Why is the cell prefer K+ over Na+

  • Thread starter TuviaDaCat
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im asking this because chemically they are very similar, and the only big difference i see is that potassium is much larger.

i got the details for mammalian cell typical ion concentrations and it is such:
inside outside (mM)
K+ 5-15 145
Na+ 140 5

so what does the cell has against Na?
 

Answers and Replies

  • #2
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im asking this because chemically they are very similar, and the only big difference i see is that potassium is much larger.

i got the details for mammalian cell typical ion concentrations and it is such:
inside outside (mM)
K+ 5-15 145
Na+ 140 5

so what does the cell has against Na?
The gradient that is created is very important for many vital functions of our bodies to operate properly.
 
  • #3
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if we wanted a nice gradient then taking Na out would do, but it takes in K+
 
  • #4
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if we wanted a nice gradient then taking Na out would do, but it takes in K+
Positive feedback mechanism as well as a way to efficiently return to normal potential in the cell.
 
  • #5
Andy Resnick
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Cells use *both*- it depends on what you want to move in or out of the cell. Glucose intake, for example, is coupled to sodium transport (sodium-glucose cotransporter).
 
  • #6
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i think that the reason is that Na has a greater effect on osmosis, so by taking Na out and K in, the cell can maintain membrane structure
 
  • #7
somasimple
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A more real answer is here:
http://www1.lsbu.ac.uk/water/cell.html
The different characteristics of the intracellular and extracellular environments manifest themselves particularly in terms of restricted diffusion and a high concentration of chaotropic inorganic ions and kosmotropic other solutes within the cells. Note that both chaotropic inorganic ions and kosmotropic other solutes encourage low density water structuring. The difference in concentration of the ions is particularly apparent between Na+ and K+ (see below); Na+ ions creating more broken hydrogen bonding and preferring a high aqueous density whereas K+ ions prefer a low density aqueous environment. A 1000-fold preference for K+ over Na+ has been found in a halophilic organism without any energy expenditure but with a highly reduced intracellular water mobility [817]. As explained in discussion of the Hofmeister effect and shown by the negative apparent ionic volumes (that is, addition of the ions reduces the volume of the water, see below), the interactions between water and Na+ are stronger than those between water molecules, which in turn are stronger than those between water and K+ ions; all being explained by the differences in surface charge density. The interaction strength is reflected in that the distance between the Na+ ions and water is shorter than between two water molecules which is shorter than between K+ ions and water. Ca2+ ions have even stronger destructive effects, on the hydrogen bonding, than Na+ ions. Clearly, K+ ions are preferred within the intracellular environment.
K+ is a weak ion but more mobile than Na+.
This is also in this bible
https://www.amazon.com/dp/071677108X/?tag=pfamazon01-20
pages 43 - 70
I must Thanks Andy because he said it was a good book. (It is!)
 
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  • #8
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thanks for the recommendation for the book, but i already chose albert's.

its quite a thing molecular biology...
 

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