Difference between revisions of "Osmosis and Filtration - Anatomy & Physiology"
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+ | |backcolour = C1F0F6 | ||
+ | |linkpage =Transport Across Membranes - Physiology | ||
+ | |linktext =TRANSPORT ACROSS MEMBRANES | ||
+ | |maplink = Urinary System (Content Map) - Anatomy & Physiology | ||
+ | |pagetype =Anatomy | ||
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==Introduction== | ==Introduction== | ||
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Osmosis is the passive movement of water across a semi permeable membrane. It occurs in the opposite direction to diffusion of ions. Water moves from a region of low solute concentration and therefore high water concentration to a region of high solute concentration and low water concentration. | Osmosis is the passive movement of water across a semi permeable membrane. It occurs in the opposite direction to diffusion of ions. Water moves from a region of low solute concentration and therefore high water concentration to a region of high solute concentration and low water concentration. | ||
− | ==Pressure and | + | ==Pressure and Osmosis== |
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− | + | If you have two bodies of water, one pure and one with a solute dissolved in it, seperated by a membrane permeable to water but not the solute then water molecules from the pure water move to the side with the solute. This movement of water causes a fluid pressure differance at the entrance and exits of the holes in the membrane. At the side with the solute the fluid pressure is lower than at the side without however this pressure differance is only at the exit of the hole and not in the solution as a whole. This pressure differance is the actual cause of the movement of water. | |
− | + | ==Filtration== | |
− | + | However if you increase the pressure at one side of the membrane of the fluid as a whole you force more water through the membrane. If enough pressure is applied to the side with the solute then it can overcome the pressure differances across the pores and reverse them causing water to flow against its concentration gradient. | |
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Revision as of 16:35, 20 August 2008
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Introduction
Osmosis is the passive movement of water across a semi permeable membrane. It occurs in the opposite direction to diffusion of ions. Water moves from a region of low solute concentration and therefore high water concentration to a region of high solute concentration and low water concentration.
Pressure and Osmosis
If you have two bodies of water, one pure and one with a solute dissolved in it, seperated by a membrane permeable to water but not the solute then water molecules from the pure water move to the side with the solute. This movement of water causes a fluid pressure differance at the entrance and exits of the holes in the membrane. At the side with the solute the fluid pressure is lower than at the side without however this pressure differance is only at the exit of the hole and not in the solution as a whole. This pressure differance is the actual cause of the movement of water.
Filtration
However if you increase the pressure at one side of the membrane of the fluid as a whole you force more water through the membrane. If enough pressure is applied to the side with the solute then it can overcome the pressure differances across the pores and reverse them causing water to flow against its concentration gradient.