Question 1

A patient is experiencing muscle weakness due to a genetic defect that reduces the number of voltage-gated sodium channels in their neurons. Which phase of the action potential is most directly affected by this defect?

Accepted Answer

Depolarization

Question 2

Which equation correctly represents Ohm's law as applied to neuronal membranes?

Accepted Answer

$$V = I 	imes R$$

Question 3

A neuron is exposed to a toxin that increases membrane permeability to potassium ions. What is the most likely effect on the resting membrane potential?

Accepted Answer

The membrane potential will become more negative (hyperpolarize)

Question 4

Which type of ion channel opens in response to physical deformation of the receptor, such as touch or pressure?

Accepted Answer

Mechanically-gated channel

Question 5

During the absolute refractory period, why can't a neuron generate another action potential?

Accepted Answer

Voltage-gated sodium channels are open or inactivated

Question 6

Which of the following best describes saltatory conduction in myelinated axons?

Accepted Answer

Action potentials jump from one node of Ranvier to the next

Question 7

A neuron receives multiple subthreshold stimuli at its dendrites, but does not fire an action potential. Which zone of a neuronal pool is this neuron most likely located in?

Accepted Answer

Facilitated zone

Question 8

Which of the following neuron types is most abundant in the human body and is primarily found in the central nervous system?

Accepted Answer

Multipolar neuron

Question 9

A patient has a mutation that impairs the function of the Na+/K+ pump in neurons. What is the most likely consequence?

Accepted Answer

Ionic gradients across the membrane will dissipate

Question 10

Which of the following best explains why action potentials only travel in one direction along an axon?

Accepted Answer

Voltage-gated sodium channels behind the action potential are inactivated (refractory period)

Question 11

A researcher stimulates a neuron with a weak stimulus that does not reach threshold. What type of potential is most likely generated?

Accepted Answer

Graded potential

Question 12

Which of the following is true regarding the relationship between current, voltage, and resistance in neurons?

Accepted Answer

Current decreases as resistance increases, if voltage is constant

Question 13

Which type of neural circuit is most likely involved in rhythmic activities such as breathing?

Accepted Answer

Reverberating circuit

Question 14

A patient with multiple sclerosis has damage to myelin sheaths in their CNS. Which conduction type is most affected?

Accepted Answer

Saltatory conduction

Question 15

Which group of nerve fibers transmits impulses at the fastest rate?

Accepted Answer

Group A fibers

Question 16

A neuron is exposed to a neurotransmitter that opens chemically-gated sodium channels. What is the most likely immediate effect?

Accepted Answer

Depolarization of the membrane

Question 17

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

Accepted Answer

Action potentials are generated only if threshold is reached, and always have the same amplitude

Question 18

Which neuron type is primarily responsible for transmitting sensory information from the skin to the CNS?

Accepted Answer

Unipolar (pseudounipolar) neuron

Question 19

A patient is exposed to a drug that blocks all leakage (nongated) potassium channels in neurons. What is the most likely effect on the resting membrane potential?

Accepted Answer

The resting membrane potential will become less negative

Question 20

Which of the following best explains why higher frequency of action potentials indicates a stronger stimulus?

Accepted Answer

More action potentials are generated per unit time

Nervous System – Part 2: Neuron Structure, Electrical Principles, and Signal Transmission

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