cations called positively charged ions.

Anions are called negatively charged ions.

In the process of development of chemistry, the concepts of "acid" and "base" have undergone major changes. From the point of view of the theory of electrolytic dissociation, electrolytes are called acids, during the dissociation of which hydrogen ions H + are formed, and bases are electrolytes, during the dissociation of which hydroxide ions OH - are formed. These definitions are known in the chemical literature as the Arrhenius definitions of acids and bases.

In general, the dissociation of acids is represented as follows:

where A - - acidic residue.

Such properties of acids as interaction with metals, bases, basic and amphoteric oxides, the ability to change the color of indicators, sour taste, etc., are due to the presence of H + ions in acid solutions. The number of hydrogen cations that are formed during the dissociation of an acid is called its basicity. So, for example, HCl is a monobasic acid, H 2 SO 4 is dibasic, and H 3 PO 4 is tribasic.

Polybasic acids dissociate in steps, for example:

From the acid residue H 2 PO 4 formed at the first stage, the subsequent detachment of the H + ion is much more difficult due to the presence of a negative charge on the anion, so the second stage of dissociation is much more difficult than the first. In the third step, the proton must be split off from the HPO 4 2– anion, so the third step proceeds only by 0.001%.

In general, the dissociation of the base can be represented as follows:

where M + is a certain cation.

Such properties of bases as interaction with acids, acid oxides, amphoteric hydroxides and the ability to change the color of indicators are due to the presence of OH - ions in solutions.

The number of hydroxyl groups that are formed during the dissociation of a base is called its acidity. For example, NaOH is a one-acid base, Ba (OH) 2 is a two-acid one, etc.

Polyacid bases dissociate in steps, for example:

Most bases are slightly soluble in water. Water-soluble bases are called alkalis.

The strength of the M-OH bond increases with an increase in the charge of the metal ion and an increase in its radius. Therefore, the strength of the bases formed by elements within the same period decreases with increasing serial number. If the same element forms several bases, then the degree of dissociation decreases with increasing oxidation state of the metal. Therefore, for example, Fe(OH) 2 has a greater degree of basic dissociation than Fe(OH) 3 .

Electrolytes, during the dissociation of which hydrogen cations and hydroxide ions can simultaneously form, are called amphoteric. These include water, hydroxides of zinc, chromium and some other substances. Their full list is given in Lesson 6, and their properties are discussed in Lesson 16.

salts called electrolytes, during the dissociation of which metal cations (as well as the ammonium cation NH 4 +) and anions of acid residues are formed.

The chemical properties of salts will be described in Lesson 18.

Training tasks

1. Electrolytes of medium strength include

1) H3PO4
2) H2SO4
3) Na 2 SO 4
4) Na3PO4

2. Strong electrolytes are

1) KNO 3
2) BaSO4
4) H3PO4
3) H 2 S

3. A sulfate ion is formed in a significant amount during dissociation in an aqueous solution of a substance whose formula is

1) BaSO4
2) PbSO4
3) SrSO4
4) K 2 SO 4

4. When diluting the electrolyte solution, the degree of dissociation

1) stays the same
2) goes down
3) rises

5. The degree of dissociation when a weak electrolyte solution is heated

1) stays the same
2) goes down
3) rises
4) first increases, then decreases

6. Only strong electrolytes are listed in the order:

1) H 3 PO 4, K 2 SO 4, KOH
2) NaOH, HNO 3 , Ba(NO 3) 2
3) K 3 PO 4 , HNO 2 , Ca(OH) 2
4) Na 2 SiO 3, BaSO 4, KCl

7. Aqueous solutions of glucose and potassium sulfate, respectively, are:

1) with strong and weak electrolyte
2) non-electrolyte and strong electrolyte
3) weak and strong electrolyte
4) weak electrolyte and non-electrolyte

8. The degree of dissociation of electrolytes of medium strength

1) more than 0.6
2) more than 0.3
3) lies within 0.03-0.3
4) less than 0.03

9. The degree of dissociation of strong electrolytes

1) more than 0.6
2) more than 0.3
3) lies within 0.03-0.3
4) less than 0.03

10. The degree of dissociation of weak electrolytes

1) more than 0.6
2) more than 0.3
3) lies within 0.03-0.3
4) less than 0.03

11. Both are electrolytes:

1) phosphoric acid and glucose
2) sodium chloride and sodium sulfate
3) fructose and potassium chloride
4) acetone and sodium sulfate

