LS04 - NPB 12 Lecture 4 Membrane Potential: This is the...

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Unformatted text preview: NPB 12 Lecture 4 Membrane Potential: This is the potential (voltage) across the membrane that you measure. It will fluctuate depending on what is happening to the neuron. - 9 + 6 m e m b r a n e p o t e n t i a l ( m V ) t i m e Terms to Remember Resting Membrane Potential: This is the potential (voltage) across the membrane that you measure when nothing is happening to the neuron. Terms to Remember Equilibrium Potential (V eq ): This is the potential (voltage) across the membrane where a particular ion is in dynamic equilibrium . Each ion will move across the membrane (if it can) in the direction necessary to get the membrane to that potential. Terms to Remember **If the membrane potential is at the same value as the equilibrium potential for that ion, then there is no net movement of that ion across the membrane even if all the pores, etc. are open. **If pores or channels in the membrane for a specific ion are opened, that ion will move across the membrane in such a way to make the membrane potential equal to the equilibrium potential for that ion. Equilibrium Potential (V eq ): This is the potential (voltage) across the membrane where a particular ion is in dynamic equilibrium . Each ion will move across the membrane (if it can) in the direction necessary to get the membrane to that potential. K+ K+ C E Eventually, the two forces balance out, the K+ is in dynamic equilibrium , and this voltage is the equilibrium potential V = 1/+1 * T * K * log(small/big) V = +1 * some number * log(<1) V = some negative number Terms to Remember (1) K+ channel open: Resting Membrane Potential Eventually the chemical force driving K + out of the cell is equal to the electrical force driving K + into the cell. This is the equilibrium potential for K + , and would be the resting membrane potential except (1) K+ channel open: Resting Membrane Potential The chemical and electrical forces for Na+ drive the Na+ across the membrane into the cell. There are leak channels that allow some Na+ to cross the membrane, making the membrane potential more positive than the equilibrium potential for K+ (1) K+ channel open: (2) Leak channel open: Resting Membrane Potential...
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LS04 - NPB 12 Lecture 4 Membrane Potential: This is the...

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