Resting membrane potential [K+] changed


Q.

The figure on the left shows part of a normal 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 normal neuron has many more open K+ channels than open Na+ channels.

 

What happens to the resting membrane potential if the concentration of K+ outside of the cell is changed from 5 mM to 50 mM? This changed neuron is shown in the figure on the right. Note: The concentrations of Na+ are not changed.

a. It will become more positive than -70 mV.

b. It will become more negative than -70 mV.

c. It will stay the same at -70 mV.

 

Explain your reasoning about what happens to the resting membrane potential if the concentration of K+ outside of the cell is changed from 5 mM to 50 mM and the concentrations of Na+ are not changed.

Audiences:

Undergraduate

Topics:

Ion movement

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