Membrane Potentials and Action Potentials: Interactive Learning Quizzes

Question 1

Which electrophysiological technique allows for the real-time measurement of membrane potentials and currents?

Accepted Answer

Patch clamping

Answer

Western blotting

Answer

Immunohistochemistry

Answer

Flow cytometry

Question 2

Which ion contributes primarily to the resting membrane potential of a neuron?

Accepted Answer

Potassium (K+)

Answer

Sodium (Na+)

Answer

Calcium (Ca2+)

Answer

Chloride (Cl-)

Question 3

Which of the following describes the refractory period of an action potential?

Accepted Answer

A period during which the neuron cannot generate another action potential

Answer

A period during which the neuron is hypersensitive to stimuli

Answer

A period during which the neuron's membrane potential remains reversed

Answer

A period during which the neuron's membrane is depolarized

Question 4

What is the primary role of voltage-gated sodium channels in an action potential?

Accepted Answer

To allow sodium ions to enter the neuron, leading to depolarization

Answer

To allow sodium ions to exit the neuron, causing repolarization

Answer

To allow potassium ions to enter the neuron, leading to depolarization

Answer

To allow potassium ions to exit the neuron, causing repolarization

Question 5

What is the term for the period immediately after an action potential during which the neuron cannot generate another action potential?

Accepted Answer

Absolute refractory period

Answer

Relative refractory period

Answer

Hyperpolarization phase

Answer

Depolarization phase

Question 6

What is the function of hyperpolarization in an action potential?

Accepted Answer

To bring the membrane potential below the resting membrane potential

Answer

To bring the membrane potential above the threshold potential

Answer

To reverse the polarity of the membrane potential

Answer

To prevent the generation of consecutive action potentials

Question 7

Which ion plays a primary role in repolarizing the neuron after an action potential?

Accepted Answer

Potassium (K+)

Answer

Sodium (Na+)

Answer

Calcium (Ca2+)

Answer

Chloride (Cl-)

Question 8

What is the term for the propagation of an action potential along the axon?

Accepted Answer

Saltatory conduction

Answer

Continuous conduction

Answer

Ephaptic conduction

Answer

Graded conduction

Question 9

How do ion channels contribute to the resting membrane potential of a neuron?

Accepted Answer

They allow ions to move passively down their concentration gradients.

Answer

They actively pump ions against their concentration gradients.

Answer

They generate action potentials.

Question 10

Which ion is chiefly responsible for establishing the resting membrane potential?

Accepted Answer

Potassium

Answer

Sodium

Answer

Chloride

Answer

Calcium

Question 11

Which type of ion channel is primarily responsible for the rapid depolarization phase of an action potential?

Accepted Answer

Voltage-gated sodium channels

Answer

Voltage-gated potassium channels

Answer

Leak channels

Answer

Ligand-gated ion channels

Question 12

Which drug is known to block voltage-gated sodium channels?

Accepted Answer

Tetrodotoxin

Answer

Strychnine

Answer

Botulinum toxin

Answer

Curare

Question 13

What is the significance of the Nernst equation in the study of membrane potentials?

Accepted Answer

Predicts the equilibrium potential of an ion across a membrane

Answer

Determines the magnitude of the action potential

Answer

Calculates the leak current through ion channels

Answer

Describes the relationship between membrane capacitance and membrane resistance

Question 14

How does the sodium-potassium pump contribute to the resting membrane potential?

Accepted Answer

Establishes concentration gradients of sodium and potassium ions across the membrane

Answer

Directly depolarizes the membrane by pumping sodium ions out of the cell

Answer

Hyperpolarizes the membrane by pumping potassium ions into the cell

Answer

Does not significantly contribute to the resting membrane potential

Question 15

What is the primary function of ligand-gated ion channels?

Accepted Answer

Allow ion movement across the membrane in response to specific ligand binding

Answer

Generate action potentials

Answer

Regulate the resting membrane potential

Answer

Pump ions against concentration gradients

Question 16

How do neurotransmitters affect membrane potentials and action potentials?

Accepted Answer

Neurotransmitters bind to receptors on the neuron's membrane, causing ion channels to open or close, changing ion flow and influencing membrane potential.

Answer

Neurotransmitters directly impact the sodium-potassium pump, which maintains the resting membrane potential.

Answer

Neurotransmitters only affect membrane potentials, not action potentials.

Answer

Neurotransmitters have no effect on membrane potentials or action potentials.

Question 17

Which ion channel is responsible for the rapid increase in membrane potential during the depolarization phase of an action potential?

Accepted Answer

Voltage-gated sodium channel

Answer

Sodium-potassium pump

Answer

Voltage-gated potassium channel

Question 18

Which ion establishes and maintains the resting membrane potential of a neuron?

