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

Voltage-gated Na\textsuperscript{+} channels are inactivated in the region behind the action potential, preventing backward propagation.

Q: During the absolute refractory period, why is it impossible for another action potential to be generated?

Na\textsuperscript{+} channels are inactivated and cannot be reopened until the membrane repolarizes.

Q: Which of the following best describes the role of the inactivation gate in the voltage-gated Na\textsuperscript{+} channel?

It closes after a brief delay, stopping Na\textsuperscript{+} entry and contributing to the refractory period.

Q: Which equation best represents the Nernst potential for K\textsuperscript{+} across a neuronal membrane?

$$E_K = \frac{RT}{zF} \ln \left( \frac{[K^+]_{\text{outside}}}{[K^+]_{\text{inside}}} \right)$$

Question 1

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

Accepted Answer

Voltage-gated Na	extsuperscript{+} channels are inactivated in the region behind the action potential, preventing backward propagation.

Question 2

During the absolute refractory period, why is it impossible for another action potential to be generated?

Accepted Answer

Na	extsuperscript{+} channels are inactivated and cannot be reopened until the membrane repolarizes.

Question 3

What effect does opening voltage-gated K	extsuperscript{+} channels have on the excitability of a neuron?

Accepted Answer

It makes the neuron less likely to reach threshold, decreasing excitability.

Question 4

A neuron is exposed to a neurotransmitter that opens K	extsuperscript{+} channels. What is the most likely result?

Accepted Answer

The neuron becomes hyperpolarized and less likely to fire an action potential.

Question 5

Which of the following best describes the role of the inactivation gate in the voltage-gated Na	extsuperscript{+} channel?

Accepted Answer

It closes after a brief delay, stopping Na	extsuperscript{+} entry and contributing to the refractory period.

Question 6

Which equation best represents the Nernst potential for K	extsuperscript{+} across a neuronal membrane?

Accepted Answer

$$E_K = \frac{RT}{zF} \ln \left( \frac{[K^+]_{	ext{outside}}}{[K^+]_{	ext{inside}}} ight)$$

Question 7

Hyperkalemia (elevated plasma K	extsuperscript{+}) has which effect on the resting membrane potential of neurons?

Accepted Answer

It shifts the membrane potential closer to threshold, making the neuron more likely to depolarize.

Question 8

Which of the following is TRUE regarding the conduction of action potentials in myelinated versus unmyelinated axons?

Accepted Answer

Conduction is faster in myelinated axons due to saltatory conduction.

Question 9

Which of the following statements about neurotransmitter release at a chemical synapse is correct?

Accepted Answer

Neurotransmitter release requires both an action potential and Ca	extsuperscript{2+} entry into the presynaptic cell.

Question 10

Which process allows neurons to integrate multiple signals arriving at the same time from different synapses?

Accepted Answer

Spatial summation

Question 11

A patient is given a drug that blocks voltage-gated Ca	extsuperscript{2+} channels in presynaptic neurons. What is the most likely effect?

Accepted Answer

Neurotransmitter release into the synaptic cleft will be inhibited.

Question 12

Which of the following best describes the function of the blood-brain barrier?

Accepted Answer

It protects the brain from toxic water-soluble compounds and pathogens.

Question 13

Which structure produces cerebrospinal fluid (CSF) in the brain?

Accepted Answer

Choroid plexus

Question 14

Which of the following statements about spinal cord anatomy is correct?

Accepted Answer

Ventral roots carry efferent signals from the CNS to muscles and glands.

Question 15

Which of the following is a function of the cerebellum?

Accepted Answer

Coordination of movement and balance

Question 16

Which area of the cerebral cortex is responsible for processing somatic sensory information such as touch, pain, and temperature?

Accepted Answer

Primary somatosensory cortex

Question 17

Which hormone is released from the posterior pituitary and is involved in both childbirth and milk release?

Accepted Answer

Oxytocin

Question 18

Which of the following best describes long-term potentiation (LTP) in neural synapses?

Accepted Answer

A sustained change in the quality or quantity of synaptic connections, believed to underlie learning.

Question 19

Which equation best describes the relationship between membrane potential and ion concentrations according to the Goldman-Hodgkin-Katz equation?

Accepted Answer

$$V_m = \frac{RT}{F} \ln \left( \frac{P_{K^+}[K^+]_{	ext{out}} + P_{Na^+}[Na^+]_{	ext{out}} + P_{Cl^-}[Cl^-]_{	ext{in}}}{P_{K^+}[K^+]_{	ext{in}} + P_{Na^+}[Na^+]_{	ext{in}} + P_{Cl^-}[Cl^-]_{	ext{out}}} ight)$$

Neurons: Cellular and Network Properties – Action Potentials and Signal Conduction

Study Guide - Practice Questions

Study Guide - Flashcards