the_na-k_pump - the Na moves into the cell right That is...

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The Na-K Pump Some of you expressed interest in the sodium/potassium pump above and beyond its usefulness as an example of active transport. So, you asked for it: The sodium/potassium pump is found in all animal cells and serves a very important role in the “firing” of neurons. Here is a brief explanation: Neurons, like many cells in our body, have an overall negative electrical charge relative to the extracellular environment. This difference in charge is called the “resting potential” and makes the neuron very responsive to changes in their environment (like those messages we were talking about). So, the neuron wants to maintain this negative charge or the resting potential. How does it do this? Glad you asked. Look at the following numbers: Neuron Blood [K + ] 0.400M 0.020M [Na + ] 0.050M 0.440M If I were to ask you which direction these ions would move via diffusion, you would say that the K moves out of the cell and
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Unformatted text preview: the Na moves into the cell, right? That is not what happens! What actually happens is that the sodium/potassium pump moves K into the cell and Na out and moves these ions in a ratio of 3 Na out : 2 K in (look at the above figure), thus maintaining the proper concentrations in the cell. Remember that the neuron has an overall negative charge relative to its environment. How? Because the cell is shipping out all of those sodium cations in a 3 Na:2 K ratio. This is why the 3:2 ratio is important – it helps to maintain the proper concentration of ions. The proper concentrations for what? To maintain the resting potential of the neuron, thus making the neuron ready to receive and send messages to other neurons. So I hope that serves to answer in more detail some of the really good questions that have been asked!...
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This note was uploaded on 04/02/2008 for the course BIOL 123 taught by Professor Shaner during the Spring '08 term at New Mexico.

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the_na-k_pump - the Na moves into the cell right That is...

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