$$E = \frac{RT}{zF} \ln \left( \frac{[\text{ion}]_{\text{outside}}}{[\text{ion}]_{\text{inside}}} \right)$$

Question 1

Which of the following best describes the type of message sent by neurons during an action potential?

Accepted Answer

An electrical impulse generated by the movement of ions across the membrane

Question 2

Action potentials are most commonly found in which type of cell?

Accepted Answer

Muscle cells and neurons

Question 3

Which of the following correctly orders the phases of an action potential?

Accepted Answer

Depolarization → Repolarization → Hyperpolarization → Resting state

Question 4

During the depolarization phase of an action potential, which ion primarily moves into the neuron?

Accepted Answer

Sodium ($$Na^+)$$

Question 5

What is the typical resting membrane potential of a neuron?

Accepted Answer

$$-70 mV$$

Question 6

Which ion is most responsible for repolarizing the neuron after an action potential?

Accepted Answer

Potassium ($$K^+) $$leaving the cell

Question 7

A patient is given a drug that blocks voltage-gated sodium channels. What effect would this have on neuronal signaling?

Accepted Answer

Action potentials would be unable to initiate

Question 8

Which phase of the action potential is characterized by the membrane potential becoming more negative than the resting potential?

Accepted Answer

Hyperpolarization

Question 9

What is the main function of the sodium-potassium pump ($$Na^+/K^+$$ ATPase) in maintaining the resting membrane potential?

Accepted Answer

It actively transports $$3$$ $$Na^+$$ out and $$2$$ $$K^+$$ into the cell, maintaining the negative resting potential

Question 10

If extracellular potassium concentration increases significantly, what effect would this have on the resting membrane potential?

Accepted Answer

The resting membrane potential would become less negative (closer to zero)

Question 11

Which of the following best explains why action potentials only travel in one direction along an axon?

Accepted Answer

The refractory period prevents the action potential from moving backward

Question 12

During which phase of the action potential are voltage-gated sodium channels inactivated?

Accepted Answer

Repolarization

Question 13

A neuron is exposed to a toxin that keeps potassium channels open longer than normal. What is the most likely effect on the action potential?

Accepted Answer

The neuron will experience prolonged hyperpolarization

Question 14

Which of the following equations best represents the Nernst equation for calculating the equilibrium potential of an ion?

Accepted Answer

$$E = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{outside}}}{[	ext{ion}]_{	ext{inside}}} ight)$$

Question 15

Which of the following best describes the state of ion channels in a neuron at rest?

Accepted Answer

Voltage-gated sodium and potassium channels are closed

Question 16

A neuron receives multiple excitatory and inhibitory signals at the same time. What determines whether it will fire an action potential?

Accepted Answer

The sum of all signals must reach the threshold potential

Question 17

Which of the following is true about the movement of ions during the action potential?

Accepted Answer

$$Na^+$$ moves in, $$K^+$$ moves out

Question 18

Which of the following would most likely occur if the sodium-potassium pump stopped functioning in a neuron?

Accepted Answer

The resting membrane potential would dissipate and the neuron would be unable to fire action potentials

Question 19

Which phase of the action potential is associated with the rapid influx of $$Na^+$$ ions?

Accepted Answer

Depolarization

Question 20

A neuron is at rest. Which of the following best describes the distribution of $$Na^+$$ and $$K^+$$ ions?

Accepted Answer

$$Na^+ is $$higher outside, $$K^+ is $$higher inside

Neuronal Communication and Action Potentials

Study Guide - Practice Questions