osmosis /os·mo·sis/ (oz-mo´sis) (os-mo´sis) the diffusion of pure solvent across a membrane in response to a concentration gradient, usually from a solution of lesser to one of greater solute concentration.osmot´ic
osmosis (osm)
osmosis [oz-mo´sis, os-mo´sis]
os·mo·sis ( z-m  s s, s-)n. pl. os·mo·ses (-s  z) 1. Diffusion of fluid through a semipermeable membrane until there is an equal concentration of fluid on both sides of the membrane. 2. The tendency of fluids to diffuse in such a manner. os·mot ic (-mtk) adj. |
osmosis (osm)
[ozmō′sis, os-]
Etymology: Gk, ōsmos, impulse, osis, condition
the movement of a pure solvent such as water through a differentially permeable membrane from a solution that has a lower solute concentration to one that has a higher solute concentration. The membrane is impermeable to the solute but is permeable to the solvent. The rate of osmosis depends on the concentration of solute, the temperature of the solution, the electrical charge of the solute, and the difference between the osmotic pressures exerted by the solutions. Movement across the membrane continues until the concentrations of the solutions equalize. osmotic (osm), adj.
osmosis [oz-mo´sis, os-mo´sis]
the diffusion of pure solvent across a membrane in response to a concentration gradient, usually from a solution of lesser to one of greater solute concentration. adj., adj osmot´ic.
The process of osmosis and the factors that influence it are important clinically in the maintenance of adequate body fluids and in the proper balance between volumes of extracellular and intracellular fluids.
The term osmotic pressure refers to the amount of pressure necessary to stop the flow of water across the membrane. The hydrostatic pressure of the water exerts an opposite effect; that is, it exerts pressure in favor of the flow of water across the membrane. The osmotic pressure of the particles in a solute depends on the relative concentrations of the solutions on either side of the membrane, and on the area of the membrane. The osmotic pressure exerted by the nondiffusible particles in a solution is determined by the numbers of particles in a unit of fluid and not by the mass of the particles.
The process of osmosis and the factors that influence it are important clinically in the maintenance of adequate body fluids and in the proper balance between volumes of extracellular and intracellular fluids.
The term osmotic pressure refers to the amount of pressure necessary to stop the flow of water across the membrane. The hydrostatic pressure of the water exerts an opposite effect; that is, it exerts pressure in favor of the flow of water across the membrane. The osmotic pressure of the particles in a solute depends on the relative concentrations of the solutions on either side of the membrane, and on the area of the membrane. The osmotic pressure exerted by the nondiffusible particles in a solution is determined by the numbers of particles in a unit of fluid and not by the mass of the particles.
If the solution surrounding a cell has the same solute concentration as the internal environment of the cell (isotonic), the flow rates in and out of the cell are the same, and the cell remains the same size. If the solute concentration outside the cell is lower (hypotonic), more water will flow into the cell than out, and the cell will swell and perhaps burst. If the solute concentration outside the cell is greater (hypertonic), more water will flow out of the cell than into it, and the cell will shrivel.
Demonstration of osmotic pressure on the two sides of a semipermeable membrane.
osmosis (ozmō´sis),
n the passage of pure solvent from the lesser to the greater concentration when two solutions are separated by a membrane that selectively prevents the passage of solute molecules but is permeable to the solvent. The principles of osmosis and the selective permeability of the cell membrane help to regulate the transfer of fluids and metabolites to and from the cells. Thus, they also maintain the stability of the salt/ion concentration in the extracellular and intracellular fluids.
osmosis
[Gr.] the passage of pure solvent from a solution of lesser to one of greater solute concentration when the two solutions are separated by a membrane which selectively prevents the passage of solute molecules, but is permeable to the solvent.
The process of osmosis and the factors that influence it are important clinically in the maintenance of adequate body fluids and in the proper balance between volumes of extracellular and intracellular fluids.
The term osmotic pressure refers to the amount of pressure necessary to stop the flow of water across the membrane. The hydrostatic pressure of the water exerts an opposite effect; that is, it exerts pressure in favor of the flow of water across the membrane. The osmotic pressure of the particles in a solute depends on the relative concentrations of the solutions on either side of the membrane, and on the area of the membrane. The osmotic pressure exerted by the nondiffusible particles in a solution is determined by the numbers of particles in a unit of fluid and not by the mass of the particles.
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Osmosis. By permission from Guyton R, Hall JE, Textbook of Medical Physiology, Saunders, 2000
osmosis
A passive process of movement of water through a semipermeable membrane in response to a concentration gradient, from an area of low solute (e.g. glucose molecules) concentration (i.e. high water concentration) to one of high solute concentration (i.e. low water concentration). The membrane is permeable to water but relatively impermeable to solutes. See osmotic pressure; hypertonic solution.
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