Q: A neuron has a higher concentration of K extsuperscript{+} inside the cell and a higher concentration of Na extsuperscript{+} outside the cell. Which equation best describes the equilibrium potential for K extsuperscript{+}?

$$E_{K} = \frac{RT}{zF} \ln \left( \frac{[K^+]_{\text{out}}}{[K^+]_{\text{in}}} \right)$$

Question 1

Which of the following best describes the role of the Na	extsuperscript{+}/K	extsuperscript{+}-ATPase in maintaining the resting membrane potential?

Accepted Answer

It actively transports 3 Na	extsuperscript{+} ions out of the cell and 2 K	extsuperscript{+} ions into the cell, helping to maintain concentration gradients.

Question 2

What is the approximate value of the resting membrane potential in a typical neuron?

Accepted Answer

$$-70\ \mathrm{mV}$$

Question 3

Which factor is MOST important in generating the resting membrane potential?

Accepted Answer

The difference in plasma membrane permeability to Na	extsuperscript{+} and K	extsuperscript{+}.

Question 4

If the Na	extsuperscript{+}/K	extsuperscript{+}-ATPase is inhibited, what would be the most likely effect on the resting membrane potential?

Accepted Answer

The membrane potential would gradually become less negative as ion gradients dissipate.

Question 5

Which of the following statements about leak channels is correct?

Accepted Answer

Leak channels are responsible for the passive movement of ions, contributing to the resting membrane potential.

Question 6

A neuron has a higher concentration of K	extsuperscript{+} inside the cell and a higher concentration of Na	extsuperscript{+} outside the cell. Which equation best describes the equilibrium potential for K	extsuperscript{+}?

Accepted Answer

$$E_{K} = \frac{RT}{zF} \ln \left( \frac{[K^+]_{	ext{out}}}{[K^+]_{	ext{in}}} ight)$$

Question 7

Which of the following would most likely occur if the permeability of the plasma membrane to Na	extsuperscript{+} suddenly increased?

Accepted Answer

The resting membrane potential would become less negative (depolarize).

Question 8

Which of the following is a direct consequence of the Na	extsuperscript{+}/K	extsuperscript{+}-ATPase activity?

Accepted Answer

Maintenance of a higher concentration of Na	extsuperscript{+} outside and K	extsuperscript{+} inside the cell.

Question 9

A mutation causes the Na	extsuperscript{+}/K	extsuperscript{+}-ATPase to transport only 2 Na	extsuperscript{+} out for every 2 K	extsuperscript{+} in. What effect would this have on the resting membrane potential?

Accepted Answer

The resting membrane potential would become less negative.

Question 10

Which of the following best explains why the inside of a neuron is more negative than the outside at rest?

Accepted Answer

The Na	extsuperscript{+}/K	extsuperscript{+}-ATPase pumps more positive charges out than in, and K	extsuperscript{+} leak channels allow K	extsuperscript{+} to exit the cell.

Question 11

Which of the following would most likely decrease the magnitude of the resting membrane potential?

Accepted Answer

Decreasing the activity of the Na	extsuperscript{+}/K	extsuperscript{+}-ATPase.

Question 12

Which of the following is NOT a factor contributing to the resting membrane potential?

Accepted Answer

Equal distribution of ions across the membrane.

Question 13

A patient is given a drug that increases the permeability of the neuronal membrane to K	extsuperscript{+}. What is the most likely effect?

Accepted Answer

The neuron will hyperpolarize.

Question 14

Which of the following best describes the effect of increasing extracellular K	extsuperscript{+} concentration on the resting membrane potential?

Accepted Answer

The resting membrane potential becomes less negative.

Question 15

Which formula can be used to calculate the resting membrane potential considering multiple ions?

Accepted Answer

$$E_{m} = \frac{RT}{F} \ln \left( \frac{P_{K}[K^+]_{	ext{out}} + P_{Na}[Na^+]_{	ext{out}} + P_{Cl}[Cl^-]_{	ext{in}}}{P_{K}[K^+]_{	ext{in}} + P_{Na}[Na^+]_{	ext{in}} + P_{Cl}[Cl^-]_{	ext{out}}} ight)$$

Question 16

Which of the following is the main reason why the Na	extsuperscript{+}/K	extsuperscript{+}-ATPase is considered electrogenic?

Accepted Answer

It moves more positive charges out of the cell than into the cell.

Question 17

A neuron is exposed to a toxin that blocks all Na	extsuperscript{+} leak channels. What is the most likely effect on the resting membrane potential?

Accepted Answer

The resting membrane potential would become more negative.

Question 18

Which of the following best explains why the Na	extsuperscript{+}/K	extsuperscript{+}-ATPase requires ATP?

Accepted Answer

It moves ions against their concentration gradients.

Membrane Potential and Resting Membrane Potential in Neurons

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