Accepted Answer

Potassium (K+)

Answer

Chloride (Cl-)

Answer

Sodium (Na+)

Answer

Calcium (Ca2+)

Question 19

During which phase of an action potential do sodium channels open and cause depolarization?

Accepted Answer

Rising phase (Depolarization)

Answer

Falling phase (Repolarization

Answer

Plateau phase

Answer

Refractory period

Question 20

What is the primary role of the sodium-potassium pump in neuronal function?

Accepted Answer

Maintain the electrochemical gradient of sodium and potassium ions across the membrane

Answer

Generate action potentials

Answer

Control ion concentrations in the cytoplasm

Answer

Regulate neurotransmitter release

Question 21

Which type of ion channel opens and closes in response to changes in membrane potential?

Accepted Answer

Voltage-gated channels

Answer

Ligand-gated channels

Answer

Mechanosensitive channels

Answer

Leak channels

Question 22

What is the function of the refractory period following an action potential?

Accepted Answer

Prevent the neuron from firing another action potential

Answer

Shorten the duration of the action potential

Answer

Increase the threshold potential

Answer

Amplify the action potential

Question 23

Which ion influx triggers neurotransmitter release at the presynaptic membrane?

Accepted Answer

Calcium (Ca2+)

Answer

Chloride (Cl-)

Answer

Potassium (K+)

Answer

Sodium (Na+)

Question 24

What is the primary function of the myelin sheath surrounding axons?

Accepted Answer

Increase the speed of action potential conduction

Answer

Control the direction of action potential travel

Answer

Amplify the action potential signal

Answer

Prevent action potential propagation

Question 25

Which ion flux is primarily responsible for the afterhyperpolarization phase of an action potential?

Accepted Answer

Potassium (K+) efflux

Answer

Sodium (Na+) efflux

Answer

Calcium (Ca2+) efflux

Answer

Chloride (Cl-) efflux

Question 26

What is the approximate value of the resting membrane potential in a typical neuron?

Accepted Answer

-70 mV

Answer

-50 mV

Answer

-110 mV

Answer

-90 mV

Question 27

Which phase of the action potential is characterized by a rapid influx of sodium ions into the cell?

Accepted Answer

Depolarization

Answer

Refractory period

Answer

Undershoot

Answer

Hyperpolarization

Question 28

What is the absolute refractory period of a neuron?

Accepted Answer

The time during which the neuron cannot generate another action potential.

Answer

The time during which the neuron is repolarizing.

Answer

The time during which the neuron is most likely to generate an action potential.

Question 29

Which of the following neurotransmitters is known to cause hyperpolarization of the postsynaptic neuron?

Accepted Answer

GABA

Answer

Glutamate

Answer

Acetylcholine

Answer

Dopamine

Question 30

What is the primary function of the myelin sheath in saltatory conduction?

Accepted Answer

To insulate the axon, enabling action potentials to propagate more rapidly (jump) between nodes of Ranvier.

Answer

To generate action potentials.

Answer

To slow down the propagation of action potentials.

Question 31

What is the primary function of voltage-gated ion channels in neurons?

Accepted Answer

To regulate the flow of ions across the cell membrane, controlling membrane potential and excitability.

Answer

To receive neurotransmitters.

Answer

To generate neurotransmitters.

Question 32

Which of the following is the primary mechanism by which neurons maintain a resting membrane potential?

Accepted Answer

Leakage of K+ ions out of the cell

Answer

Inward movement of Cl- ions

Answer

Pumping of Na+ ions out of the cell

Answer

Efflux of Ca2+ ions from the cell

Question 33

During an action potential, the membrane becomes more ____ to Na+ ions.

Accepted Answer

Permeable

Answer

Transiently impermeable

Answer

Impermeable

Answer

Less permeable

Question 34

Which of the following ions is responsible for the repolarization phase of an action potential?

Accepted Answer

K+

Answer

Na+

Answer

Ca2+

Answer

Cl-

Question 35

The refractory period of a neuron is characterized by ____.

Accepted Answer

Inability to generate an action potential in the same region

Answer

Enhanced neuronal excitability

Answer

Increased release of neurotransmitters

Question 36

The threshold potential of a neuron is the minimum level of depolarization required to ____.

Accepted Answer

Trigger an action potential

Answer

Maintain a resting membrane potential

Answer

Cause hyperpolarization

Question 37

The absolute refractory period refers to the ____.

Accepted Answer

Period of time during which a neuron is completely unresponsive to further stimulation

Answer

Period of time during which a neuron is more likely to generate an action potential

Answer

Period of time during which a neuron can generate an action potential with reduced amplitude

Question 38

Which of the following is a neurotoxin that blocks sodium channels?

Accepted Answer

Tetrodotoxin

Answer

Botulinum toxin

Answer

Conotoxins

Answer

Strychnine

Question 39

The opening of chemically-gated ion channels is typically caused by   ____.