12. In an aqueous solution of phosphoric acid H 3 PO 4, the lowest concentration of particles

1) H3PO4
2) H 2 PO 4 -
3) HPO 4 2–
4) PO 4 3–

13. Electrolytes are arranged in order of increasing degree of dissociation in the series

1) HNO 2, HNO 3, H 2 SO 3
2) H 3 PO 4, H 2 SO 4, HNO 2
3) HCl, HBr, H 2 O

14. Electrolytes are arranged in order of decreasing degree of dissociation in the series

1) HNO 2, H 3 PO 4, H 2 SO 3
2) HNO 3, H 2 SO 4, HCl
3) HCl, H 3 PO 4, H 2 O
4) CH 3 COOH, H 3 PO 4, Na 2 SO 4

15. Almost irreversibly dissociates in aqueous solution

1) acetic acid
2) hydrobromic acid
3) phosphoric acid
4) calcium hydroxide

16. An electrolyte that is stronger than nitrous acid is

1) acetic acid
2) sulfurous acid
3) phosphoric acid
4) sodium hydroxide

17. Stepwise dissociation is characteristic of

1) phosphoric acid
2) hydrochloric acid
3) sodium hydroxide
4) sodium nitrate

18. Only weak electrolytes are presented in the series

1) sodium sulfate and nitric acid
2) acetic acid, hydrosulfide acid
3) sodium sulfate, glucose
4) sodium chloride, acetone

19. Each of the two substances is a strong electrolyte

1) calcium nitrate, sodium phosphate
2) nitric acid, nitrous acid
3) barium hydroxide, sulfurous acid
4) acetic acid, potassium phosphate

20. Both substances are medium strength electrolytes.

1) sodium hydroxide, potassium chloride
2) phosphoric acid, nitrous acid
3) sodium chloride, acetic acid
4) glucose, potassium acetate

Anions are components of double, combined, medium, acidic, basic salts. In qualitative analysis, each of them can be determined using a specific reagent. Let us consider qualitative reactions to anions used in inorganic chemistry.

Analysis features

It is one of the most important options for identifying substances common in inorganic chemistry. There is a division of the analysis into two components: qualitative, quantitative.

All qualitative reactions to anions imply the identification of a substance, the establishment of the presence of certain impurities in it.

Quantitative analysis establishes a clear content of impurities and the base substance.

Specifics of Qualitative Detection of Anions

Not all interactions can be used in qualitative analysis. A reaction is considered characteristic, which leads to a change in the color of the solution, the precipitation of a precipitate, its dissolution, and the release of a gaseous substance.

The anion groups are determined by a selective reaction, due to which only certain anions can be detected in the composition of the mixture.

Sensitivity is the lowest concentration of a solution at which the anion to be determined can be detected without pretreatment.

Group reactions

There are chemicals that can interact with different anions to give similar results. Thanks to the use of a group reagent, it is possible to isolate different groups of anions by precipitating them.

When conducting a chemical analysis of inorganic substances, they mainly study aqueous solutions in which salts are present in a dissociated form.

That is why the anions of salts are determined by their discovery in a solution of a substance.

Analytical groups

In the acid-base method, it is customary to distinguish three analytical groups of anions.

Let us analyze which anions can be determined using certain reagents.

sulfates

For their detection in a mixture of salts in a qualitative analysis, soluble barium salts are used. Considering that sulfate anions are SO4, the short ionic equation for the ongoing reaction is:

Ba 2 + + (SO 4) 2- \u003d BaSO4

The barium sulfate obtained as a result of the interaction has a white color and is an insoluble substance.

Halides

When determining chloride anions in salts, soluble silver salts are used as a reagent, since it is the cation of this noble metal that gives an insoluble white precipitate, therefore chloride anions are determined this way. This is not a complete list of qualitative interactions used in analytical chemistry.

In addition to chlorides, silver salts are also used to detect the presence of iodides and bromides in a mixture. Each of the silver salts that form a compound with a halide has a specific color.

For example, AgI is yellow.

Qualitative reactions to anions of the 1st analytical group

Let us first consider which anions it contains. These are carbonates, sulfates, phosphates.

