Inorganic ions, or minerals, perform the following functions in the body:

1. Bioelectric function. This function is associated with the occurrence of a potential difference on cell membranes. The ion concentration gradient on both sides of the membrane creates a potential of about 60-80 mV in different cells. The inner side of the cell membrane is negatively charged relative to the outer. The higher the electrical potential of the membrane, the higher the protein content and its ionization (negative charge) inside the cell and the concentration of cations outside the cell (the diffusion of Na + and K + ions through the membrane into the cell is difficult). This function of inorganic ions is used to regulate the functions of especially excitable cells (nerve, muscle) and to conduct nerve impulses.

2. Osmotic function used to regulate osmotic pressure. A living cell obeys the law of isosmopolarity: in all environments of the body, between which there is a free exchange of water, the same osmotic pressure is established. If the number of ions in a certain medium increases, then water rushes after them until a new equilibrium and a new level of osmotic pressure are established.

3. Structural function due to the complexing properties of metals. Metal ions interact with anionic groups of proteins, nucleic acids and other macromolecules and thereby ensure, along with other factors, the maintenance of certain conformations of these molecules. Since the biological activity of biopolymers depends on their conformations, the normal implementation of their functions by proteins, the unhindered implementation of information contained in nucleic acids, the formation of supramolecular complexes, the formation of subcellular structures and other processes are unthinkable without the participation of cations and anions.

4. Regulatory function is that metal ions are enzyme activators and thereby regulate the rate of chemical transformations in the cell. This is a direct regulatory effect of cations. Indirectly, metal ions are often necessary for the action of another regulator, for example, a hormone. Let's give a few examples. The formation of the active form of insulin is impossible without zinc ions. The tertiary structure of RNA is largely determined by the ionic strength of the solution, and cations such as Cr 2+, Ni 2+, Fe 2+, Zn 2+, Mn 2+ and others are directly involved in the formation of the helical structure of nucleic acids. The concentration of Mg 2+ ions affects the formation of such a supramolecular structure as ribosomes.

5. Transport function manifests itself in the participation of certain metals (as part of metalloproteins) in the transfer of electrons or simple molecules. For example, iron and copper cations are part of cytochromes, which are carriers of electrons in the respiratory chain, and iron in hemoglobin binds oxygen and participates in its transfer.

6. Energy function associated with the use of phosphate anions in the formation of ATP and ADP (ATP is the main carrier of energy in living organisms).

7. Mechanical function. For example, the Ca +2 cation and phosphate anion are part of the hydroxylapatite and calcium phosphate of bones and determine their mechanical strength.

8. Synthetic function. Many inorganic ions are used in syntheses complex molecules. For example, iodine ions I¯ are involved in the synthesis of iodothyronines in thyroid cells; anion (SO 4) 2- - in the synthesis of ester-sulfur compounds (during the neutralization of harmful organic alcohols and acids in the body). Selenium is important in the mechanism of protection against the toxic effects of peroxide. It forms selenocysteine, an analogue of cysteine, in which selenium atoms replace sulfur atoms. Selenocysteine ​​is a component of the enzyme glutathione peroxidase, which catalyzes the reduction of hydrogen peroxide with glutathione (tripeptide - γ-glutamyl-cysteinylglycine)

It is important to note that, within certain limits, interchangeability of some ions is possible. If there is a deficiency of a metal ion, it can be replaced by another metal ion that is similar in physicochemical properties and ionic radius. For example, the sodium ion is replaced by a lithium ion; calcium ion - strontium ion; molybdenum ion - vanadium ion; iron ion - cobalt ion; sometimes magnesium ions - manganese ions.

Due to the fact that minerals activate the action of enzymes, they affect all aspects of metabolism. Let us consider how the metabolism of nucleic acids, proteins, carbohydrates and lipids depends on the presence of certain inorganic ions.

Minerals - this is one of the most important components of our nutrition, without them the correct flow of vital processes in the body is impossible, they ensure the correct formation of the chemical structure of all human tissues and, of course, muscle tissue, including. All minerals, present in our body, can be divided into macroelements and microelements.

Macronutrients– mineral substances contained in the body in relatively large quantities are: iron, calcium, sodium, phosphorus, magnesium, potassium, sulfur, chlorine.

