Q: Which of the following best describes the process of depolarization during an action potential?

The membrane potential becomes more positive due to Na\textsuperscript{+} influx.

Question 1

Which of the following best describes the process of depolarization during an action potential?

Accepted Answer

The membrane potential becomes more positive due to Na	extsuperscript{+} influx.

Question 2

What is the role of the 'ball and chain' mechanism in voltage-gated Na	extsuperscript{+} channels during an action potential?

Accepted Answer

It blocks the channel during repolarization, causing inactivation.

Question 3

At which location on a neuron is the action potential typically initiated?

Accepted Answer

Axon hillock

Question 4

Which statement correctly describes the 'all-or-none' principle of action potentials?

Accepted Answer

Once threshold is reached, an action potential of fixed size is always generated.

Question 5

During the absolute refractory period, which of the following is true?

Accepted Answer

No action potential can be generated regardless of stimulus strength.

Question 6

Which factor would most likely increase the conduction velocity of an action potential along an axon?

Accepted Answer

Increasing the amount of myelination

Question 7

A patient has a genetic mutation that prevents proper inactivation of voltage-gated Na	extsuperscript{+} channels. What is the most likely effect on their action potentials?

Accepted Answer

Action potentials will fail to repolarize properly.

Question 8

Which equation best represents the change in membrane potential during depolarization?

Accepted Answer

$$ V_{m} = V_{rest} + \Delta V_{Na^+} $$

Question 9

Saltatory conduction is a process that:

Accepted Answer

Allows the action potential to 'jump' between nodes of Ranvier, increasing speed.

Question 10

If the resting membrane potential of a neuron is $$ -70 \ \mathrm{mV} $$ and the threshold potential is $$ -55 \ \mathrm{mV} $$, what must happen for an action potential to be triggered?

Accepted Answer

The membrane potential must reach at least $$ -55 \ \mathrm{mV} .$$

Question 11

During repolarization, which ion movement is primarily responsible for returning the membrane potential to its resting value?

Accepted Answer

Efflux of K	extsuperscript{+}

Question 12

Which of the following best explains why myelinated axons conduct action potentials faster than unmyelinated axons?

Accepted Answer

Myelin reduces ion leakage and allows the action potential to jump between nodes.

Question 13

A neuron is exposed to a toxin that blocks voltage-gated K	extsuperscript{+} channels. What is the most likely effect on the action potential?

Accepted Answer

Repolarization will be delayed or incomplete.

Question 14

Which of the following is true regarding the relative refractory period?

Accepted Answer

A second action potential can be generated if the stimulus is supra-threshold.

Question 15

Which of the following best describes hyperpolarization?

Accepted Answer

The membrane potential becomes more negative than resting potential.

Question 16

If a neuron has a larger diameter, what effect does this have on conduction velocity?

Accepted Answer

Conduction velocity increases due to decreased resistance.

Question 17

Which of the following scenarios would most likely result in a failure to generate an action potential?

Accepted Answer

The membrane potential remains at $$ -70 \ \mathrm{mV} .$$

Question 18

Which of the following best explains why action potentials do not decrease in amplitude as they travel down a myelinated axon?

Accepted Answer

Myelin prevents charge loss, enabling saltatory conduction.

Question 19

A neuron is stimulated at its axon hillock but fails to reach threshold. What is the most likely outcome?

Accepted Answer

No action potential is generated.

Action Potentials: Mechanisms, Phases, and Conduction in Neurons

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