The most common in analytical chemistry is the reaction for the determination of sulfate ions.

For its implementation, you can use solutions of potassium sulfate, barium chloride. When these compounds are mixed together, a white precipitate of barium sulfate is formed.

In analytical chemistry, a prerequisite is the writing of molecular and ionic equations of those processes that were carried out to identify anions of a certain group.

By writing the full and abbreviated ionic equation for this process, the formation of the insoluble salt BaSO4 (barium sulfate) can be confirmed.

When a carbonate ion is detected in a mixture of salts, a qualitative reaction with inorganic acids is used, accompanied by the release of a gaseous compound - carbon dioxide. In addition, when detecting carbonate in analytical chemistry, the reaction with barium chloride is also used. As a result of ion exchange, a white precipitate of barium carbonate precipitates.

The reduced ionic equation of the process is described by the scheme.

Barium chloride precipitates carbonate ions in the form of a white precipitate, which is used in the qualitative analysis of anions of the first analytical group. Other cations do not give such a result, therefore they are not suitable for determination.

When a carbonate reacts with acids, the short ionic equation is:

2H + +CO 3 - \u003d CO 2 +H 2 O

When detecting phosphate ions in the mixture, a soluble barium salt is also used. Mixing a sodium phosphate solution with barium chloride results in the formation of insoluble barium phosphate.

Thus, we can conclude that barium chloride is universal and can be used to determine anions of the first analytical group.

Qualitative reactions to anions of the second analytical group

Chloride anions can be detected by interaction with a solution of silver nitrate. As a result of ion exchange, a cheesy white precipitate of silver chloride (1) is formed.

The bromide of this metal has a yellowish color, and the iodide has a rich yellow color.

The molecular interaction of sodium chloride with silver nitrate is as follows:

NaCl + AgNO 3 \u003d AgCl + NaNO 3

Among the specific reagents that can be used in the determination of iodide ions in a mixture, we single out copper cations.

KI + CuSO 4 \u003d I 2 + K 2 SO 4 + CuI

This redox process is characterized by the formation of free iodine, which is used in qualitative analysis.

silicate ions

To detect these ions, concentrated mineral acids are used. For example, when concentrated hydrochloric acid is added to sodium silicate, a precipitate of silicic acid is formed, which has a gel-like appearance.

In molecular form, this process:

Na 2 SiO 3 + 2HCl \u003d NaCl + H 2 SiO 3

Hydrolysis

In analytical chemistry, anion hydrolysis is one of the methods for determining the reaction of a medium in salt solutions. In order to correctly determine the variant of the ongoing hydrolysis, it is necessary to find out from which acid and base the salt was obtained.

For example, aluminum sulfide is formed by insoluble aluminum hydroxide and weak hydrosulfide acid. In an aqueous solution of this salt, hydrolysis occurs at the anion and at the cation, so the medium is neutral. None of the indicators will change its color, therefore, it will be difficult to determine the composition of this compound by hydrolysis.

Conclusion

Qualitative reactions, which are used in analytical chemistry to determine anions, make it possible to obtain certain salts in the form of precipitation. Depending on the anions of which analytical group it is necessary to identify, a certain group reagent is selected for the experiment.

It is by this method that the quality of drinking water is determined, revealing whether the quantitative content of anions of chlorine, sulfate, carbonate does not exceed those maximum permissible concentrations that are established by sanitary and hygienic requirements.

In the conditions of a school laboratory, experiments related to the determination of anions are one of the options for research tasks in practical work. During the experiment, schoolchildren not only analyze the colors of the resulting precipitation, but also draw up reaction equations.

In addition, elements of qualitative analysis are offered to graduates in the final tests in chemistry, which allow determining the level of knowledge of future chemists and engineers in molecular, complete and reduced ionic equations.

ANIONS (negative ions) What are anions? How do anions affect the human body?

What are anions?

Molecules and atoms of air, under normal conditions, are neutral. But with the ionization of the air, which can occur through ordinary radiation, microwave radiation, ultraviolet radiation, sometimes simply through a simple lightning strike. The air is discharged - oxygen molecules lose some of the negatively charged electrons revolving around the atomic nucleus, which later find and join any neutral molecules, giving them a negative charge. Such negatively charged molecules are called anions. Man cannot exist without anions, like any other living being.