Microelements– mineral substances contained in the body in relatively small quantities are: zinc, manganese, copper, fluorine, chromium, nickel, cobalt and others.

Substances	Location and transformation	Properties
Nitrogen compounds	In plant cells, ammonium and nitrate ions are reduced and included in the synthesis of amino acids. In animals, amino acids are used to build their own proteins. When organisms die, they are included in the cycle of substances in the form of free nitrogen.	Contains proteins, amino acids, nucleic acids (DNA, RNA) and ATP
Phosphorus compounds	Fluorine salts (phosphates) being in the soil are dissolved by plant root secretions and are absorbed. When organisms die, the remains of phosphoric acid are mineralized, forming salts.	They are part of all membrane structures; nucleic acids, DNA, RNA, ATP, tissue enzymes (bone)
Potassium compounds	Potassium is contained in all cells in the form of potassium ions, the concentration of which is much higher than in environment. After dying, it returns to the environment in the form of potassium ions.	The cell's "potassium pump" promotes penetration through the membrane. Activates the vital activity of the cell, the conduction of excitation and impulses.
Calcium compounds	Calcium is contained in cells in the form of ions and salt crystals.	Forms intercellular substance and crystals in plant cells. Part of bones, shells, calcareous skeletons

The vital activity of a cell is characterized by metabolic processes continuously occurring in it, and the cytoplasm selectively reacts to the influence of various environmental factors. The processes of diffusion and osmosis play an important role in the absorption and release of substances. The selectivity of transport through a permeable membrane leads to the occurrence of osmotic phenomena in the cell. Osmotic call the phenomena occurring in a system consisting of two solutions separated by a semi-permeable membrane. In a plant cell, the role of semi-permeable films is performed by: plasmalemma - a membrane separating the cytoplasm and the extracellular environment, and tonoplast - a membrane separating the cytoplasm and cell sap, which is the contents of the vacuole.

Osmosis - the diffusion of water through a semipermeable membrane from a solution of low solute concentration to a solution of high solute concentration. The pressure at which liquid diffusion stops is called osmotic pressure. If the osmotic pressure of a solution is greater than the pressure of the liquid being tested, the solution is called hypertensive; if less - hypotonic, if the same - isotonic.

Plant cell turgor. If you place adult plant cells (as part of tissue, for example, the epidermis) in hypotonic conditions, they will not burst, since each plant cell is surrounded by a more or less thick cell wall. It serves as a rigid structure that prevents incoming water from tearing the cell. If the cell wall and plasma membrane of a cell could stretch, water would enter the cell until the concentration is osmotically active substances the outside and inside of the cell would not align. In reality, the cell wall is a strong, inextensible structure, and under hypotonic conditions, water entering the cell presses on the cell wall, tightly pressing the plasmalemma against it. The pressure of the protoplast from the inside on the cell wall is called turgorous pressure. Plant cells have turgidity. Turgor pressure prevents further water from entering the cell. The state of internal tension of the cell, due to the high water content and the developing pressure of the cell contents on its membrane is called turgor.

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Presentation on the subject "biology". Topic: “Mineral substances and their role in the cell.” The presentation was prepared by 10th grade student Noikova E. Teacher: Danilkina O.N.

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Macroelements include sodium, potassium, calcium, magnesium, chlorine, silicon, sulfur, iron, etc. Microelements include substances whose content in products is negligible - iodine, zinc, copper, fluorine, bromine, manganese, etc. Despite low content, microelements are extremely important for human nutrition. Along with organic substances - proteins, carbohydrates, fats - the cells of living organisms contain compounds that make up a wide group of mineral substances. These include water and various salts, which, when in a dissolved state, dissociate (break up) to form ions: cations (positively charged) and anions (negatively charged). Minerals are part of all cells, tissues, bones; they maintain acid-base balance in the body and have big influence on metabolism. Minerals, depending on their content in foods or the human body, are conventionally divided into macroelements and microelements.

