Hypotonic, hypertonic and isotonic solutions. Isotonic, hypertonic and hypotonic solutions and their role in the body Use for ENT diseases

The loss of fluid in the body is called dehydration, or dehydration. Dehydration can be physiological (sweating) or pathological (diarrhea, bleeding, etc.). Replenishment of fluid volume is called rehydration, and can be carried out urgently by intravenous administration large volumes different solutions, blood and blood plasma, and also gradually by taking liquids orally. Other routes of fluid administration are less common.
Many sources say that during a cold, especially accompanied high temperature body, must be taken a large number of liquids. But this is not an entirely accurate statement, and against the background of the body’s fight against infection, a large water (liquid) load can be harmful.

Things to remember before you start additional dose liquids? A few basics of water-salt metabolism, which will be discussed further.
You will be absolutely right if you remember the well-known postulate that the human body consists of 75-80% water, but this amount of water is only found in newborns and small children. The adult human body contains 60 to 65% (men) and 50 to 60% (women) water. At older ages, the percentage of water decreases slightly. About 85% of the brain is made up of fluid, and bone tissue there is only 10-15% water.

Of all the water contained in the body, 60% of it is inside the cells (in the cytoplasm and nucleus), the rest is outside the cells (extracellular). In the blood vessels and lymphatic vessels there is about 20% remaining fluid, and the remaining 80% is gastrointestinal fluid and interstitial fluid.
The cell membrane, like cells, is not water-soluble, but at the same time, no substance can penetrate the cell unless it is dissolved in water and is not in the form of ions. Row organic matter for assimilation, they require connection with special carrier proteins, as well as the presence of enzymes (enzymes).

In reality, there is no pure water in the human body. We are all, without exception, reservoirs of saline solutions. The presence of salt ions and a number of other substances (carbohydrates, fats and proteins) creates a certain acid-base environment, as well as a specific pressure, which is called osmotic pressure. Osmotic pressure plays important role in the exchange of salt ions (electrolytes) through the cell wall, and all life processes of the body are based on it.
Osmosis characterizes the penetration of water through membranes. If a cell is placed in clean water, water molecules will begin to penetrate into the cell, since there is a certain concentration of salts in the cell cytoplasm. In this case, the cell increases in size (swells, swells) and may even die. Absorption of water is a necessary life process (for example, by plant roots from the soil).
On the contrary, if a cell is placed in a solution whose concentration of salt ions is higher than the intracellular concentration, the cell will begin to lose its fluid, that is, shrink in size, because water molecules will begin to leave the cell first.

Probably many of you have heard the word “ isotonic", especially if you had to be treated in a hospital. Isotonic solutions are used for intravenous drips, when it is necessary to administer a large amount of liquid or when the drug must be administered in low concentrations and for a long period of time, as well as for different injections.
The term “isotonic” refers to “tone,” that is, the osmotic pressure that occurs when there are different concentrations of solutions outside and inside the cell. Moreover, osmotic pressure depends not on the type of substance, but on its concentration. "Isotonic" means almost the same osmotic pressure across different sides cell membrane, when there is practically no exchange of water through it or it is in a balanced state. In this case, the cell becomes “open” to ions of minerals and other substances.
The closer the solutions are isotonic, including through the mouth, the better they are perceived by the human body, which constantly compares all substances on the “self-foreign” scale, and therefore with less aggression.

A saline solution of sodium chloride or glucose has almost the same osmotic pressure as human blood and intracellular fluid, and therefore does not cause cell destruction. It quickly replenishes fluid volume in the body without seriously affecting water-electrolyte metabolism. Simultaneously, through isotonic solutions Medicines can be administered, the absorption of which is significantly improved.
Hypertonic solution implies a greater concentration of substances, which means greater osmotic pressure on the cell membrane, therefore, when such solutions are introduced, the cells will begin to lose their own (cytoplasmic) fluid.

Hypotonic solution means a lower concentration, which means lower osmotic pressure outside the cells, so water molecules will be the first to penetrate into the cell from such solutions.

The figure shows the influence different types solutions on the condition of red blood cells. Therefore, when introducing medicinal substances, especially intravenously, their osmolarity must be taken into account.

