Q: During the depolarization phase of an action potential, which ion moves most rapidly across the neuronal membrane, and in which direction?

Na\textsuperscript{+} moves into the cell

Q: A dentist uses lidocaine as a local anesthetic. What is the primary mechanism by which lidocaine prevents pain sensation?

It blocks voltage-gated Na\textsuperscript{+} channels, preventing action potential propagation

Q: Which phase of the action potential is primarily responsible for the absolute refractory period?

Repolarization, due to inactivated Na\textsuperscript{+} channels

Q: During the repolarization phase of an action potential, which ion channel opens and what is the direction of ion movement?

K\textsuperscript{+} channels open, K\textsuperscript{+} moves out

Question 1

Which event directly triggers the opening of voltage-gated Na	extsuperscript{+} channels during the initiation of an action potential?

Accepted Answer

The membrane potential reaching threshold

Question 2

During the depolarization phase of an action potential, which ion moves most rapidly across the neuronal membrane, and in which direction?

Accepted Answer

Na	extsuperscript{+} moves into the cell

Question 3

Which of the following best describes the 'all-or-none' principle of action potentials?

Accepted Answer

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

Question 4

A dentist uses lidocaine as a local anesthetic. What is the primary mechanism by which lidocaine prevents pain sensation?

Accepted Answer

It blocks voltage-gated Na	extsuperscript{+} channels, preventing action potential propagation

Question 5

Which phase of the action potential is primarily responsible for the absolute refractory period?

Accepted Answer

Repolarization, due to inactivated Na	extsuperscript{+} channels

Question 6

If a neuron receives multiple subthreshold stimuli in rapid succession, what process allows these to combine and potentially trigger an action potential?

Accepted Answer

Temporal summation

Question 7

Which equation best represents the Nernst equation for calculating the equilibrium potential for K	extsuperscript{+}?

Accepted Answer

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

Question 8

Why do action potentials propagate unidirectionally along an axon?

Accepted Answer

Due to the refractory period, which prevents backward propagation

Question 9

Which of the following factors increases the speed of action potential conduction along an axon?

Accepted Answer

Increased myelination

Question 10

A patient has a genetic mutation that reduces the diameter of their peripheral nerve axons. What effect would this likely have on nerve conduction velocity?

Accepted Answer

It would decrease conduction velocity due to more resistance

Question 11

During the repolarization phase of an action potential, which ion channel opens and what is the direction of ion movement?

Accepted Answer

K	extsuperscript{+} channels open, K	extsuperscript{+} moves out

Question 12

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

Accepted Answer

Myelin allows action potentials to jump between nodes of Ranvier (saltatory conduction)

Question 13

A neuron is in the relative refractory period. What is required to generate another action potential at this time?

Accepted Answer

A stimulus much stronger than normal

Question 14

Which of the following best describes the role of the Na	extsuperscript{+}/K	extsuperscript{+} ATPase after an action potential?

Accepted Answer

It restores the resting membrane potential by pumping Na	extsuperscript{+} out and K	extsuperscript{+} in

Question 15

Which scenario would most likely result in a neuron failing to generate an action potential?

Accepted Answer

The membrane potential remains below threshold despite multiple stimuli

Question 16

Which of the following is a consequence of the absolute refractory period in neurons?

Accepted Answer

A second action potential cannot be generated regardless of stimulus strength

Question 17

If a neuron receives simultaneous inputs from multiple presynaptic neurons, what is this process called?

Accepted Answer

Spatial summation

Question 18

Which of the following best explains why pain and temperature sensations are conducted more slowly than touch and pressure sensations?

Accepted Answer

Pain and temperature fibers have smaller diameters and are less myelinated

Question 19

A patient is exposed to a toxin that selectively blocks voltage-gated K	extsuperscript{+} channels. What effect would this have on the action potential?

Accepted Answer

It would prolong repolarization and delay return to resting potential

Action Potentials and Electrical Signaling in Neurons

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