Electrical Activity of Cells
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What is the value for Ek and for Ena?
Ek is -90mv and Ena is +60mv
If a cell potential is close to -90mv, what does this stop? If a cell potential is close to +60mv, what does this mean?
Stops K+ leaving Stops Na+ entering
Why is the electrical potential of a cell much closer to Ek than Ena?
The cell membrane is about 50 times more permeable to K+ than Na+. There are more K+ channels open at rest.
Why at -90mv does the potassium not leave the cell?
So that the cell does not lose positive charge
What is the equation for the driving force on an ion?
Membrane resting potential - the equilibrium potential
Why is less force needed to push potassium out then needed to get sodium in?
There are more potassium channels in the membrane.
What does the Nernst equation assume that the Goldman Hodgkin Katz equation takes into account?
That the permeability of the membrane from sodium and potassium is equal.
How do you use the Nerst equation?
58 X log (shown below) The log = add the permeabilities of potassium and sodium out the cell divided by the permeabilities of in the cell added