feed nutrients are absorbed in the food channel with the participation of water (hydrolysis reactions). Water is characterized by a very low viscosity, which gives aqueous solutions good fluidity and rapid movement of fluids in the body. Water and its solutions wet rubbing surfaces, helping to improve their gliding.

Conditions and types of water in the body. The water contained in the body is conventionally divided into free and immobilized. Free water is found in blood plasma, lymph, cerebrospinal fluid, digestive juices, and urine. There is relatively little of it in the intercellular spaces and it is held there by capillary forces. Free water ensures the influx of nutrients into tissues and the removal of final metabolic products from them.

Immobilized water there are two types: hydration And immobile. Unlike free water, it lacks the ability to move freely, and a smaller part of it is firmly bound to the polar groups of proteins and other biopolymers (hydration water). It makes up about 4% of all tissue water, 10-80% of this water is bound by proteins. Tissue proteins are so actively hydrated that for every 100 g they can bind from 18 to 50 g of water. Hydration water differs from free water in a number of ways. It does not freeze when cooled to 0°C and slightly lower, has an increased density (1.48-2.45), and substances soluble in ordinary water do not dissolve in it. These differences are due to the ordered arrangement of water molecules (dipoles) around the polar groups of hydrophilic colloids.

The other part of the immobilized water (immobile), although not bound by polar groups, is deprived of the ability to move freely, since it is enclosed in supramolecular cellular structures (membranes, organelles, fibrillar aggregates). Its molecules are located between cell membranes, fibrous molecules and structures. Such water retains the ability to dissolve salts and other soluble substances, ensures a high rate of chemical reactions in tissues, gives elasticity to tissues, and helps them maintain a constant shape. Solvation (hydration) of tissue proteins and immobilization of water by fibrillar and membrane structures prevents the latter from leaking out during tissue dissection.

With age, the amount of hydration water in the body gradually decreases due to a decrease in the ability of colloids to hydrate. This leads to the fact that the cytoplasmic colloids gradually undergo syneresis, as a result of which the tissues lose their elasticity and shrink. There is a dynamic balance between different types of water. The amount of free water increases in pathology (with nephritis, pericarditis, abscesses, phlegmon). Swelling occurs. During short-term work (10-15 minutes), intercellular (free) water accumulates in the body; during long-term work (over 30-60 minutes), intracellular (immobile) water accumulates.

Types of water. Tissues and cells use two types of water: exogenous and endogenous. Exogenous water enters the body from the outside - with food and drink. In total, it makes up 6/7 of all the water necessary for the life of the body. 1/7 of the total mass of water is formed in animal tissues as the final product of the oxidation of nucleic acids, proteins, lipids, and carbohydrates. This endogenous water. It has been established that with the complete oxidation of 100 g of fat, the body receives 107.1 g of water, carbohydrates - 55.6 and proteins - 41.3 g of water. The quantitative ratio of exogenous and endogenous water in the body depends on the type and age of the animal, the level of its productivity and environmental conditions (ambient temperature, humidity, habitat area), diet, season of the year, etc. The endogenous way the body obtains water is of great importance for the inhabitants waterless deserts and steppes, for animals that hibernate.

The importance of the topic of water consumption by the population is emphasized by in-depth study of the problem by organizations such as the World Health Organization (WHO), the United Nations (UN) and other international societies, concerned about the lack of quality drinking water for residents of many countries, especially the countries of Central Asia and Eastern Europe.

In modern conditions, it seems that the need for constant consumption of water is known and undeniable to everyone. However, doctors are still faced with the fact that the amount of water that patients drink is significantly less than the norms accepted in the world.

The percentage of water that is in the human body depends on his age: in a young person, water is up to 70%, and in an elderly person it is about 45%. This difference in numbers is explained by the fact that the total water content in the body decreases with age. Thus, in a newborn child, the amount of water in the body is approximately 75%, while in women and men over the age of 50 this figure is closer to 47% and 56%, respectively.

Men have a greater amount of water in the body than women, mainly due to the greater body weight of the stronger sex. In the body of any person, the distribution of water is uneven: bone and adipose tissue contain the least amount of water (10% and 20%, respectively), but the internal organs are the richest in water (in the kidneys - 83%, in the liver - 68%).

Most of the body's water is found in cells (intracellular fluid) and accounts for 35 - 45% of the total body weight. Internal - vascular, intercellular and transcellular fluid total 15-25% of body weight and are collectively called extracellular fluid. Thus, water is the main component of the internal environment of the body; without it, maintaining its basic vital functions would be impossible.

The main functions of water in the human body

1. Metabolic function. Water is a polar solvent and serves as a medium for biochemical reactions. Water may also be the end product of many of these reactions.
2. Transport function. Water has the ability to transport molecules in the intracellular space, and also ensures the transport of molecules from one cell to another.
3. Thermoregulatory function. The uniform distribution of heat inside the body occurs precisely thanks to water. When sweating, the body is cooled by evaporating fluid, which is of great importance for the processes of physical thermoregulation.
4. Excretory function. Water is involved in the removal of metabolic products.
5. Water is part of lubricating fluids and mucus, and is a component of body juices and secretions.

It is important that without water it is impossible to maintain water-electrolyte balance, which is the basis for the normal functioning of the human body.

Water-electrolyte metabolism is the processes of absorption, distribution, consumption and excretion of water and salts in the body. It is water that is responsible for maintaining constant osmotic pressure, ionic composition and acid-base state of the internal environment.

To obtain water that is safe in all respects, you should carefully select the place of its extraction. Unfortunately, spring water cannot best meet drinking water quality standards, because it comes from water carriers closest to the surface.

Due to the shallow location in the springs, rainwater and melted snow are filtered; this water may contain nitrates, radionuclides, lead, mercury, cadmium, radioactive elements and industrial wastewater (and sometimes even sewage). The greatest danger comes from water from sources with a small supply of water and from those where it is collected slowly and the surface of the source is open.

The best water for consumption is considered to be water from artesian springs located at a depth of 100 m. Such water has favorable sanitary and epidemic indicators and is healthy for consumption.

Before water is used for food, it is usually treated using various methods. The purpose of water treatment is to remove hazardous elements from its composition that can cause diseases. Water purification should not significantly change its composition. It is also unacceptable to form any side compounds during cleaning that quantitatively exceed the established sanitary and hygienic standards.

The conditions for water extraction are important, since at this stage there is a risk of its contamination. Therefore, everything that comes into contact with water during its extraction (for example, water intake, pipes and tanks) must be made of special materials suitable for use in contact with water. The extraction conditions (washing installation and water dispensing) must be made in such a way as not to adversely affect the microbiological and physicochemical characteristics of the water.

Under normal conditions, water intake into the body is ensured by drinking water and drinks (tea, coffee, sweet, carbonated drinks) - about 80% and eating food (liquid and solid) - 20%. We must not forget about endogenous water formed as a result of metabolism, the production of which can significantly increase during physical activity.

Loss of water in the body occurs primarily through excretion by the kidneys and through sweating. Other ways of losing fluid are through the skin, lungs and stool. If the amount of water in the body decreases, its deficiency is compensated by drinking drinks, food and metabolically produced fluid. If water loss is no more than 0.2% of body weight, its compensation occurs within 24 hours. A deficiency of 10% of water leads to irreversible pathological changes in the body.

The water cycle in the adult body varies depending on indicators such as climate, physical activity, gender, and age. Thus, the water cycle for a man with a predominantly sedentary lifestyle is 3.2 liters per day, and for a man who adheres to active image life - 4.5 liters per day. Women have a significantly lower water cycle in the body: 3.5 liters per day and 1.0 liters per day, respectively.