Part of a neuron [Na+] = 150 mM [K+] = 5 mM -70 mV [Na+] = 15 mM [K+] = 150 mM N

Question

Part of a neuron [Na+] = 150 mM [K+] = 5 mM -70 mV [Na+] = 15 mM [K+] = 150 mM Na+ Channels K+ Channels The figure shows part of a neuron with the following labeled: Sodium ion (Na+) and potassium ion (K+) concentrations (measured in mM) Resting membrane potential (-70 mV) . Na+ and K+ channels The resting membrane of a neuron has many more open K+ channels than open Na+ channels. a) What would happen to the resting membrane potential if the concentration of K+ outside of the cell was increased from 5 mM to 50 mM? Required It will be more positive than -70 mV. It will be more negative than -70 mV It will stay the same at -70 mV. It will be about 0 mV. Explain your reasoning about what would happen to the resting membrane potential if the K+ concentration increased from 5 to 50 mM.

Explanation / Answer

It will be more positive than -70 mV
If the concentration of k+ outside the cell increases from 5mM to 50 mM. This will Cause a Depolarization (more positive) as Predicted by the GHK equation and there will be a Decrease in the gradient for K to leak out of the cell. So, the Less K leaks out of the cell (more positive charge inside the cell)

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