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Many minerals are essential structural elements body - calcium and phosphorus make up the bulk of the mineral matter of bones and teeth, sodium and chlorine are the main ions of plasma, and potassium is found in large quantities inside living cells. Maintaining Consistency internal environment(homeostasis) of the body and osmotic pressure on cell membranes, primarily involves maintaining the qualitative and quantitative content of minerals in tissues and organs at a physiological level. Even small deviations from the norm can lead to the most severe consequences for the health of the body or an individual cell. The entire set of macro and microelements ensures the processes of growth and development of the body. Minerals play an important role in regulating immune processes, maintaining the integrity of cell membranes, and ensuring tissue respiration.

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Inorganic ions: cations and anions Cations – potassium, sodium, magnesium and calcium. The anions are chloride anion, bicarbonate anion, hydrogen phosphate anion, dihydrogen phosphate anion, carbonate anion, phosphate anion and nitrate anion. Let's consider the meaning of ions. Ions, located along different sides cell membranes form the so-called transmembrane potential. Many ions are unevenly distributed between the cell and the environment. Thus, the concentration of potassium ions (K+) in the cell is 20–30 times higher than in the environment; and the concentration of sodium ions (Na+) is ten times lower in the cell than in the environment. Thanks to the existence of concentration gradients, many vital processes take place, such as contraction of muscle fibers, excitation of nerve cells, and transfer of substances across the membrane. Cations affect the viscosity and fluidity of the cytoplasm. Potassium ions reduce viscosity and increase fluidity, calcium ions (Ca2+) have the opposite effect on the cell cytoplasm. Anions of weak acids - bicarbonate anion (HCO3-), hydrogen phosphate anion (HPO42-) - are involved in maintaining the acid-base balance of the cell, that is, the pH of the environment. According to their reaction, solutions can be acidic, neutral or basic.

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pH of the environment and the role of ions in its maintenance The pH value in the cell is approximately equal to 7. A change in pH in one direction or another has a detrimental effect on the cell, since the biochemical processes taking place in the cell immediately change. The constant pH of the cell is maintained due to the buffering properties of its contents. A buffer solution is a solution that supports constant value pH of the environment. Typically, a buffer system consists of a strong and weak electrolyte: a salt and a weak base or weak acid that form it. The effect of a buffer solution is that it resists changes in the pH of the environment. A change in the pH of the medium can occur as a result of concentrating the solution or diluting it with water, acid or alkali. When acidity, that is, the concentration of hydrogen ions, increases, free anions, the source of which is the salt, interact with protons and remove them from the solution.

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pH of the environment and the role of ions in its maintenance When acidity decreases, the tendency to release protons increases. In this way, the pH is maintained at a certain level, that is, the concentration of protons is maintained at a certain constant level. Some organic compounds, in particular proteins, also have buffering properties. Cations of magnesium, calcium, iron, zinc, cobalt, manganese are part of enzymes and vitamins. Metal cations are part of hormones. Zinc is part of insulin. Insulin is a pancreatic hormone that regulates blood glucose levels. Magnesium is part of chlorophyll. Iron is part of hemoglobin. With a lack of these cations, the vital processes of the cell are disrupted

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Blood buffer system In the human body there are always certain conditions for shift normal reaction the environment of the tissue, for example, blood, towards acidosis (acidification) or alkalosis (deoxidation - a shift in pH upward). Various products enter the blood, for example, lactic acid, phosphoric acid, sulfurous acid, formed as a result of the oxidation of organophosphorus compounds or sulfur-containing proteins. In this case, the blood reaction may shift towards acidic foods. When eating meat products, acidic compounds enter the blood. When eating plant foods, bases enter the blood. However, the pH of the blood remains at a certain constant level. There are buffer systems in the blood that maintain pH at a certain level. Blood buffer systems include: - carbonate buffer system, - phosphate buffer system, - hemoglobin buffer system, - plasma protein buffer system.

The cell consists of organic and mineral substances.

Mineral composition of cells

From not organic matter the cell contains 86 elements periodic table, about 16-18 elements are vital for the normal existence of a living cell.

Among the elements there are: organogens, macroelements, microelements and ultramicroelements.

Organogens

These are the substances that make up organic matter: oxygen, carbon, hydrogen and nitrogen.

Oxygen(65-75%) - contained in a huge number organic molecules- proteins, fats, carbohydrates, nucleic acids. As simple substance(O2) is formed during oxygenic photosynthesis (cyanobacteria, algae, plants).

