Question 1

Which of the following best describes the property of action potentials in neurons?

Accepted Answer

They are constant in magnitude and duration, regardless of stimulus intensity.

Question 2

A researcher applies a steady voltage $$V_0 at $$one point along an axon. According to the cable model, what is the voltage $$V(x) at a $$distance $$x$$ from the point of application, given the length constant $$\lambda$$?

Accepted Answer

$$V(x) = V_0$ e$$^{-x/\lambda}$$

Question 3

Which of the following is NOT a function of sensory neurons?

Accepted Answer

Controlling muscle contraction

Question 4

During an action potential, what is the typical peak value of the membrane potential inside the axon?

Accepted Answer

$$+30\ \mathrm{mV}$$

Question 5

What is the primary role of interneurons in the nervous system?

Accepted Answer

They transmit information between neurons.

Question 6

A nerve impulse is generated only if the stimulus exceeds a certain threshold. What is the physiological significance of this threshold?

Accepted Answer

It ensures that only strong enough stimuli can trigger an action potential, preventing random firing.

Question 7

Which of the following best describes the direction of signal propagation in a typical neuron?

Accepted Answer

From dendrites to cell body to axon

Question 8

In the vertebrate nervous system, how is the action potential typically transmitted across the synapse to another neuron or muscle cell?

Accepted Answer

By the release of a chemical neurotransmitter that diffuses across the synaptic gap

Question 9

If the length constant $$\lambda of an $$axon is $$0.8\ \mathrm{mm}$$, what percentage of the original voltage remains at a distance of $$0.8\ \mathrm{mm}$$ from the point of application?

Accepted Answer

About 37%

Question 10

Which of the following is a correct statement about the duration of action potentials in muscle fibers compared to neurons?

Accepted Answer

Action potentials in muscle fibers are usually longer in duration than those in neurons.

Question 11

A patient is exposed to a stimulus that does not reach the threshold for action potential generation. What is the expected response in the neuron?

Accepted Answer

No action potential is generated.

Question 12

Which of the following best explains why the action potential is described as 'all-or-none'?

Accepted Answer

Once the threshold is reached, the action potential always has the same magnitude and duration.

Question 13

During an action potential, after the membrane potential peaks, it rapidly decreases to a value near:

Accepted Answer

$$-90\ \mathrm{mV}$$

Question 14

Which of the following is a real-world application of understanding axon cable properties in medicine?

Accepted Answer

Diagnosing demyelinating diseases such as multiple sclerosis, which affect signal propagation.

Question 15

A fast-acting axon can propagate an action potential at speeds up to:

Accepted Answer

$$100\ \mathrm{m/s}$$

Question 16

Which of the following experimental methods is commonly used to study the electrical properties of axons?

Accepted Answer

Inserting a probe into the axon and measuring voltage changes with respect to the surrounding fluid.

Question 17

Which of the following is NOT a typical stimulus that can elicit a nerve impulse in an experimental setting?

Accepted Answer

Exposure to ultraviolet light

Question 18

If a voltage $$V_0 is $$applied to an axon and the voltage at $$x = 0.8\ \mathrm{mm} is $$measured to be $$0.37 V_0$, what is the length constant $$\lambda$$ of the axon?

Accepted Answer

$$0.8\ \mathrm{mm}$$

Question 19

Which of the following best describes the function of dendrites in a neuron?

Accepted Answer

They receive input signals from other neurons.

Biophysics: Electrobiology of the Nervous System, Action Potentials, and Axon Circuits

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