What is a hypertonic environment? Hypo-, hyper- and isotonic solutions. Isotonic coefficient. How do solutions differ?
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 are not always damaged in this situation; 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, the effects of hypertonic solutions are 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 environmental hypertonicity. For example, fish living in a hypertonic saline solution maintain intracellular osmotic pressure by actively excreting excess salt they drink. 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.
see also
Notes
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See what “Tonicity” is in other dictionaries:
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∆A is the thermodynamically reversible work expended on the formation of a surface of area ∆S. Since work is done on the system, it is negative.
Force definition surface tension is a force acting on a surface tangentially to it and tending to reduce the free surface of the body to the smallest possible limits for a given volume.
"liquid - liquid" depends on the nature of the contacting phases: the greater the difference in the polarity of the phases, the greater the surface tension at their interface.
Surface tension at the boundary "liquid - gas" measure of a heterogeneous system. As pressure increases, the interaction of surface molecules of the liquid with molecules of the gas phase increases and the excess energy of molecules on the surface decreases, as well as surface tension decreases.
Osmolarity
Osmolarity is the sum of the concentrations of cations, anions and non-electrolytes, i.e. of all kinetically active particles in 1 liter. solution. It is expressed in milliosmoles per liter (mOsm/L).
Osmolarity values are normal
Blood plasma – 280-300
CSF – 270-290
Urine – 600-1200
Osmolarity index – 2.0-3.5
Free water clearance – (-1.2) – (-3.0) ml/min
Determining osmolarity helps:
1. Diagnose hyper- and hypo-osmolar syndromes
2. Identify and purposefully treat hyperosmolar comatose states and hypoosmolar overhydration.
3. Diagnose acute renal failure in the early period.
4. Assess the effectiveness of transfusion and infusion therapy.
5. Diagnose acute intracranial hypertension.
Hypoosmolarity, hyperosmolarity
Determining osmolarity is a very complex laboratory diagnostic test. However, its implementation makes it possible to timely identify symptoms of disorders such as hypoosmolarity, that is, a decrease in blood plasma osmolarity, and hyperosmolarity, on the contrary, an increase in osmolarity. The reason for the decrease in osmolarity can be various factors, for example, an excess of the level of free water contained in the blood plasma relative to the volume of kinetic particles dissolved in it. Actually, we can talk about hypoosmolarity when the level of osmolarity of blood plasma drops below 280 mOsm/l. Symptoms that may indicate a disorder such as hypoosmolarity include fatigue, headache, nausea leading to vomiting and decreased appetite. As the disorder develops, the patient experiences pathological reflexes, oliguria, bulbar palsy and depression of consciousness.
As for such a disorder as hyperosmolarity, it is caused, as already mentioned, by an increase in the osmolarity of the blood plasma. At the same time, the critical level is above 350 mOsm, l. Timely detection of hyperosmolarity is of particular importance, since this disorder is the most common cause of coma in diabetes mellitus. It is hyperosmolarity that can not only be the cause of coma for patients with diabetes, but also cause its occurrence due to lactic acidosis or ketoacidosis. Thus, monitoring the level of osmolarity of blood plasma is really of great importance, since it allows you to monitor the stable state of the body and prevent various types of disorders in a timely manner.
Isotonic solutions - aqueous solutions isotonic to blood plasma. The simplest solution of this type is a 0.9% aqueous solution of sodium chloride (NaCl) - the so-called physiological solution (“saline”). This name is very conditional, since “saline solution” does not contain many substances (in particular, potassium salts) necessary for the physiological activity of body tissues.
Isotonic coefficient(Also van't Hoff factor; denoted by i) is a dimensionless parameter characterizing the behavior of a substance in solution. It is numerically equal to the ratio of the value of a certain colligative property of a solution of a given substance and the value of the same colligative property of the non-electrolyte concentration, with other parameters of the system unchanged:
Where solut.- this solution, nel. solut.- non-electrolyte solution of the same concentration, T bp- boiling point, and T mp- melting point (freezing point).
The role of osmosis and osmotic pressure in biological systems. The phenomenon of osmosis plays an important role in many chemical and biological systems. Thanks to osmosis, the flow of water into cells and intercellular structures is regulated. The elasticity of cells (turgor), which ensures the elasticity of tissues and the preservation of a certain shape of organs, is due to osmotic pressure. Animal and plant cells have membranes or a surface layer of protoplasm that have the properties of semi-permeable membranes. When these cells are placed in solutions with different concentrations, rsmosis is observed
Osmosis plays an important role in many biological processes. The membrane surrounding a normal blood cell is permeable only to molecules of water, oxygen, some of the nutrients dissolved in the blood and cellular waste products; for large protein molecules that are in a dissolved state inside the cell, it is impenetrable. Therefore, proteins so important for biological processes remain inside the cell.
Osmosis is involved in the transfer of nutrients in the trunks of tall trees, where capillary transport is unable to perform this function.
Since ancient times, humanity, although not understanding the physical meaning, has used the effect of osmosis in the process of salting food. As a result, plasmolysis of the pathogen cells occurred.
Plasmolysis (from ancient Greek πλάσμα - fashioned, shaped and λύσις - decomposition, decay), separation of the protoplast from the cell wall in a hypertonic solution.