Functions: 1. Oxygen is a strong oxidizing agent (oxidizes glucose during cellular respiration, energy is released in the process)

2. Part of the organic substances of the cell

3. Part of the water molecule

Carbon(15-18%) - is the basis of the structure of all organic substances. As carbon dioxide released during respiration and absorbed during photosynthesis. May be in the form of CO - carbon monoxide. In the form of calcium carbonate (CaCO3) it is part of bones.

Hydrogen(8 - 10%) - like carbon, it is part of any organic compound. It is also part of the water.

Nitrogen(2 - 3%) - is part of amino acids, and therefore proteins, nucleic acids, some vitamins and pigments. Fixed by bacteria from the atmosphere.

Macronutrients

Magnesium (0,02 - 0,03%)

1. In the cell - part of enzymes, involved in DNA synthesis and energy metabolism

2. In plants - part of chlorophyll

3. In animals - part of the enzymes involved in the functioning of muscle, nervous and bone tissues.

Sodium (0,02 - 0,03%)

1. In the cell - part of potassium-sodium channels and pumps

2. In plants - participates in osmosis, which ensures the absorption of water from the soil

3. In animals - participates in kidney function, maintaining heart rhythm, is part of the blood (NaCl), helps maintain acid-base balance

Calcium (0,04 - 2,0%)

1. In the cell - participates in the selective permeability of the membrane, in the process of connecting DNA with proteins

2. In plants - forms salts of pectin substances, gives hardness to the intercellular substance connecting plant cells, and also participates in the formation of intercellular contacts

3. In animals - part of the bones of vertebrates, mollusk shells and coral polyps, participates in the formation of bile, increases reflex excitability spinal cord and the center of salivation, participates in the synaptic transmission of nerve impulses, in blood coagulation processes, is a necessary factor in the contraction of striated muscles

Iron (0,02%)

1. In the cell - part of cytochromes

2. In plants - participates in the synthesis of chlorophyll, is part of enzymes involved in respiration, is part of cytochromes

3. In animals - part of hemoglobin

Potassium (0,15 - 0,4%)

1. In the cell - maintains the colloidal properties of the cytoplasm, is part of potassium-sodium pumps and channels, activates enzymes involved in protein synthesis during glycolysis

2. In plants - participates in the regulation of water metabolism and photosynthesis

3. Necessary for proper heart rhythm, participates in the conduction of nerve impulses

Sulfur (0,15 - 0,2%)

1. In the cell - it is part of some amino acids - citine, cysteine ​​and methionine, forms disulfide bridges in the tertiary structure of protein, is part of some enzymes and coenzyme A, is part of bacteriochlorophyll, some chemosynthetics use sulfur compounds to produce energy

2. In animals - part of insulin, vitamin B1, biotin

Phosphorus (0,2 - 1,0%)

1. In the cell - in the form of phosphoric acid residues it is part of DNA, RNA, ATP, nucleotides, coenzymes NAD, NADP, FAD, phosphorylated sugars, phospholipids and many enzymes; it forms membranes as part of phospholipids

2. In animals - part of bones, teeth, in mammals it is a component of the buffer system, maintains the acid balance of tissue fluid relatively constant

Chlorine (0,05 - 0,1%)

1. In the cell - participates in maintaining the electroneutrality of the cell

2. In plants - participates in the regulation of turgor pressure

3. In animals - participates in the formation of the osmotic potential of blood plasma, as well as in the processes of excitation and inhibition in nerve cells, is part of the gastric juice in the form of hydrochloric acid

Microelements

Copper

1. In the cell - part of the enzymes involved in the synthesis of cytochromes

2. In plants - part of the enzymes involved in the reactions of the dark phase of photosynthesis

3. In animals - participates in the synthesis of hemoglobin, in invertebrates it is part of hemocyanins - oxygen carriers, in humans - it is part of the skin pigment - melanin

Zinc

1. Participates in alcoholic fermentation

2. In plants - part of the enzymes involved in the breakdown of carbonic acid and in the synthesis of plant hormones-auxins