The aroma of fresh air - we feel the presence of anions in the air of wildlife: high in the mountains, by the sea, immediately after rain - at this time we want to breathe deeply, inhale this purity and freshness of the air. Anions (negatively charged ions) of the air are called air vitamins. Anions treat diseases of the bronchi, the human pulmonary system, are a powerful means of preventing any disease, increase the immunity of the human body. Negative ions (Anions) help purify the air from bacteria, microbes, pathogenic microflora and dust, bringing the number of bacteria and dust particles to a minimum, and sometimes to zero. Anions have a good long-term cleansing and disinfecting effect on the microflora of the surrounding air.

Human health directly depends on the quantitative content of anions in the ambient air. If there are too few anions in the surrounding space in the air that enters the human body, then the person begins to breathe spasmodically, may feel tired, begin to feel dizzy and have a headache, or even become depressed. All these conditions are treatable if the anion content in the air entering the lungs is at least 1200 anions per 1 cubic centimeter. If you increase the content of anions inside residential premises to 1500-1600 anions per 1 cubic centimeter, then the well-being of people living or working there will improve dramatically; You will begin to feel very good, work with redoubled energy, thereby increasing your productivity and the quality of work.

With direct contact of anions with the skin, due to the high penetrating ability of negative ions, complex biochemical reactions and processes occur in the human body, which contribute to:

general strengthening of the human body, immunity and maintaining the energy status of the body as a whole

improvement of blood supply to all organs, improvement of brain activity, prevention of oxygen deficiency of the brain,

Anions improve the functioning of the heart muscle, kidney and liver tissues

anions enhance blood microcirculation in the vessels, increase tissue elasticity

negatively charged particles (anions) prevent aging of the body

anions contribute to the activation of anti-edematous and immunomodulatory effects

anions help against cancer, tumors, increase the body's own antitumor defenses

with an increase in anions in the air, the conductivity of nerve impulses improves

Thus follows:

Anions (negative ions) are an indispensable assistant in strengthening human health and prolonging his life

Classification of cations and anions.

Analysis methods.

Analytical chemistry is the science of determining the chemical composition of a substance.

Analytical chemistry and its methods are widely used in catering and food industries to control the quality of raw materials, semi-finished products, finished products; determination of the terms of sale and storage conditions of products.

In analytical chemistry, there are quantitative and qualitative analysis. Task quantitative analysis- determination of the relative amount of elements in compounds or chemical compounds in mixtures; task qualitative analysis- detect the presence of elements in compounds or chemical compounds in mixtures.

History of development of analytical chemistry.

Initially with the help qualitative analysis determined the properties of certain minerals. To quantitative analysis was used in the assay business (determination of precious metals) - Ancient Greece, Egypt. In the 9th-10th century, assay methods were used to determine precious metals in Kievan Rus.

Analytical chemistry as a science begins to develop from the middle of the 17th century.

For the first time, the foundations of qualitative analysis were outlined by the English scientist R. Boyle, who also introduced the term "chemical analysis". R. Boyle is considered the founder of scientific analytical chemistry.

The laws of quantitative analysis were outlined by Lomonosov in the middle of the 17th century. Lomonosov was the first to use the weighing of starting materials and reaction products.

By the middle of the 19th century, titrimetric and gravimetric methods of analysis, as well as methods of gas analysis, took shape.

The first textbook on analytical chemistry appeared in Russia in 1871. The author of this textbook is the Russian chemist N.A. Menshutkin.

In the second half of the 20th century, many new methods of analysis appeared: X-ray, mass spectral, etc.

Classification of methods of analysis used in analytical chemistry.

Analytical chemistry includes two main sections: quantitative analysis and qualitative analysis.

Qualitative analysis methods:

Ø Chemical

Ø Physical and chemical

Ø Physical

Chemical analysis:

Ø "dry" way

Ø "wet" way

"Dry" path - chemical reactions that occur during incandescence, fusion, coloring of the flame.

Example : coloring of the flame with metal cations (sodium - yellow, potassium - pink-violet, calcium - orange-red, copper - green, etc.), which are formed during the electrolytic dissociation of salts:

NaCl → Na++Cl-

K2CO3 → 2K+ + CO 3 2-

"Wet" way - chemical reactions in electrolyte solutions.

