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Biol 216 5 The Neuron 61-90.pdf

Biol 216 5 The Neuron 61-90.pdf - Membrane potential...

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5/18/17 1 Membrane potential Resting membrane potential: equilibrium condition, no net flow of ions across the plasma membrane (refers to a cell that is not transmitting an electrical impulse) Equilibrium potential: the membrane potential at which the voltage gradient of the ion balances the concentration gradient for the ion(refers to specific ion); no net flow of ion through channel (refers to an ion) Electrochemical gradient: drives the flow of any ion through a membrane channel protein, consists of voltage gradient and concentration gradient of the ion across the membrane Shown is the distribution of ions that produces a resting potential ( about-70mV) K+ leak channel
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5/18/17 2 Resting Membrane Potential Animations: http://www2.yvcc.edu/Biology/109Modules/Modules/RMP/R MP.htm http://www.st-andrews.ac.uk/~wjh/neurotut/mempot.html Nerst Equation When all the constants are entered in, we get the classic Nernst equation for predicting the equilibrium potential (in mV) across the membrane of a cell for a singly charged positive ion ( E ion ) : E ion = 62mV log 10 [X] outside [X] inside E K+ = -90mV So…when the inside of the membrane is 90mV more negative than the outside, K+ is at equilibrium Note: Equilibrium potential: the membrane potential at which the voltage gradient of a particular ion balances the concentration gradient for the ion; no net flow of ion through channel
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5/18/17 3 Resting Potential If E K+ = -90mV…why is resting potential of a neuron -70mV?
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