Now we've come To a question water regime . In some sources you will find a statement that to maintain health you need to drink at least 8 glasses of water (up to 2 liters of water) per day, but this statement is based only on theoretical assumptions and not on scientific facts.
With food you get up to 1 liter of water. Your body produces 600-700 ml of water as a result of chemical reactions. The body can excrete up to 2-2.5 liters of water in different ways. Losing water through the skin (sweating) and respiratory system(breathing) largely depends on your physical activity. The less you move, the less fluid you lose. Therefore, additional load on the body with water due to a sedentary lifestyle (which many older people suffer from) can lead to negative reaction– heavy load on the urinary and cardiovascular system. Water poisoning is quite possible, but few people talk about it.

Let's remember the features of water exchange. Animals drink water only when they feel thirsty, since in the animal world many processes are rational and closely related to self-preservation instincts. The same can be said about flora: Fill a flower pot with water, you will kill it rather than help it, because the plant will only absorb the amount of water it needs. The feeling of thirst is the best indicator of whether a person needs fluid or not.
When water enters the body, it is not absorbed immediately, that is, even if the body is seriously dehydrated, it will not be saturated with water in a matter of minutes or even hours. Water is primarily involved in the human body(the very first link of its use) in body temperature exchange. If the body overheats, excess energy is released through the process of sweating and the body cools down. Therefore, when you are engaged in physical activity or your metabolism is increased (for example, with hyperfunction thyroid gland), you begin to sweat, losing body fluid, but along with it a number of salts.
When you sweat, you rarely urinate because your body is already losing water through skin. On the contrary, when you are cold, the body tries to get rid of excess water; heating the “water reservoir” requires a lot of energy, so in cold weather you urinate more often. The absorption of water in the gastrointestinal tract, mainly in the large intestine, occurs at a certain speed and in a certain volume, so excess water is excreted through the intestines, kidneys and skin. By the way, drinking water reduces appetite.

Water is necessary for human body . Some nutritionists advise not to wait until you feel thirsty, because supposedly you can wait until you become seriously dehydrated. This is not an entirely accurate statement. The feeling of thirst appears when you lose from 0 to 2% of the total volume of body water, and at 2% you feel very thirsty! Symptoms of dehydration (weakness, fatigue, apathy, loss of appetite, difficulty performing physical activity) appear when a person loses 4% or more of body water volume. Thus, the feeling of thirst (not extreme thirst) is indeed one of the best indicators that our body needs fluid (not just water).
In children and older people, the process of water exchange and water-electrolyte imbalance are observed more often, although rehydration occurs much faster in children than in adults.
In children, the pathological loss of water and salts also passes faster, since their brain center that regulates water-salt and temperature metabolism is still in a state of maturation (therefore, an “unreasonable” short-term increase in body temperature in young children is a common occurrence). Given that children's bodies are "waterier", they need regular replenishment of water supplies.
Many parents complain that their children almost constantly ask for something to drink, especially during physical activity or during hot weather. In such cases, it is important not to give sweet drinks, which, due to the presence of sugar, lead to loss of water in the mucosal cells oral cavity(simply “dried”), and therefore provoke a feeling of thirst even more.
But it’s one thing to be healthy, it’s another thing when conditions arise that require restoration of fluid volume and water-salt balance. Under what circumstances is there a rapid loss of water, and with it salts? This is the loss of blood and/or plasma as a result of bleeding, after extensive burns, due to diarrhea and vomiting due to various reasons(infection, poisoning), as a result of an overdose of diuretics. In other words, any rapid loss of a large amount of fluids leads to an imbalance of water-salt balance.
In addition to diseases, dehydration is observed as a result of profuse sweating, which occurs during intense physical activity, overheating, presence elevated temperature body (fever), as well as diseases of the thyroid gland.

How to restore water supplies, that is, to carry out rehydration? Need to understand important fact: against the background of a disease that often debilitates the body, sudden volumetric administration of fluid can lead to an even greater deterioration of the condition, so there must be a measure in everything, including the amount of fluid! Fluid intake begins with sips small amount water, increasing the frequency of intake. It is very important to monitor urination, which should be observed every 2-3 hours, or even more often. If a person does not urinate for 5-6 hours, it is impossible to load him with excess water and liquids. Therefore, the first 4-6 hours are control periods in terms of the amount of fluid administered and require taking small doses of water, but frequently.