Also, in a qualitative analysis, depending on the amount of the test substance, the volume of the solution, and the execution technique, there are:

1) macromethod: relatively large portions (0.1 g or more) or large volumes of solutions (10 ml or more) of the test substance. This method is the most convenient to define.

2) micromethod: samples from 10 to 50 mg and solution volumes up to several ml.

3) semi-micro method: weighing 1-10 mg and solution volumes of about 0.1-1 ml.

The micromethod and the semimicromethod have two undoubted advantages:

1. High speed analysis

2. Small amount of analyte required.

Physical and chemical methods of analysis:

Ø colorimetric (comparison of the color of two solutions)

Ø nephelometric (turbidity of the test solution from the action of some reagents)

Ø electrochemical (the moment of the end of the reaction is determined by the change in the electrical conductivity of the solution, the potential of the electrodes in the test solution)

Ø refractometric (determine the refractive index)

Physical methods of analysis:

Ø spectral analysis (study of emission or absorption spectra)

Ø luminescent (studying the nature of the luminescence of a substance under the action of UV)

Ø mass spectrometric

Ø refractometric

Analytical reactions are used to detect ions in solutions in analytical chemistry.

An analytical reaction is a chemical transformation in which the substance under investigation is converted into a new compound with a characteristic feature.

Signs of an analytical reaction:

Ø Precipitation

Ø Sediment dissolution

Ø Color change

Ø Emission of gaseous substance

Analytical reaction conditions:

Ø Fast flow

Ø Specificity

Ø Sensitivity

A sensitive reaction is a reaction that can detect the smallest amount of a substance from the smallest amount of a solution.

Sensitive reaction is characterized by:

1. Opening low(the smallest amount of a substance that can be detected by a given reaction)

2. Minimum concentration(the ratio of the mass of the analyte to the mass or volume of the solvent).

A specific reaction is a reaction by which an ion can be opened in the presence of other ions by a specific color change, the formation of a characteristic precipitate, gas evolution, etc.

Example: the barium ion is detected with potassium chromate K 2 CrO 4 (a bright yellow precipitate forms).

Analysis is based on specific reactions, called fractional. Using fractional analysis, you can open ions in any sequence using specific reactions.

However, few specific reactions are known; more often, reagents interact with several ions. Such reactions and reagents are called general. In this case apply systematic analysis. Systematic analysis- a certain sequence of detection of ions in the mixture. The ions that make up the mixture are divided into separate groups, from these groups each ion is isolated in a strictly defined sequence, and then this ion is opened by the most characteristic reaction. Reactions characteristic of a single ion are called private.

Classification of cations and anions.

The classification of ions in analytical chemistry is based on the difference in the solubility of the salts and hydroxides they form.

Analytical group - a group of cations or anions, which with any one reagent gives similar analytical reactions.

Cation classifications:

Ø sulfide, or hydrogen sulfide, is a classic, developed by Menshutkin N.A.;

Ø acid-base, etc.

The sulfide classification of cations is based on the ratio of cations to sulfide ion:

1) Cations precipitated by sulfide ion

2) Cations not precipitated by the sulfide ion.

Each group has its own group reagent- a reagent used to open one group of ions and form a precipitate with ions of this group (Ва 2+ + SO 4 2- → ВаSO 4 ↓)

Determination of cations is carried out systematic analysis.

Cations and anions perform important functions in the body, for example:

Responsible for the osmolality of body fluids

Form a bioelectric membrane potential,

Catalyze the metabolic process

Determine the actual reaction (pH) of the body fluid,

Stabilize certain tissues (bone tissue),

Serve as an energy depot (phosphates),

Participate in the blood coagulation system.

A 70 kg human body contains approximately 100 g of sodium (60 meq/kg), 67% of which is actively exchanged (Geigy). Half of the body's sodium is in the extracellular space. A third is located in the bones and cartilage. The content of sodium in cells is low (see also Fig. 6).

Plasma concentration: 142(137-147) meq/l

Main role

Mainly responsible for the osmolality of the extracellular space. 92% of all cations and 46% of all extracellular osmotically active particles are sodium ions.

The sodium concentration can determine plasma osmolality, with the exception of such pathological processes as diabetes mellitus, uremia (see 1.1.2).

The amount of extracellular space depends on the sodium content.

