What is the osmotic pressure
osmosis called unilateral spontaneous diffusion of solvent molecules through a semipermeable membrane from the less concentrated to a more concentrated solution.Semipermeable membrane is one which is permeable to the cell impermeable to solvent and dissolved therein particles.By definition, the osmotic pressure - it is the hydrostatic pressure applied to the solution, which can stop the diffusion of particles, ie osmosis.
Osmosis is widely distributed in nature.It is characteristic of all biological organisms.Osmotic pressure occurs when solutions separated by a semipermeable membrane.For example, take located in the cells and the extracellular fluid space.Normally, extracellular and intracellular osmotic pressure are the same.But if interstitial fluid loses water pressure therein increases.Under the action of high pressure water from the osmotic cell begins to diffuse into the extracellular space.Diffusion will stop only when the pressure level off.
What determines the osmotic pressure
pressure in the osmosis depends on how much dissolved particles contained in unit volume.These can be molecules, ions or other colloidal particles.One can say that the osmotic pressure due to the concentration of all particles, osmotically active, per unit volume.From the chemical properties of the solvent and dissolved substances therein, it is not dependent.
Scientists have found that the osmotic pressure obeys the same laws as the gas pressure.It can be measured with instruments called osmometers.They are a special kind of pressure gauges.These instruments are used semipermeable membrane of animal and synthetic origin.Pressure measurements show a direct dependence upon the concentration of the solution.
Act osmotic pressure, open Van Hoff, argues that its value numerically equal to this pressure, which would have the substance of the solution, being at the same temperature for an ideal gas, with the condition that its scope would be equal to the volumesolution.
Act described by the equation: p = i CRT
i- isotonic coefficient value;
C - concentration of the solution, expressed in moles;
R - value of the universal gas constant;
T - thermodynamic temperature.
value of the osmotic pressure of living organisms
Osmosis inherent in living nature, as all of the cells of plants and animals have a membrane permeable to water and impermeable to other substances.In living tissue, on the border cells and the intercellular fluid constantly acting osmotic pressure.It provides the lifting of nutrients and water from the ground to the leaves of plants and turgor of plant cells activity.
solution having the same osmotic pressure, called isotonic.Those in which the pressure is higher, called hypertonic, lower - hypotonic.
osmotic pressure of human blood is in the magnitude of 7.7 atm.People are able to feel the slightest hesitation it.For example, the thirst after taking salty foods linked to its increase.Local edema inflammations also occur due to an increase in osmotic pressure at the site of inflammation.
Knowledge of the laws of osmotic pressure in medicine is necessary for carrying out medical activities.Thus, physicians known that for intravenous administration can be used only plasma isotonic 0.9% NaCl solution.It does not cause tissue irritation.On the contrary, hypertensive 3-5% NaCl is used to better cleanse septic wounds from microorganisms and pus.
Knowledge of the laws of osmosis is necessary not only in medicine and biology.Without it can not do many types of human activity, including industry and energy.