What types of liquids should be preferred?? Here it is important to return again to the concept of isotonicity, hypertonicity and hypotonicity. Since the fluid is introduced through gastrointestinal tract, the mucous membranes of the organs will be the first to come into contact with water molecules digestive system. With vomiting and diarrhea, water and salts are already removed from the cells to the outside, which means the cells and tissues are dehydrated. That's why the best option there will be isotonic saline solutions or slightly hypotonic (low osmolarity) solutions.

Why should you not use concentrated saline solutions?, that is, hypertensive? Because this will lead to even greater loss of intracellular water. If hypotonic solutions are administered, they can also lead to rapid tissue swelling.

Regidron, which is somehow forgotten or ignored by doctors, is saline preparation with slightly reduced osmolarity. By dissolving the contents of the sachet in the required amount of water (usually 1 liter), a solution is obtained that replenishes the intracellular loss of water not harshly, but at the same time quickly, due to its hypotonicity.

Why do many salt and other combinations of drugs for restoring electrolyte-water balance include sugars?(glucose, fructose, lactose) in small quantities? To maintain the equilibrium of the solution and maintain its osmolarity for a certain period of time (usually several hours).
Blood plasma osmolarity is 280-300 mOsm/l and pH 7.37-7.44. Regidron has an osmolarity of 260 mOsm/l and a pH of 8.2, which differs slightly from the properties of human fluids, and at the same time promotes the transport of water and salt ions through cell membranes.
Taking large amounts of juices to restore water-salt balance is not recommended, despite the fact that these are liquids, and as many people think, they contain vitamins and minerals and are therefore beneficial. Most juices are not 100% natural product, since they are created from a concentrate diluted in water and contain a large number of additives: sugar, dyes, flavors, etc. To obtain an “isotonic solution” of juice or something close to it, 1 liter of water must contain 50 g of glucose.
1 liter of different juices may contain different amounts of sugar. For example, 1 l carrot juice contains 40 g of sugar, orange juice - 90-100 g (in fresh juice from oranges – 100-120 g sugar), fruit drinks – 100-110 g, apple juice– 120 g, cranberry juice – 120-130 g, grape juice – 150 g, grapefruit juice – 90 g sugar. 1 liter of most canned juices contains 120-150 g of sugar. Many manufacturers add more sugars to juices to increase shelf life.
Thus, most juices are hypertonic solutions and can aggravate dehydration. Doctors often recommend diluting juices half with water, especially for children.
Teas, including herbal ones, are hypotonic and hyposmolar unless sugar or honey is added. But, like coffee, teas can contain caffeine and tannin, which in small quantities are beneficial for the body, but against the background of its dehydration, and in large quantities can be harmful, disrupting protein metabolism and causing intoxication. Tannin is also found in a number of fruit drinks.

Row medicinal herbs when the body is weakened and in a state of dehydration, they can have a toxic effect, therefore herbal teas must be taken with great caution.
While sugar can be dosed in teaspoons, the dosage of honey, especially the amount of sugars it contains, is extremely difficult, so it should not be used in cases of dehydration.

How about lean chicken broth?, which is recommended for sick people, especially those who are weakened and dehydrated? Broth is nothing more than an aqueous solution of salts, proteins, a small amount of fats and other substances. Many experimenters have conducted studies on the broth's healthiness, taking into account osmolarity and pH.
Naturally, the most natural option would be a broth whose pH is close to 7.0-8.0. But none of the housewives will take such measurements. However, by connecting folk wisdom cooking with the results of “broth” experiments, as well as with the wisdom traditional medicine, certain conclusions can be drawn.
If you prepare broth from red meat (legs), it is more acidic (i.e. its pH is 5.0-5.8), so preference should be given to white meat (breast). The more transparent and lighter in color the broth, the more beneficial it is for absorption. In 1 liter of broth there should be no more than 2 teaspoons of salt (without top), i.e. no more than 10 g. A smaller amount of salt is acceptable, but you should not give up salt completely.
How much meat and water is needed? The issue is controversial, but usually one brisket per 3 liters of water is enough. It is important to remember that the broth should be transparent and not too rich in color. Also, the process of preparing the broth should not be lengthy, i.e. no more than 2 hours on low heat. The more the broth is cooked, the more its pH shifts towards acidity due to the breakdown of proteins, although more flavor appears.
Some seasonings and additives may change acid-base balance broth (usually those found in dry seasonings, such as Vegeta, are alkalized, because soda is often included in it). It is important to consume the broth warm (not hot) immediately after cooking. The optimal period for taking the broth is the cessation of diarrhea and the absence of fever.

