Question 1

Which of the following best describes the role of Schwann cells in the peripheral nervous system?

Accepted Answer

They form myelin sheaths around axons in the PNS, increasing the speed of action potential propagation.

Question 2

A patient presents with muscle weakness and slowed nerve conduction velocity. Demyelination is suspected. Which cell type is most likely affected in the peripheral nervous system?

Accepted Answer

Schwann cells

Question 3

Which equation is used to calculate the equilibrium potential for a specific ion across a membrane?

Accepted Answer

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

Question 4

During the resting membrane potential, which ion has the greatest permeability across the neuronal membrane?

Accepted Answer

Potassium ($K^+$)

Question 5

If the membrane potential of a neuron is at $-70$ mV and the equilibrium potential for potassium ($K^+$) is $-94$ mV, what is the net direction of $K^+$ movement?

Accepted Answer

$K^+$ will move out of the cell.

Question 6

Which of the following best explains why action potentials are 'all-or-nothing' events?

Accepted Answer

Once the membrane potential reaches threshold, voltage-gated $Na^+$ channels open, causing a rapid depolarization regardless of stimulus strength.

Question 7

A neuron receives a stimulus that depolarizes its membrane to $-60$ mV. The threshold for action potential generation is $-55$ mV. What will happen?

Accepted Answer

A graded potential will occur, but no action potential will be generated.

Question 8

Which structural type of neuron is most commonly found in the central nervous system and is characterized by multiple dendrites and a single axon?

Accepted Answer

Multipolar neuron

Question 9

Which of the following best describes the function of afferent neurons?

Accepted Answer

They transmit sensory information from the periphery to the CNS.

Question 10

Multiple sclerosis is a disease that affects the propagation of action potentials. Which process is most directly impaired?

Accepted Answer

Saltatory conduction along myelinated axons

Question 11

Which phase of the action potential is primarily due to the opening of voltage-gated $K^+$ channels?

Accepted Answer

Repolarization

Question 12

What is the main function of the axon hillock in a neuron?

Accepted Answer

It is the site where action potentials are generated if threshold is reached.

Question 13

Which of the following best describes the effect of increasing stimulus strength above threshold on action potentials?

Accepted Answer

It increases the frequency of action potentials generated.

Question 14

Which of the following is TRUE regarding graded potentials?

Accepted Answer

They decrease in magnitude as they spread away from the site of stimulation.

Question 15

Which of the following is a correct sequence of events during an action potential?

Accepted Answer

Resting potential → Depolarization → Repolarization → Hyperpolarization → Resting potential

Question 16

A neuron is exposed to a drug that blocks voltage-gated $Na^+$ channels. What is the most likely effect?

Accepted Answer

Action potentials will not be generated.

Question 17

Which of the following best explains the role of the sodium-potassium pump ($Na^+/K^+$ ATPase) in maintaining the resting membrane potential?

Accepted Answer

It actively transports $3$ $Na^+$ out and $2$ $K^+$ in, maintaining concentration gradients.

Question 18

Which part of the nervous system is responsible for 'rest and digest' functions?

Accepted Answer

Parasympathetic division of the autonomic nervous system

Question 19

A pseudo-unipolar neuron is most likely to be found in which functional class?

Accepted Answer

Afferent (sensory) neuron

Question 20

Which of the following would most likely result from a mutation that increases the number of $Na^+$ leak channels in a neuron?

Accepted Answer

The resting membrane potential would become less negative (closer to $+60$ mV).

Nerve Cells and Electrical Signaling: Structure and Function in Human Physiology

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