Iodine

1. In vertebrates - part of the thyroid hormones (thyroxine)

Cobalt

1. In animals - part of vitamin B12 (takes part in the synthesis of hemoglobin), its deficiency leads to anemia

Fluorine

1. In animals - gives strength to bones and tooth enamel

Manganese

1. In the cell - part of the enzymes involved in respiration, oxidation fatty acids, increases carboxylase activity

2. In plants - as part of enzymes, it participates in dark reactions of photosynthesis and in the reduction of nitrates

3. In animals - part of the phosphatase enzymes necessary for bone growth

Bromine

1. In the cell - part of vitamin B1, which is involved in the breakdown of pyruvic acid

Molybdenum

1. In the cell - as part of enzymes, it participates in the fixation of atmospheric nitrogen

2. In plants - as part of enzymes, it participates in the work of stomata and enzymes involved in the synthesis of amino acids

Bor

1. Affects plant growth

From this lesson you will learn about the role of mineral compounds of micro- and macroelements in the life of living organisms. You will get acquainted with the hydrogen indicator of the environment - pH, learn how this indicator is related to the physiology of the body, how the body maintains a constant pH of the environment. Find out the role of inorganic anions and cations in metabolic processes, learn details about the functions of Na, K and Ca cations in the body, as well as what other metals are part of our body and what their functions are.

Introduction

Topic: Basics of cytology

Lesson: Minerals and their role in cell life

1. Introduction. Minerals in the cell

Minerals constitute from 1 to 1.5% of the wet weight of the cell, and are found in the cell in the form of salts dislocated into ions, or in the solid state (Fig. 1).

Rice. 1. Chemical composition cells of living organisms

In the cytoplasm of any cell there are crystalline inclusions, which are represented by slightly soluble calcium and phosphorus salts; besides them there may be silicon oxide and other inorganic compounds, which participate in the formation of supporting structures of the cell - in the case of the mineral skeleton of radiolarians - and the organism, that is, they form the mineral substance of bone tissue.

2. Inorganic ions: cations and anions

Inorganic ions are important for the life of the cell (Fig. 2).

Rice. 2. Formulas of the main ions of the cell

Cations- potassium, sodium, magnesium and calcium.

Anions- chloride anion, bicarbonate anion, hydrogen phosphate anion, dihydrogen phosphate anion, carbonate anion, phosphate anion and nitrate anion.

Let's consider the meaning of ions.

Ions, located on opposite sides of cell membranes, form the so-called transmembrane potential. Many ions are unevenly distributed between the cell and the environment. Thus, the concentration of potassium ions (K+) in the cell is 20-30 times higher than in the environment; and the concentration of sodium ions (Na+) is ten times lower in the cell than in the environment.

Thanks to existence concentration gradients, many vital processes are carried out, such as contraction of muscle fibers, excitation of nerve cells, and transfer of substances across the membrane.

Cations affect the viscosity and fluidity of the cytoplasm. Potassium ions reduce viscosity and increase fluidity, calcium ions (Ca2+) have the opposite effect on the cell cytoplasm.

Anions of weak acids - bicarbonate anion (HCO3-), hydrogen phosphate anion (HPO42-) - are involved in maintaining the acid-base balance of the cell, that is pHenvironment. According to their reaction, solutions can be sour, neutral And main.

The acidity or basicity of a solution is determined by the concentration of hydrogen ions in it (Fig. 3).

Rice. 3. Determination of the acidity of a solution using a universal indicator

This concentration is expressed using the pH value, the scale ranges from 0 to 14. Neutral environment pH - about 7. Acidic - less than 7. Basic - more than 7. You can quickly determine the pH of the medium using indicator papers or strips (see video).

We dip the indicator paper into the solution, then remove the strip and immediately compare the color of the indicator zone of the strip with the colors of the standard comparison scale that is included in the kit, assessing the similarity of the color and determining the pH value (see video).

3. pH of the environment and the role of ions in its maintenance

The pH value in the cell is approximately 7.

A change in pH in one direction or another has a detrimental effect on the cell, since the biochemical processes taking place in the cell immediately change.

The constancy of the cell pH is maintained thanks to buffer properties its contents. A buffer solution is a solution that maintains a constant pH value. Typically, a buffer system consists of a strong and weak electrolyte: a salt and a weak base or weak acid that form it.