Also healing properties has milk, the pH of which is very close to the intracellular fluid. Therefore, it is not surprising that milk was given to people exhausted by illness, since it is easily digested by most consumers and contains a large number of useful ingredients.

Thus, the best option for replenishing liquids and salts in a number of conditions would be to take ready-made saline solutions, less often solutions of glucose and ordinary water. A combination of different types of fluids is possible after signs of dehydration disappear and during recovery.

In this article: a description of a hypertonic solution, what it is, why the solution is called that, its types. Mechanism of action various pathologies how and when you can make the solution yourself and apply it.

Article publication date: 04/07/2017

Article updated date: 05/29/2019

A hypertonic salt solution (sodium chloride) is a liquid with a concentration of the main substance above 0.9%. To understand where the name “hypertonic” comes from, it is necessary to understand the basics of the normal physiology of the cell and the substance surrounding it.

Liquid is the main part of the contents of the cell and the space surrounding it; all substances necessary to maintain normal function are dissolved in it. The exchange of contents occurs based on the difference in liquid pressure. IN physiological conditions normal pressure fluid in cells and intercellular substance is maintained by sodium chloride ions at a concentration of 0.9%, the same percentage in human blood plasma. If the amount of substance inside and outside the cell is equal, there is no transition of ions; when it changes, the ions move in the direction with a lower concentration, maintaining equilibrium. Thus, a 0.9% solution of sodium chloride or salt is called physiological or isotonic (relative to blood plasma), and any solution of higher concentration is called hypertonic.

This solution is an official drug widely used in medical practice in different concentrations:

1–2% for rinsing, washing the nasal passages and throat (otolaryngology);
2–5% for gastric lavage (emergency medicine);
5–10% for treatment infected wounds(purulent surgery), as well as to stimulate the passage of stool during constipation (therapy, postoperative period);
10% for treatment and in case of urinary obstruction (emergency and emergency medicine).

Taking into account the indications, the solution can be recommended or prescribed for treatment and prevention by doctors of several specialties: therapists, otorhinolaryngologists, surgeons, resuscitators, nephrologists.

Indications for use and mechanism of action

Depending on the type pathological process and method of administration, different concentrations of the drug are used. Some methods of use require only a pharmaceutical (sterile) form medicine, suitable for others self-cooking. Before moving on to home recipes, you need to consider in detail how and what medicine to use.

1–2% salt solution

Indications: infectious and inflammatory diseases of the mucous membranes of the nasal passages, maxillary sinuses, oral cavity (rhinitis, sinusitis, tonsillitis, pharyngitis, stomatitis), as well as - surgical interventions and injuries in this area.

Action: inhibits the growth of microorganisms, reduces tissue swelling and pain.

Application: rinse your nose or gargle your mouth and throat every 4 hours acute period diseases. Duration of use is 3–5 days depending on clinical manifestations.

2–5% salt solution

Indications: gastric lavage if lapis (silver nitrate) is ingested.

Action: by entering into a chemical reaction, a hypertonic salt solution neutralizes the acid by forming safe silver chloride, which is excreted unchanged through the intestines.

Application: use in the first minutes after ingestion of lapis, if the victim cannot drink on his own, administer through a gastric tube. Total volume up to 500 ml depending on the amount of silver nitrate ingested.

5–10% salt solution

Indications:

infected wounds with copious purulent discharge;
prolonged absence of stool, including after surgical treatment abdominal organs.

