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7 Cards in this Set
- Front
- Back
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write the nernst equation
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Ex = -60mV/z log[Xi]/[Xo]
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what does the nernst equation tell you?
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electrical force (which cancels out the diffusional force)
means ion x is at equil. A given ion can only be at equilibrium when the voltage across the membrane is at Ex(Vm = Ex) |
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ion concentration change and nernst equation
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only a very small number of ions relative to the bulk pool will actually cross to create the membrane potential, thus [ion] will not change significantly
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driving force on an ion
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the driving force is proportional to the membranes potential and the ion equilibrium potential Vm - Ek
tells you the voltage inside the cell(outside is 0mV) |
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what does the GHK equation give you?
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the actual value of Vm, given relative permeabilities of ions x,y,z, . . etc
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nernst
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increasing the permeability of an ion will tend to drive Vm toward the Nernst potential Ex of that ion
the more permeable you are, the more Vm will look like your specific Ex |
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GHK equation
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-60log [K]i + alpha[Na]i / [K]o + [alpha[Na]o
alpha - Pna/Pk |
