Osmosis

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Osmosis is very important in the biological systems, as water moves across cell membranes by osmosis. Water movement is essential to maintain the osmolarity of the cell.   
 
Osmosis is very important in the biological systems, as water moves across cell membranes by osmosis. 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:
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Osmolarity is defined as the number of water particles per unit volume, it can be calculated using the formula:  
  
 
Osm = M ([[Concentration|concentration]]) x n (number of particles)  
 
Osm = M ([[Concentration|concentration]]) x n (number of particles)  
  
Water will always move from an area of low osmolarity to an area of high osmolarity.  
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Water will always move from an area of low osmolarity to an area of high [[Osmolarity|osmolarity]].  
  
[[Cell|Cells]]&nbsp;can&nbsp;encounter potential problem when maintaining their intracellular osmolarity due to presence of&nbsp;[[Metabolites|metabolites]], e.g. sugars, [[amino-acids|amino-acids]] and nucleotides. Metabolites are large in size and highly charged. They&nbsp;do not contribute directly to the osmalarity but they&nbsp;can attract many counterions, e.g. Na<sup>+</sup>&nbsp;and K<sup>+</sup> ions,&nbsp;which significantly contribute to osmolarity. To counter this problem, cells actively pump out Na<sup>+</sup>, so their intracellular fluid contains less amount of&nbsp;organic [[Ion|ions]] than the extracellular fluid. This maintains&nbsp;osomotic equilibriu&nbsp;</span><ref>(Alberts B et al.,2008:664)</ref>.
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[[Cell|Cells]]&nbsp;can&nbsp;encounter potential problem when maintaining their intracellular osmolarity due to presence of&nbsp;[[Metabolites|metabolites]], e.g. sugars, [[Amino-acids|amino-acids]] and nucleotides. Metabolites are large in size and highly charged. They&nbsp;do not contribute directly to the osmalarity but they&nbsp;can attract many counterions, e.g. Na<sup>+</sup>&nbsp;and K<sup>+</sup> ions,&nbsp;which significantly contribute to osmolarity. To counter this problem, cells actively pump out Na<sup>+</sup>, so their intracellular fluid contains less amount of&nbsp;organic [[Ion|ions]] than the extracellular fluid. This maintains&nbsp;osomotic equilibriu&nbsp;&lt;/span&gt;<ref>(Alberts B et al.,2008:664)</ref>.  
  
 
=== An example of osmosis:  ===
 
=== An example of osmosis:  ===
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=== References''':'''  ===
 
=== References''':'''  ===
  
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Revision as of 03:59, 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 water moves across cell membranes by osmosis. 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 osmalarity 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 osomotic equilibriu </span>[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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