The effect of a buffer solution is that it resists changes in the pH of the environment. A change in the pH of the medium can occur as a result of concentrating the solution or diluting it with water, acid or alkali. When acidity, that is, the concentration of hydrogen ions, increases, free anions, the source of which is the salt, interact with protons and remove them from the solution. When acidity decreases, the tendency to release protons increases. In this way, the pH is maintained at a certain level, that is, the concentration of protons is maintained at a certain constant level.

Some organic compounds, in particular proteins, also have buffering properties.

Cations of magnesium, calcium, iron, zinc, cobalt, manganese are part of enzymes and vitamins (see video).

Metal cations are part of hormones.

Zinc is part of insulin. Insulin is a pancreatic hormone that regulates blood glucose levels.

Magnesium is part of chlorophyll.

Iron is part of hemoglobin.

With a lack of these cations, the vital processes of the cell are disrupted.

4. Metal ions as cofactors

The importance of sodium and potassium ions

Sodium and potassium ions are distributed throughout the body, while sodium ions are mainly included in the intercellular fluid, and potassium ions are contained inside cells: 95% of ions potassium contained inside cells, and 95% of ions sodium contained in intercellular fluids(Fig. 4).

Associated with sodium ions osmotic pressure fluids, tissue water retention, and transport, or transport substances such as amino acids and sugars through the membrane.

The importance of calcium in the human body

Calcium is one of the most abundant elements in the human body. The bulk of calcium is found in bones and teeth. The fraction outside bone calcium makes up 1% of the total amount of calcium in the body. Extraosseous calcium affects blood clotting, as well as neuromuscular excitability and muscle fiber contraction.

Phosphate buffer system

The phosphate buffer system plays a role in maintaining the acid-base balance of the body; in addition, it maintains the balance in the lumen of the kidney tubules, as well as intracellular fluid.

The phosphate buffer system consists of dihydrogen phosphate and hydrogen phosphate. Hydrogen phosphate binds, that is, neutralizes the proton. Dihydrogen phosphate releases a proton and interacts with alkaline products entering the blood.

The phosphate buffer system is part of the blood buffer system (Fig. 5).

Blood buffer system

In the human body, there are always certain conditions for a shift in the normal reaction of the tissue environment, for example, blood, towards acidosis (acidification) or alkalosis (deoxidation - an upward shift in pH).

Various products enter the blood, for example, lactic acid, phosphoric acid, sulfurous acid, formed as a result of the oxidation of organophosphorus compounds or sulfur-containing proteins. In this case, the blood reaction may shift towards acidic foods.

When eating meat products, acidic compounds enter the blood. When eating plant foods, bases enter the blood.

However, the pH of the blood remains at a certain constant level.

There are in the blood buffer systems, which maintain pH at a certain level.

Blood buffer systems include:

Carbonate buffer system,

Phosphate buffer system,

Hemoglobin buffer system,

Plasma protein buffer system (Fig. 6).

The interaction of these buffer systems creates a certain constant pH of the blood.

Thus, today we looked at minerals and their role in the life of the cell.

Homework

Which chemical substances called mineral? What is the importance of minerals for living organisms? What substances do living organisms mainly consist of? What cations are found in living organisms? What are their functions? What anions are found in living organisms? What is their role? What is a buffer system? What blood buffer systems do you know? What is the content of minerals in the body related to?

1. Chemical composition of living organisms.

2. Wikipedia.

3. Biology and medicine.

4. Educational center.

Bibliography

1. Kamensky A. A., Kriksunov E. A., Pasechnik V. V. General biology 10-11 grade Bustard, 2005.

2. Biology. Grade 10. General biology. A basic level of/ P. V. Izhevsky, O. A. Kornilova, T. E. Loshchilina and others - 2nd ed., revised. - Ventana-Graf, 2010. - 224 pp.

3. Belyaev D.K. Biology 10-11 grade. General biology. A basic level of. - 11th ed., stereotype. - M.: Education, 2012. - 304 p.

4. Agafonova I. B., Zakharova E. T., Sivoglazov V. I. Biology 10-11 grade. General biology. A basic level of. - 6th ed., add. - Bustard, 2010. - 384 p.