Question 1

Which of the following best describes the role of the Na+/K+ ATPase 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, creating concentration gradients for both ions.

Question 2

A neuron is exposed to a toxin that blocks voltage-gated Na+ channels. What is the most likely effect on neuronal signaling?

Accepted Answer

The neuron will be unable to generate action potentials.

Question 3

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

Accepted Answer

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

Question 4

Which equation best represents the Nernst equation for calculating the equilibrium potential for K+?

Accepted Answer

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

Question 5

A patient is given a drug that increases the permeability of the neuronal membrane to K+ at rest. What is the most likely effect on the resting membrane potential?

Accepted Answer

The resting membrane potential will become more negative (hyperpolarized).

Question 6

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

Accepted Answer

Voltage-gated Na+ channels become refractory and cannot reopen immediately after closing.

Question 7

Which of the following is a direct result of neurotransmitter binding to ligand-gated ion channels on the postsynaptic membrane?

Accepted Answer

A graded postsynaptic potential is produced, which may be excitatory or inhibitory.

Question 8

If a neuron receives simultaneous excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs), what determines whether an action potential will be generated?

Accepted Answer

The sum of all EPSPs and IPSPs at the axon hillock relative to the threshold potential.

Question 9

Which of the following best describes the effect of myelination on action potential propagation?

Accepted Answer

It allows action potentials to jump between nodes of Ranvier, increasing conduction speed.

Question 10

A researcher uses tetrodotoxin (TTX) to block voltage-gated Na+ channels in a neuron. Which experimental result would best support the conclusion that TTX blocks action potentials?

Accepted Answer

The resting membrane potential remains unchanged, but no action potentials are observed after stimulation.

Question 11

Which of the following is true about the 'all-or-none' nature of action potentials?

Accepted Answer

If threshold is reached, an action potential of fixed magnitude and duration is generated.

Question 12

Which of the following best explains why the peak of the action potential is close to the equilibrium potential for Na+?

Accepted Answer

During depolarization, the membrane becomes highly permeable to Na+, allowing Na+ to flow in until the membrane potential approaches $$E_{Na}.$$

Question 13

Which of the following scenarios would most likely result in an inhibitory postsynaptic potential (IPSP)?

Accepted Answer

Opening of ligand-gated K+ channels, allowing K+ to exit the cell.

Question 14

Which of the following is a key difference between graded potentials and action potentials?

Accepted Answer

Graded potentials decrease in magnitude with distance, while action potentials do not.

Question 15

A neuron is exposed to a drug that prevents the reuptake of neurotransmitters from the synaptic cleft. What is the most likely effect?

Accepted Answer

Postsynaptic potentials will be prolonged due to continued neurotransmitter binding.

Question 16

Which of the following best describes the process of summation in neuronal signaling?

Accepted Answer

The additive effect of multiple EPSPs and IPSPs on the postsynaptic membrane potential.

Question 17

Which of the following is a direct effect of the influx of Ca2+ into the presynaptic terminal during synaptic transmission?

Accepted Answer

Fusion of synaptic vesicles with the presynaptic membrane and release of neurotransmitter.

Question 18

Which of the following would most likely increase the speed of action potential propagation along an axon?

Accepted Answer

Increasing the degree of myelination.

Question 19

Which of the following best explains why the resting membrane potential is typically negative?

Accepted Answer

The membrane is more permeable to K+ ions, which leak out, leaving behind negatively charged ions.

Neuronal Signaling: Structure, Function, and Mechanisms

Guida di studio - Domande di pratica

Study guide - Flashcard