Action:

has a pronounced antimicrobial effect, reduces swelling and inflammation in the purulent focus, reduces pain;
in the ampoule of the rectum, the solution irritates the mucous membrane and increases the release of fluid into the lumen, softening feces and stimulating bowel movements.

Application:

dressings with napkins generously soaked in the drug 2-3 times a day (the frequency depends on the severity of purulent-inflammatory changes);
microenemas (total volume up to 200 ml) 1–2 times in the morning.

10% salt solution

Indications:

internal and external bleeding with a large volume of blood loss;
acute renal failure stage sharp decline or complete absence urine excretion by the kidneys (oligo- and anuria).

Action:

increases the volume of blood plasma by stimulating the release of fluid from the intercellular space into the vessels;
restoration of the lack of sodium and chlorine ions against the background of disturbed water and electrolyte balance.

Application: slow, intravenous administration with a total volume of up to 10–20 ml.

Contraindications and negative effects

Hypertonic solution - universal medical product with a minimum number of contraindications:

Contraindication for local application(washing, rinsing, dressings, microenemas) – individual intolerance ( allergic reactions any type).

Contraindications for intravenous administration:

individual intolerance;
in the absence of urine output - only according to strict laboratory indications (decreased chlorine and sodium ions in the blood plasma and increased potassium content);
for large blood losses, they are currently rarely used - only if there is a shortage of drugs to restore the volume of circulating plasma (due to the need to administer large volumes of solution to adequately support heart function and blood circulation, which in turn leads to electrolyte disturbances, aggravating the patient’s condition ).

Burning or even slight pain in the area of the wound surface when applying a napkin with a solution - normal reaction and does not require its cancellation. Unpleasant sensations disappear with regular use.

Administration of the drug subcutaneously and intramuscularly is absolutely contraindicated - tissue necrosis develops at the injection site.

Administration of a large volume of solution through the stomach or intravenously will lead to the development of hypernatrium and hyperchloremia (exceeding the physiological concentration of ions in the blood). Clinical manifestations include: thirst, impaired consciousness, convulsions. In extreme cases, coma and cerebral bleeding develop.

Self-cooking

For use for the purpose of washing the mucous membranes of the nasal passages, mouth, throat, stimulating the passage of stool and cleansing purulent wounds You can prepare a hypertonic solution at home. You cannot make your own sterile drug for intravenous administration, nor can you administer it this remedy at home without a doctor's prescription.

The pharmaceutical form of the drug is available in bottles of 200 and 400 ml; only distilled water is used for dilution and the dry substance is calculated per 1 liter. For topical use, regular boiled water, cooled to a temperature of 35–37 degrees (this temperature to accelerate dissolution) and regular salt from the kitchen.

How to prepare a hypertonic solution in terms of 200 ml of water (the volume of a faceted glass up to the rim):

Storing a homemade solution does not require special conditions - antimicrobial activity prevents the growth of bacteria. The shelf life is limited by salt crystallization (easy to determine by eye).

In conclusion, it can be noted that saline solution in the treatment of purulent-inflammatory processes in some cases successfully replaces expensive medications local application.

SOLUTIONS

Solutions are homogeneous mixtures of two or a large number of substances (components), which are evenly distributed in the form of individual atoms, ions, molecules.

There are true, colloidal solutions and suspensions.

True solutions They are characterized by transparency, have small sizes of dissolved particles, and easily pass through biological membranes. Depending on the salt concentration, there are three types of solutions: isotonic; hypertensive; hypotonic;

1. Isotonic solutions have the same concentration of salts as in the blood plasma, and the same osmotic pressure.

These include solutions with a salt concentration of 0.9%.

One of these solutions is saline - this is a solution sodium chloride -NaCl 0,9%. In such a solution, water molecules will move into and out of the cell in equal quantities in both directions.

C cl = C solution C – salt concentration

In this solution the cell retains everything vitally important functions, carrying out the processes of respiration, reproduction, metabolism.

Application of saline solution.

