Question 1

Which of the following best describes the resting membrane potential of a typical neuron?

Accepted Answer

It is approximately $$-70 mV$$, with the inside of the cell more negative than the outside.

Question 2

Which ion is most responsible for maintaining the resting membrane potential due to its high permeability through leak channels?

Accepted Answer

Potassium ($$K^+)$$

Question 3

A neuron receives a stimulus that opens gated $$Na^+$$ channels, causing the membrane potential to move from $$-70 mV to$$ $$-55 mV. $$What term best describes this change?

Accepted Answer

Depolarization

Question 4

Which of the following statements about graded potentials is TRUE?

Accepted Answer

Graded potentials are short-lived and decrease in intensity with distance.

Question 5

During the generation of an action potential, what is the primary event occurring during the repolarization phase?

Accepted Answer

$$K^+$$ channels open and $$K^+$$ rushes out of the cell.

Question 6

Which of the following best explains why action potentials are described as 'all-or-none' events?

Accepted Answer

Action potentials only occur if the membrane potential reaches threshold; otherwise, they do not occur at all.

Question 7

A patient has a genetic mutation that reduces the number of voltage-gated $$Na^+$$ channels in their neurons. Which phase of the action potential would be most affected?

Accepted Answer

Depolarization

Question 8

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

Accepted Answer

Increasing the degree of myelination

Question 9

Saltatory conduction is characterized by:

Accepted Answer

Action potentials jumping from one node of Ranvier to the next in myelinated axons.

Question 10

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

Accepted Answer

No action potential can be generated, regardless of stimulus strength.

Question 11

If a neuron is exposed to a toxin that blocks $$K^+$$ channels, what would most likely happen during an action potential?

Accepted Answer

Repolarization would be delayed or prevented.

Question 12

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

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 13

A neuron receives multiple weak stimuli in rapid succession, resulting in a higher frequency of action potentials. What property of neural signaling does this illustrate?

Accepted Answer

Frequency coding

Question 14

Which of the following best distinguishes graded potentials from action potentials?

Accepted Answer

Graded potentials decrease in strength with distance, while action potentials do not.

Question 15

Which of the following scenarios would most likely result in hyperpolarization of a neuron?

Accepted Answer

Opening of $$K^+$$ channels

Question 16

A neuron is exposed to a drug that increases the permeability of its membrane to $$Na^+. $$What effect would this have on the resting membrane potential?

Accepted Answer

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

Question 17

Which of the following is a direct result of the Na$$^+-K$^+$$ pump activity in neurons?

Accepted Answer

Maintenance of higher $$K^+$$ concentration inside and higher $$Na^+$$ concentration outside the cell.

Question 18

Which of the following best describes the role of the axon hillock in neural signaling?

Accepted Answer

It is the site where action potentials are typically initiated.

Question 19

A patient with multiple sclerosis has damaged myelin sheaths in their neurons. Which of the following would most likely be observed?

Accepted Answer

Slower action potential conduction due to impaired saltatory conduction.

Fundamentals of the Nervous System & Nervous Tissue 11C: Membrane Potentials and Action Potentials

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