Plasmolysis is preceded by a loss of turgor.
Plasmolysis is possible in cells that have a dense cell wall (plants, fungi, large bacteria). Animal cells that do not have a hard shell contract when they enter a hypertonic environment, but no separation of the cellular contents from the shell occurs. The nature of plasmolysis depends on a number of factors:
on the viscosity of the cytoplasm;
from the difference between the osmotic pressure of the intracellular and external environment;
on the chemical composition and toxicity of the external hypertonic solution;
on the nature and number of plasmodesmata;
on the size, number and shape of vacuoles.
A distinction is made between corner plasmolysis, in which the separation of the protoplast from the cell walls occurs in separate areas. Concave plasmolysis, when the detachment covers large areas of the plasmalemma, and convex, complete plasmolysis, in which the connections between neighboring cells are almost completely destroyed. Concave plasmolysis is often reversible; In a hypotonic solution, cells regain lost water and deplasmolysis occurs. Convex plasmolysis is usually irreversible and leads to cell death.
There are also convulsive plasmolysis, similar to convex plasmolysis, but differing from it in that the cytoplasmic filaments connecting the compressed cytoplasm to the cell wall are preserved, and cap plasmolysis, characteristic of elongated cells.
Cytolysis - the process of destruction of eukaryotic cells, expressed in the form of their complete or partial dissolution under the action of lysosomal enzymes. Cytolysis can be either part of normal physiological processes, for example during embryogenesis, or a pathological condition that occurs when the cell is damaged by external factors, for example, when the cell is exposed to antibodies.
10.Ionic product of water. Hydrogen index. Determination of the pH of aqueous solutions of acids, bases and salts (this is in the text, but ask Dima) Give examples of pH values of various biological media. (Dima)
Ionic product of water.
Water is a very weak electrolyte. Its electrolytic dissociation is expressed by the equilibrium:
pH value
For convenience of the nature of the aquatic environment, a dimensionless value is used - the pH value.
Hydrogen index is a quantitative characteristic of the acidity of the medium, equal to the negative logarithm of the concentration of free hydrogen ions in the solution: pH= -lg
pH = 7 – neutral environment
pH< 7 – кислая среда
pH > 7 – alkaline environment
Just in case, hydrolysis.
Hydrolysis of salts. Hydrolysis by cation and anion, calculation of pH of salts. Factors that enhance hydrolysis.
Hydrolysis of salts is a reversible exchange reaction of a substance with water to form a weak electrolyte.
There are 3 options for hydrolysis of salts:
By anion
By cation
By anion and cation.
Factors that enhance hydrolysis
Which are lower than in the cells of plant or animal tissues. In G. r. cells absorb water, increasing in volume, and lose some of the osmotically active substances (organic and mineral). Red blood cells of animals and humans in G. r. swell to such an extent that their shells burst and they are destroyed. This phenomenon is called Hemolysis. Wed. Hypertonic solutions and Isotonic solutions.
Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .
See what “Hypotonic solutions” are in other dictionaries:
- (biological), solutions whose osmotic pressure is lower than the osmotic pressure in the cells of the body. * * * HYPOTONIC SOLUTIONS HYPOTONIC SOLUTIONS, in biology, solutions whose osmotic pressure is lower than the osmotic pressure in ... ... encyclopedic Dictionary
- (biol.), pry, osmotic. pressure below osmotic. pressure in the cells of the body... Natural science. encyclopedic Dictionary
In biology, solutions whose osmotic pressure is lower than the osmotic pressure in the cells of the body ... Big Encyclopedic Dictionary
hypertonic and hypotonic solutions- Hypertonic and hypotonic solutions: if two solutions have different osmotic pressures, then the solution with a higher osmotic pressure is called hypertonic with respect to the second solution, and the solution with a lower osmotic pressure... ... Chemical terms
Solutions whose osmotic pressure is higher than the osmotic pressure in plant or animal cells and tissues. Depending on the functional, species and environmental specifics of the cells, the osmotic pressure in them is different, and the solution... ...
- (from Iso... and Greek tónos voltage) solutions with the same osmotic pressure (See Osmotic pressure); in biology and medicine, natural or artificially prepared solutions with the same osmotic pressure as in the contents... ... Great Soviet Encyclopedia
SODIUM- SODIUM. Natrium, chemical element, symbol Na, a silvery-white, shiny, monatomic metal with a waxy density at ordinary temperatures, becoming brittle in the cold and distilling in bright red-hot heat; discovered by De.wi (1807) by electrolysis... ...
Interaction of red blood cells with solutions depending on ... Wikipedia
ENEMA- ENEMA, clyster (Greek: klyzo, I rinse), a technical technique consisting in introducing any liquid substance into the rectum - water, medicinal solutions, oil, liquid suspensions, etc. The main purpose of K is a therapeutic effect;... ... Great Medical Encyclopedia
- (from the Greek plásma fashioned, shaped and lýsis decomposition, decay) lag of the Protoplast from the shell when the cell is immersed in a hypertonic solution (See Hypertonic solutions). P. is characteristic mainly of plant cells... Great Soviet Encyclopedia
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