Question 1

Which of the following best describes the role of the Na+-K+ pump in maintaining the resting membrane potential of a neuron?

Accepted Answer

It actively transports Na+ out of the cell and K+ into the cell, maintaining their respective concentration gradients.

Question 2

A patient is exposed to a toxin that blocks all voltage-gated Na+ channels in neurons. What would be the most immediate effect on neuronal signaling?

Accepted Answer

Action potentials would not be generated, preventing long-distance neural communication.

Question 3

Which equation correctly represents Ohm’s law as applied to the neuronal membrane?

Accepted Answer

$$V = IR$$

Question 4

During the depolarization phase of an action potential, which of the following occurs?

Accepted Answer

Voltage-gated Na+ channels open, allowing Na+ to enter the cell.

Question 5

Which of the following best explains why graded potentials decay with distance from the stimulus site?

Accepted Answer

Current is lost through the leaky plasma membrane, causing the voltage to decline.

Question 6

A neuron is exposed to a drug that increases the permeability of the membrane to K+. What is the most likely effect on the resting membrane potential?

Accepted Answer

The membrane potential will become more negative (hyperpolarize).

Question 7

Which of the following is TRUE regarding the absolute refractory period during an action potential?

Accepted Answer

No stimulus, regardless of strength, can initiate another action potential.

Question 8

Saltatory conduction is faster than continuous conduction because:

Accepted Answer

Myelin sheaths prevent leakage of charge and action potentials jump from gap to gap.

Question 9

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

Accepted Answer

If threshold is reached, an action potential is generated; if not, none occurs.

Question 10

A patient has a genetic mutation that results in fewer myelin sheath gaps (nodes of Ranvier) along their axons. What is the most likely effect on nerve conduction?

Accepted Answer

Conduction velocity will decrease because fewer action potentials can be regenerated.

Question 11

Which type of gated channel opens in response to the binding of a neurotransmitter?

Accepted Answer

Chemically gated (ligand-gated) channel

Question 12

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

Accepted Answer

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

Question 13

Which of the following best explains why action potentials do not decay over distance, unlike graded potentials?

Accepted Answer

Action potentials are regenerated at each segment of the axon by voltage-gated channels.

Question 14

Which group of nerve fibers would transmit pain signals from a stubbed toe to the brain the slowest?

Accepted Answer

Group C fibers

Question 15

A neuron receives a stimulus that depolarizes the membrane from -70 mV to -60 mV. What is the most likely outcome?

Accepted Answer

A graded potential will occur, but an action potential may not be generated.

Question 16

Which of the following is a correct statement about the propagation of an action potential in a nonmyelinated axon?

Accepted Answer

The action potential is regenerated at each point along the axon, resulting in slow conduction.

Question 17

Which of the following best describes the effect of increasing axon diameter on conduction velocity?

Accepted Answer

Conduction velocity increases because larger diameter fibers have less resistance to local current flow.

Question 18

During which phase of the action potential are voltage-gated Na+ channels inactivated and voltage-gated K+ channels open?

Accepted Answer

Repolarization

Question 19

Which of the following is a property of graded potentials but NOT action potentials?

Accepted Answer

They decay with distance from the stimulus.

Membrane Potentials and Action Potentials in Neurons

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