Inject saline solution through the mouth, intravenously, intramuscularly, subcutaneously, into the rectum:

in some diseases - severe prolonged diarrhea, cholera, uncontrollable vomiting, extensive burns, sodium chloride is released from the body in larger quantities than usual. Also, a lot of it is lost through sweat when working in hot shops. In such cases, its deficiency occurs in the body, which is accompanied by the development of a number of painful phenomena: spasms, convulsions, circulatory disorders, central nervous system depression;

in case of intoxication, blood loss, dehydration, high temperature

for washing the eyes and nasal cavity.

sodium chloride is an integral part of solutions used as blood-substituting (plasma-substituting) liquids.

2. HYPERTONIC SOLUTION (2%, 5%, 10%, 15%) - This is a solution in which the concentration of salts is higher than in blood plasma.

These include solutions containing more than 0.9% salts. If a cell is placed in such a solution, then water from the cell enters the environment, while the turgor (osmotic) pressure in the cell drops, the contents of the cell shrink, it loses its shape, and dehydration occurs. This phenomenon is called- plasmolysis

With class< С раствор

The phenomenon of plasmolysis is reversible; if you place a cell in a hypotonic solution, then in such a solution it will restore the volume and shape of the H 2 0 cell

A hypertonic solution is used for:

gargling, for baths, rubdowns;

Prescribed for constipation to empty the bowels.

in the form of compresses and lotions they are used in the treatment of purulent wounds, the wounds are cleansed of pus;

2 – 5% solutions are used for gastric lavage in case of silver nitrate poisoning;

used intravenously for pulmonary edema and internal bleeding.

3. Hypotonic solution , This is a solution that has a lower concentration of salts than in blood plasma. These include di-bidistilled water, melt water glaciers If a cell is placed in a hypotonic solution, then water will flow into it from the solution, the osmotic pressure increases, and the cell swells. This phenomenon is called - deplasmolysis.

C cl > C solution

Animal cells are quickly destroyed in such a solution because the membrane cannot withstand high osmotic pressure and ruptures. This phenomenon is called cytolysis . Special cases of cytolysis - destruction of red blood cells - hemolysis , in this case, hemoglobin enters the blood plasma and colors it red, such blood is called varnish .

Plant cells in such a solution usually only swell, because In addition to the cytoplasmic membrane, they have a dense cell wall - a cellulose membrane. But, if plant cells are kept in a hypotonic solution for a long time, then they too are destroyed.

Hypotonic solutions are used as solvents for water-soluble drugs. Through pinocytosis, nutrients from the bloodstream, hormones, enzymes, and drugs enter the cells.

a) elodea leaf cells b) plasmolysis in elodea leaf cells (in 10% sodium chloride solution)

Suspensions or suspensions- turbid liquids with particles larger than 0.2 microns. During settling, suspended particles settle.

Colloidal solutions. If the particles have intermediate sizes from 0.1 to 0.001 microns, that is, too large to form a true solution, but also too small to precipitate, a colloidal solution arises (Greek co11a-glue). Since the diameter of protein molecules exceeds 0.001 microns, proteins form colloidal solutions and all protoplasm is a colloid. In colloidal solutions, huge total areas are created on the surfaces of particles

Water molecules are firmly connected to protein molecules by hydrogen bonds. The smallest particles of substances surrounded by water molecules formcolloidal solutions are cytoplasm, karyoplasm, intercellular fluids. In a colloidal solution, a continuous phase is distinguished - dispersion medium (water) and colloidal particles - dispersed phase. Colloidal particles of protoplasm are most often protein molecules, because their sizes correspond to the sizes of colloidal particles.

Around the protein in a colloidal solution are formed aquatic or SOLVATE(from Latin solvare - to dissolve) shells. Solvate bound water firmly held by colloidal particles of proteins. Water molecules, creating shells around proteins, prevent the formation of large particles. This condition is called d i s p e r s ny m(scattered, fragmented).

Dispersity (degree of fragmentation) is inversely proportional to the size of colloidal particles

d = , Whered- dispersion, r is the size of the colloidal particle.

Colloidal particles are, as it were, suspended in a dispersion medium, where a huge surface is created on which sedimentation, adsorption of substances entering the cell and the course of various biochemical reactions occur.

