For each of the following, indicate whether the condition will cause the membrane potential to become more positive, more negative, or largely unchanged when compared to the normal physiological resting membrane potential.

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Physics

Kennedy Barber

8 June, 02:42

For each of the following, indicate whether the condition will cause the membrane potential to become more positive, more negative, or largely unchanged when compared to the normal physiological resting membrane potential.

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Sage Dean · Answer 1

A. Hyperpolarize (more negative) because there is more K + inside at RMP, so to go down its gradient, it moves out. More leak channels, more positive charge leaves.

B. Depolarize (more positive) because there is more Na + outside at RMP, so Na + going down its gradient would be moving into the cell.

C. Hyperpolarize (less positive = more negative) because this statement means decreasing the Na + gradient, which means not as much Na + will enter the cell.

D. Depolarize (more positive). K + leak channels let K + out of the cell by simple diffusion, but now the K + channels are closed, so less K + leaves.

E. Depolarize (less negative = more positive). This reduces the K + gradient. Less K + is likely to leak out of the cell. Not to mention all of that charge repulsion!

F. No change. Changing the size of the cell does not affect RMP a lot. All this means is there is more K + inside the cell, but there is now more Na + outside the cell, so there is still a steady state potential across the cell membrane. What determines whether a cell depolarizes or hyperpolarizes is the presence of functional channels and whether they are closed or opened.