Equilibrium/membrane potential question- anatomy

proZach

proZach

Active member
i already know this is probably not going to help me out too much, but why not.
i have a test on friday on human anatomy and physiology and have this problem. i'm pretty sure that when the membrane potential of a cell and equilibrium potential of an ion are different, and if the cell is permeable to that ion, and if that ion channel happens to be open, there is an ionic flow. however, i don't know which way it would be. now i know it is dependent on those numbers (Vm and Eion).
to put numbers to this, when Vm is, for example, -82mV and ENa+ is 69, what happens? Would the Na+ flow out of the cell to try to balance it out to reach equilibrium? and would this be a depolarization or a hyperpolarization? or am i wrong haha
 
Na+ would flow across the cell membrane from the side charged at +68mV to the side at -85mV. Trying to reach an equilibrium. If the area inside the cell has the negative charge and is consequently moving to a smaller negative charge it would be depolarization. If the area inside the cell has the positive charge and it would be repolarization or hyperpolarization.
 
ENa+ means the equilibrium potential derived from the nernst equation. which is something like rT/zF x log [IONout/IONin].
but you pretty much have it. and cliffsomething you got it. i asked my professor today and he just cleared it up. if the Vm is -70, and K+ is -110, K rushes out of the cell. if Na+ is +70, it goes into the cell. if i'm wrong, than fuckit i'm going to fail anyways.
 
that was probably like 2% of the entire test. now i just have a zillion more to go. so i'm on ns instead. summer classes was a poor choice
 
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