Question 1

Which of the following best describes the role of the sodium-potassium pump in establishing the resting membrane potential of a neuron?

Accepted Answer

It pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell using ATP.

Question 2

Given the following ion concentrations for a mammalian neuron: $$[K^+]_{inside} = 140\ \mathrm{mM}$$, $$[K^+]_{outside} = 5\ \mathrm{mM}$$, calculate the equilibrium potential for potassium ($$E_K) $$using the Nernst equation: $$E_{ion} = 62\ \mathrm{mV} \left( \log \frac{[ion]_{outside}}{[ion]_{inside}} \right). $$Which value is closest to the correct answer?

Accepted Answer

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

Question 3

What is the primary function of myelin sheaths in vertebrate neurons?

Accepted Answer

To insulate axons and speed up the conduction of action potentials via saltatory conduction

Question 4

Which of the following events occurs first during the generation of an action potential?

Accepted Answer

Voltage-gated Na+ channels open, causing rapid depolarization

Question 5

A neuron receives two excitatory postsynaptic potentials (EPSPs) in rapid succession at the same synapse. What is this phenomenon called, and what is its effect?

Accepted Answer

Temporal summation; it increases the likelihood of an action potential

Question 6

Which of the following best explains why the resting membrane potential of a neuron is closer to $$E_K$$ than $$E_{Na}$$?

Accepted Answer

There are more K+ leak channels than Na+ leak channels in the membrane

Question 7

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

Accepted Answer

Release of neurotransmitter into the synaptic cleft

Question 8

A mutation causes a neuron to lack functional voltage-gated Na+ channels. Which of the following would most likely occur?

Accepted Answer

The neuron would be unable to generate action potentials

Question 9

Which of the following statements about graded potentials and action potentials is correct?

Accepted Answer

Graded potentials can summate, while action potentials are all-or-none

Question 10

If a neuron’s membrane potential changes from $$-70\ \mathrm{mV} to$$ $$-80\ \mathrm{mV}$$, what has occurred?

Accepted Answer

Hyperpolarization

Question 11

Which of the following best describes the direction of information flow in a typical neuron?

Accepted Answer

Dendrite → Axon hillock → Axon → Synaptic terminal

Question 12

Which of the following is a property of an action potential that allows it to travel long distances without losing strength?

Accepted Answer

It is regenerated at each segment of the axon by voltage-gated ion channels

Question 13

Which glial cell type is responsible for myelinating axons in the peripheral nervous system (PNS)?

Accepted Answer

Schwann cells

Question 14

Which of the following would most likely result from blocking all K+ leak channels in a neuron?

Accepted Answer

The resting membrane potential would become more positive

Question 15

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

Accepted Answer

Voltage-gated Na+ channels become inactivated during the refractory period

Question 16

A drug blocks ligand-gated ion channels on the postsynaptic membrane. Which process would be directly affected?

Accepted Answer

Generation of postsynaptic potentials

Neurons, Synapses, and Signaling: Foundations of Nervous System Function

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