With salt-free diets or the use of saluretics, the extracellular space decreases; it increases with increased sodium intake.

Influence on the intracellular space through the content of sodium in the plasma. With an increase in extracellular osmolality, for example, with the introduction of a hypertonic saline solution, water is removed from the cells, with a decrease in plasma osmolality, for example, with loss of salt, the cells are flooded.

Participation in the creation of bioelectric membrane potential. Potassium

The human body weighing 70 kg contains approximately 150 g of potassium (54 mEq / kg), 90% of it is actively involved in the exchange (Geigy); 98% of the body's potassium is in the cells and 2% is extracellular (Fleischer, Frohlich). In the muscles, 70% of the total potassium content (Black) is determined.

The concentration of potassium is not the same in all cells. Muscle cells contain 160 meq potassium/kg water (Geigy), erythrocytes have only 87 meq/kg red blood cells (Burck, 1970).

Plasma potassium concentration: 4.5 (3.8-4.7) meq 1 liter.

Main role

Participates in the utilization of carbohydrates;

Essential for protein synthesis; during the breakdown of proteins, potassium

freed up; binds during synthesis (ratio: 1 g of nitrogen to approximately 3 meq of potassium);

It has an important effect on neuromuscular excitation.

Each muscle cell and nerve fiber at rest is a potassium battery, the charge of which is largely determined by the ratio of potassium concentrations inside and outside the cells. The excitation process is associated with the active inclusion of extracellular sodium ions in the internal fibers and the slow release of intracellular potassium from the fibers.

The drugs cause the withdrawal of intracellular potassium. Conditions associated with low potassium content are accompanied by a pronounced effect of digitalis preparations. In chronic potassium deficiency, tubular reabsorption is impaired (Nizet).

Potassium is involved in the activity of muscles, heart, nervous system, kidneys, every cell.

Peculiarities

Of great practical interest is the relationship between plasma potassium concentration and intracellular potassium content. There is a principle that with a balanced metabolism, the content of potassium in the plasma determines its total content in the whole body. This ratio is affected by:

The pH value of the extracellular fluid,

The energy of metabolism in the cell,

Kidney function.

Effect of pH value on plasma potassium concentration

With a normal content of potassium in the body, a decrease in pH increases the amount of potassium in the plasma, (an increase in pH - decreases. Example: pH 7.3, acidemia - plasma potassium concentration 4.8 meq / l pH 7.4, normal - plasma potassium concentration 4.5 mEq/L pH 7.5, Alkalemia-Plasma Potassium Concentration 4.2 mEq/L (Values ​​calculated from Siggaard-Andersen, 1965.) , the value of 4.5 mEq / l of plasma indicates an intracellular potassium deficiency in acidemia.On the contrary, in case of alkalemia in the case of a normal content of potassium, one should expect a reduced content of it in plasma.Knowing the acid-base state, one can better estimate the amount of potassium in the plasma:

Acidemia → [K] plasma - increase Alkalemia → [K] plasma - decrease

These dependences, revealed in the experiment, are not always clinically proven, since they simultaneously develop: further processes that affect the amount of potassium in the plasma, as a result of which the effect of one process is leveled (Heine, Quoss, Guttler).

Influence of cell metabolic energy on plasma potassium concentration

An increased outflow of cellular potassium into the extracellular space occurs, for example, when:

Insufficient supply of oxygen to tissues (shock),

Increased protein breakdown (catabolic state).

Reduced utilization of carbohydrates (diabetes),

Cellular dehydration.

An intensive influx of potassium into cells is observed, for example, when:

Improved glucose utilization under the action of insulin,

Increased protein synthesis (growth, administration of anabolic steroids, repair phase after surgery, trauma),

Cellular rehydration.

Destructive processes →[K]plasma - increase Restorative processes →[K]plasma - decrease

Sodium ions, introduced in large quantities, increase the exchange of cellular potassium and contribute to increased excretion of potassium through the kidneys (especially if sodium ions are associated not with chloride ions, but with easily metabolized anions, such as citrate). The concentration of potassium in plasma due to excess sodium decreases as a result of an increase in extracellular space. A decrease in sodium leads to a decrease in the extracellular space and an increase in the concentration of potassium in the plasma:

Excess sodium → [K] plasma - decrease Sodium deficiency → [K] plasma - increase

Influence of the kidneys on the concentration of potassium in plasma

The kidneys have less influence on the maintenance of potassium than sodium. With a lack of potassium, the kidneys retain it at first with difficulty, so the losses may exceed the introduction. On the contrary, in case of an overdose, potassium is quite easily removed by the flow of urine. With oliguria and anuria, the amount of potassium in the plasma increases.

