Osmosis

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Osmosis is the movement of [[Water|water]] molecules from a high water concentration (hypotonic solution) to a low water [[Concentration|concentration]] (hypertonic solution) through a [[Semi-permeable membrane|semi-permeable membrane.]] It can also be described as the movement of water from a low [[Solute|solute]] concentration to a high solute concentration through a [[Semi-permeable membrane|semi-permeable membrane]].  
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Osmosis is the movement of [[Water|water]] molecules from a high water concentration ([[Hypotonic solution|hypotonic solution]]) to a low water [[Concentration|concentration]] ([[Hypertonic solution|hypertonic solution]]) through a [[Semi-permeable membrane|semi-permeable membrane.]] It can also be described as the movement of water from a low [[Solute|solute]] concentration to a high solute concentration through a [[Semi-permeable membrane|semi-permeable membrane]].  
  
*Concentration gradients affects osmosis, the higher the concentration gradient the higher the osmosis rate.  
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*Concentration gradients affect osmosis, the higher the concentration gradient the higher the [[Osmosis rate|osmosis rate]].  
*Osmosis can be decreased by increasing the osmotic pressure of the hypertonic solution relative to the hypotonic solution <ref>Patlak, J., (2000) Osmosis, available at http://physioweb.uvm.edu/bodyfluids/osmosis.htm (last accessed 14/11/2011).</ref>.
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*Osmosis can be decreased by increasing the osmotic pressure of the hypertonic solution relative to the hypotonic solution<ref>Patlak, J., (2000) Osmosis, available at http://physioweb.uvm.edu/bodyfluids/osmosis.htm (last accessed 14/11/2011).</ref>.
  
Osmosis is very important in the biological systems, as water moves across cell membrane by osmosis. Water movement is essential to maintain the osmolarity of the cell.&nbsp;
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Osmosis is very important in the biological systems, as it is required to allow the movement of water across a cell, and water movement is essential to maintain the osmolarity of the cell.  
  
Osmolarity is defined as the number of water particles per unit volume, it can be calculated using the formula:<br>Osm = M ([[Concentration|concentration]]) x n (number of particles)
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Osmolarity is defined as the number of water particles per unit volume, it can be calculated using the formula:  
  
Water will always move from an area of low osmolarity to an area of high osmolarity.
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Osm = M ([[Concentration|concentration]]) x n (number of particles)
  
An example of osmosis:<br>Plants absorb water through their roots by osmosis
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Water will always move from an area of low osmolarity to an area of high [[Osmolarity|osmolarity]].
  
Cells have&nbsp;a potential problem when maintaining their intracellular osmolarity due to&nbsp;metabolites e.g. sugars, amino-acids and nucleotides. These are large in size and highly charged, which attract many counterions. Thus significantly contribute to osmolarity. To control this problem cells actively pump out Na+, so their intracellular fluid contains a decreased number of inorganic ions than the extracellular fluid. This maintains&nbsp;osomotic equilibrium .<ref>(Alberts B et al.,2008:664)</ref>  
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[[Cell|Cells]] can encounter potential problem when maintaining their intracellular osmolarity due to presence of [[Metabolites|metabolites]], e.g. sugars, [[Amino-acids|amino-acids]] and nucleotides. Metabolites are large in size and highly charged. They do not contribute directly to the osmolarity but they can attract many counterions, e.g. Na<sup>+</sup> and K<sup>+</sup> ions, which significantly contribute to osmolarity. To counter this problem, cells actively pump out Na<sup>+</sup>, so their intracellular fluid contains less amount of organic [[Ion|ions]] than the extracellular fluid. This maintains osmotic equilibriu<ref>(Alberts B et al.,2008:664)</ref>.
  
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=== An example of osmosis ===
  
<br>
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Plants absorb water through their roots by osmosis.
  
<br>. <br>
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=== References ===
 
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'''References:'''
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Latest revision as of 11:40, 5 December 2017

Osmosis is the movement of water molecules from a high water concentration (hypotonic solution) to a low water concentration (hypertonic solution) through a semi-permeable membrane. It can also be described as the movement of water from a low solute concentration to a high solute concentration through a semi-permeable membrane.

Osmosis is very important in the biological systems, as it is required to allow the movement of water across a cell, and water movement is essential to maintain the osmolarity of the cell.

Osmolarity is defined as the number of water particles per unit volume, it can be calculated using the formula:

Osm = M (concentration) x n (number of particles)

Water will always move from an area of low osmolarity to an area of high osmolarity.

Cells can encounter potential problem when maintaining their intracellular osmolarity due to presence of metabolites, e.g. sugars, amino-acids and nucleotides. Metabolites are large in size and highly charged. They do not contribute directly to the osmolarity but they can attract many counterions, e.g. Na+ and K+ ions, which significantly contribute to osmolarity. To counter this problem, cells actively pump out Na+, so their intracellular fluid contains less amount of organic ions than the extracellular fluid. This maintains osmotic equilibriu[2].

An example of osmosis

Plants absorb water through their roots by osmosis.

References

  1. Patlak, J., (2000) Osmosis, available at http://physioweb.uvm.edu/bodyfluids/osmosis.htm (last accessed 14/11/2011).
  2. (Alberts B et al.,2008:664)
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