Colloidal solutions come in two states : as Zola ( dissolved) Andgel ( jelly, more viscous ).

Gels dispersed systems . Ablegel elongated protein molecules touching, form with each other mesh frame filled with liquid.

Colloidal sols with particles that move freely. When protein molecules(colloidal particles) diverge, the colloid goes intosol .

These processes are reversible and occur continuously in the cell. At When a muscle contracts, the sol quickly turns into a gel and vice versa. At formation of pseudopodia in amoeba observed transition of gel to sol.

This transition from one state to another can be observed in a solution of gelatin, which when heated is liquid (sol), and when cooled it becomes gelatinous (gel).

The colloidal state determines viscosity.Viscosity increases and dispersion decreases, for example, when cells are damaged, the sizes of colloidal particles become larger due to swelling and aggregation.

PHYSICAL- CHEMICALPROPERTIESPROTOPLASMA

THE CONCEPT OF DISPERSE SYSTEMS, COLLOIDAL AND CRYSTALLINE STATES OF PROTOPLASMA

Protoplasm is characterized by a number of physicochemical properties. This is due to the fact that it is a complex combination of colloidal solutions of protein and other organic substances with true solutions of salts and a number of inorganic compounds. Protoplasm is a stable hydrophilic colloid. The colloidal state of protoplasm determines its viscosity. In most cells, the consistency of the cytoplasmic matrix exceeds the viscosity of water by no more than 5-10 times, but in some cases it can be significantly higher. The viscosity of protoplasm depends on metabolic processes in cells. Thus, it increases when the cell is damaged, and in eggs - after fertilization. During cell division, a rhythmic change in the viscosity of protoplasm is detected. Blood viscosity changes depending on the physiological and pathological state of the body.

Previously, the only physical state of protoplasm was considered colloidal. But in Lately It was discovered that a number of cellular structures are liquid crystals. Liquid crystals, unlike real crystals, which have a regular alternation of their constituent molecules in three dimensions, are ordered only in two dimensions. Liquid crystals occupy an intermediate position between liquids and crystals. On the one hand, like liquids, they have fluidity and can merge with each other; on the other hand, like crystals, they are characterized by anisotropy, that is, their strength, electrical conductivity and a number of other properties are not the same in different directions. The characteristics of liquid crystals are important for understanding a number of life processes: they sometimes exhibit the ability to move, and they often divide by budding. Apparently, the liquid crystalline state of a number of cellular structures ensures their greater lability (mobility, variability).

Lipids have a great ability to form liquid crystals. Liquid crystalline structure found in sperm, red blood cells, cells nervous system and nerve fibers, rods and cones of the retina.

Classification

There are three options for tonicity: one solution in relation to another can be isotonic, hypertonic and hypotonic.

Isotonic solutions

Hypotonic solutions

A hypotonic solution is a solution that has lower osmotic pressure relative to another, that is, it has a lower concentration of a substance that does not penetrate the membrane. When a cell is immersed in a hypotonic solution, osmotic penetration of water into the cell occurs with the development of its hyperhydration - swelling followed by cytolysis. Plant cells in this situation they are not always damaged; when immersed in a hypotonic solution, the cell will increase turgor pressure, resuming its normal functioning.

Effect on cells

In animal cells, a hypertonic environment causes water to leave the cell, causing cellular shrinkage (crenation). In plant cells, exposure hypertonic solutions more dramatic. The flexible cell membrane extends from the cell wall, but remains attached to it in the plasmodesmata region. Plasmolysis develops - the cells acquire a “needle-like” appearance, plasmodesmata practically cease to function due to contraction.

Some organisms have specific mechanisms to overcome hypertension environment. For example, fish living in hypertensive saline solution, maintain intracellular osmotic pressure, actively releasing excess salt drunk. This process is called osmoregulation.

In a hypotonic environment, animal cells swell to the point of rupture (cytolysis). To remove excess water, freshwater fish constantly urinate. Plant cells resist the effects of hypotonic solutions well due to a strong cell wall that provides effective osmolarity or osmolality.

Some drugs for intramuscular use are preferably administered in the form of a slightly hypotonic solution, which allows for better tissue absorption.

Notes

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