Oliguria, anuria → [K] plasma - increased

Thus, the extracellular (plasma) concentration of potassium is the result of a dynamic balance between:

Introduction;

The ability of cells to retain depending on the pH value and the state of metabolism (anabolism - catabolism);

Renal excretion of potassium depending on:

acid-base condition

flow of urine

aldosterone;

Extrarenal loss of potassium, for example, in the gastrointestinal tract. Calcium

An adult weighing 70 kg contains approximately 1000-1500 g of calcium - from 50,000 to 75,000 meq (1.4-2% of body weight), 99% of calcium is in the bones and teeth (Rapoport).

Plasma concentration: 5 (4.5-5.5) meq / l with small individual deviations (Rapoport).

Plasma calcium is distributed in three fractions, namely 50-60% is ionized and diffusible, 35-50% is associated with proteins (not ionized and not diffusible), 5-10% is complexed with organic acids (citric acid ) - not ionized, but capable of diffusion (Geigy). Between individual fractions of calcium there is a mobile equilibrium, which depends on pH. In acidosis, for example, the degree of dissociation, and, consequently, the amount of dissociated calcium increases (slows down the effects of tetany in acidosis).

Only calcium ions are biologically active. Precise data to determine the state of calcium metabolism is obtained only by measuring the amount of ionized calcium (Pfoedte, Ponsold).

Main role

Component of bones. Calcium in the bones is in the form of an insoluble structural mineral, mainly calcium phosphate (hydroxyapatite).

Influence on the excitability of nerves and muscles. Calcium ions mediate the bioelectrical phenomenon between the surface of the fibers and the contractile reactions within the fibers.

Influence on membrane permeability.

Contribution to the blood coagulation system.

Peculiarities

The absorption of calcium in the intestine is affected by the composition of food. So, calcium absorption is promoted by citric acid and vitamin D, and organic acids, such as oxalic acid (spinach, rhubarb), phytic acid (bread, cereals), fatty acids (gallbladder diseases) prevent calcium absorption. The optimal ratio of calcium and phosphate (1.2.1) promotes absorption. Parathyroid hormone, vitamin D and calcitonin play a leading role in the regulation of calcium content.

In a human body weighing 70 kg is 20-28 g of magnesium (Hanze) - from 1600 to 2300 mEq. It is determined predominantly in the skeleton (half of the total), less in the kidneys, liver, thyroid gland, muscles and nervous system (Simon). Magnesium, along with potassium, is the most important cation of animal and plant cells.

Plasma concentration: 1.6-2.3 meq/l (Hanze).

Approximately 55-60% of plasma magnesium is ionized, 30% is bound to proteins and 15% to complex compounds (Geigy).

Main role

Significance for numerous enzyme-driven processes

(cell regeneration, oxygen utilization and energy release; Simon). Magnesium is important for glycolysis, various steps of the citrate cycle, oxidative phosphorylation, phosphate activation, nucleases, various peptidases (Hanze).

It inhibits the transfer of nervous excitation to the end point (like curare; the antagonist is calcium ions), resulting in a decrease in neuromuscular excitation.

Depressive effect on the central nervous system.

Decreased contractility of smooth muscles and myocardium.

Suppression of excitation in the sinus node and impaired atrioventricular conduction (at very high doses, cardiac arrest in diastole).

Vasodilation.

Promoting fibrinolysis (Hackethal, Bierstedt).

Peculiarities

Along with absorption and excretion through the kidneys, the pancreatic hormone, which has not yet been fully studied, is involved in the regulation of magnesium content in the body. Magnesium deficiency leads to the removal of magnesium and calcium ions from the bones. Absorption is lowered by foods rich in protein and calcium, and also by alcohol (Simon).

A human body weighing 70 kg contains approximately 100 g of chlorine - 2800 mEq (Rapoport). Plasma concentration: 103 (97-108) meq/l

Main role

Chlorine is the most important part of plasma anions.

Chlorine ions are involved in the formation of the membrane potential.

Bicarbonate

Bicarbonate refers to the variable part of the ions. Changes in anion content are balanced by bicarbonate. The bicarbonate - carbonic acid system is the most important extracellular buffer system. The pH value of the extracellular space can be calculated from the ratio of bicarbonate to carbonic acid (see 1.3 for further discussion).

The body of an adult contains 500-800 g of phosphate (1% of body weight). 88% are in the skeleton (Grossmann), the rest is located intracellularly and only a small part of it is in the extracellular space (Rapoport).

Phosphate can be either organic (as a component of phosphoproteins, nucleic acids, phosphatides, coenzymes - Rapoport) or inorganic. Approximately 12% of plasma phosphate is protein bound.

Plasma concentration (inorganic phosphorus): 1.4-2.6 meq / l.

Main role

Together with calcium, it forms insoluble hydroxylapatite (the supporting function of bones).

Participation in the metabolism of carbohydrates, as well as in the storage and transfer of energy (ATP, creatine phosphate).

buffer action.

Peculiarities

Phosphorus is found in all foods. Absorption is stimulated by vitamin D and citrate, delayed by certain metals (eg aluminum), cyanides, and increased calcium intake. Phosphates excreted in the urine act as a buffer.

Plasma concentration (inorganic sulfate): 0.65 meq/l

Sulfate is formed from sulfur-containing amino acids (eg, cysteine, methionine) and excreted through the kidneys.

In renal insufficiency, the concentration of sulfates in plasma increases by 15-20 times.

Organic acid radicals

Lactate (lactic acid).

Pyruvate (pyruvic acid).

Beta-hydroxybutyrate (beta-hydroxybutyric acid).

Acetoacetate (acetoacetic acid).

Succinate (succinic acid).

Citrate (citric acid).

Plasma concentration: 6 mEq/L (Geigy)

Lactic acid is an intermediate product in the process of carbohydrate metabolism. With a decrease in oxygen levels (shock, heart failure), the concentration of lactic acid rises.

Acetoacetic acid and beta-hydroxybutyric acid (ketone bodies) appear with a decrease in the amount of carbohydrates (hunger, fasting), as well as with impaired carbohydrate utilization (diabetes) (see 3.10.3).

Protein molecules at a blood pH of 7.4 exist mainly in the form of anions (16 meq/l of plasma).

Main role

Life is connected with proteins, hence without proteins there is no life Squirrels

They are the main component of cellular and interstitial structures;

Accelerate metabolic processes as enzymes;

They form the intercellular substance of the skin, bones and cartilage;

Provide muscle activity due to the contractile properties of certain proteins;

Determine the colloid osmotic pressure and thus the water-holding capacity of the plasma (1 g of albumin binds 16 g of water);

They are protective substances (antibodies) and hormones (for example, insulin);

Transport substances (oxygen, fatty acids, hormones, medicinal substances, etc.);

Act as a buffer;

Participate in blood clotting.

This enumeration already shows the fundamental importance of proteins.

Protein balance is particularly stressed under stress (see also 3.8.2.1).

Clinician Instructions

When determining the state of proteins, the following parameters are usually involved:

Clinical assessment of the patient's condition (weight loss, etc.);

The concentration of total protein and albumin in plasma;

Transferrin concentration;

The state of immunity (for example, skin test, examination with BCG, etc., determination of the number of lymphocytes, etc.).

A sensitive indicator of the state of protein nutrition, which is the concentration of albumin in plasma, represents the amount of extravascular storage of albumin, measured using labeled albumin. Extravascular, interstitial albumin can be considered as a protein reserve. It rises with excellent nutrition and decreases with protein deficiency without altering plasma albumin concentration (Kudlicka et al.).

The intravascular reserve of albumin is 120 g, interstitial - from 60 to 400 g, in adults, on average 200 g. When the concentration of albumin in the plasma falls below the limit of the norm, the interstitial reserves of albumin are significantly depleted in the first place (Kudlicka, Kudlickova), as can be seen from Table . 2 and 3. In 46 patients operated on for chronic gastroduodenal ulcers, Studley correlated postoperative mortality with preoperative weight loss (see Table 3).

table 2

Lethality depending on the concentration of serum albumin in the clinical material of therapeutic patients (Wuhmann, Marki)