Accepted Answer

Binding of neurotransmitters to receptors

Answer

Mechanical stimuli

Answer

Temperature changes

Answer

Changes in membrane potential

Question 40

Which of the following factors does NOT contribute to the resting membrane potential of a neuron?

Accepted Answer

Intracellular sodium concentration

Answer

Potassium leak channels

Answer

Sodium-potassium pump activity

Answer

Chloride ion distribution

Question 41

Which ion channel is primarily responsible for the repolarization phase of an action potential?

Accepted Answer

Voltage-gated potassium channels

Answer

Chloride channels

Answer

Leak potassium channels

Answer

Voltage-gated sodium channels

Question 42

What is meant by the refractory period of a neuron?

Accepted Answer

A period of time after an action potential when the neuron is less likely to fire another action potential

Answer

A period of time before an action potential when the neuron is more likely to fire

Question 43

What is the role of the sodium-potassium pump in maintaining the resting membrane potential?

Accepted Answer

To actively transport 3 sodium ions out of the cell and 2 potassium ions into the cell, using ATP hydrolysis

Answer

To passively transport 3 sodium ions into the cell and 2 potassium ions out of the cell

Answer

To generate an electrochemical gradient for sodium and potassium ions

Question 44

Which of the following neurotransmitters causes hyperpolarization of the postsynaptic neuron?

Accepted Answer

GABA

Answer

Dopamine

Answer

Glutamate

Answer

Acetylcholine

Question 45

What is the primary function of the myelin sheath in neurons?

Accepted Answer

To increase the speed of action potential propagation by saltatory conduction

Answer

To regulate the release of neurotransmitters

Answer

To prevent the loss of ions during action potential propagation

Question 46

What is the role of the axon hillock in action potential initiation?

Accepted Answer

It is the site where voltage-gated sodium channels are densely clustered and the action potential is most likely to be initiated

Answer

It is the site of synaptic integration

Answer

It is the site of neurotransmitter release

Question 47

A neuron at rest receives a stimulus that causes a small depolarization, but this depolarization does not reach the threshold potential. What is the most likely outcome?

Accepted Answer

The membrane potential will passively return to its resting value.

Answer

An action potential will be initiated.

Answer

The sodium-potassium pump will temporarily cease functioning.

Question 48

During the repolarization phase of an action potential, the membrane potential becomes more negative. Which of the following directly contributes to this repolarization?

Accepted Answer

The outward flow of potassium ions.

Answer

The activity of the sodium-potassium pump.

Answer

The closure of sodium channels.

Answer

The inward flow of sodium ions.

Question 49

What is the primary role of myelin in the propagation of action potentials?

Accepted Answer

Myelin increases the speed of conduction by enabling saltatory conduction.

Answer

Myelin generates the action potential at the nodes of Ranvier.

Answer

Myelin slows down conduction by insulating the axon.

Question 50

The resting membrane potential of a neuron is primarily established by:

Accepted Answer

The unequal permeability of the membrane to potassium and sodium ions.

Answer

The action of voltage-gated sodium channels.

Answer

The equilibrium potential of chloride ions.

Question 51

What characterizes the absolute refractory period of a neuron?

Accepted Answer

During this period, the neuron is incapable of generating another action potential, regardless of stimulus strength.

Answer

The neuron can generate another action potential, but only with a stronger stimulus.

Answer

This period corresponds to the hyperpolarization phase following an action potential.

Question 52

A drug that blocks voltage-gated calcium channels would most directly interfere with which of the following processes?

Accepted Answer

Neurotransmitter release at the synapse.

Answer

Action potential propagation along the axon.

Answer

Reuptake of neurotransmitters by the presynaptic neuron.

Answer

Maintenance of the resting membrane potential.

Question 53

The Nernst equation is primarily used to calculate:

Accepted Answer

The equilibrium potential for a single ion.

Answer

The resting membrane potential of a neuron.

Answer

The threshold potential for an action potential.

Answer

The speed of action potential propagation.

Question 54

Hyperkalemia, a condition characterized by elevated extracellular potassium levels, would likely lead to:

Accepted Answer

Depolarization of neurons.

Answer

Hyperpolarization of neurons.

Answer

Increased neuronal excitability.

Answer

Enhanced action potential conduction.

Question 55

Which of the following is a characteristic of graded potentials but NOT action potentials?

Accepted Answer

The amplitude of graded potentials can vary depending on the strength of the stimulus.

Answer

Graded potentials are initiated by the opening of voltage-gated channels.

Answer

Graded potentials are all-or-none events.

Question 56

The after-hyperpolarization phase of an action potential is primarily caused by:

Accepted Answer

The continued outward flow of potassium ions even after the membrane potential has fallen below the resting potential.

Answer

The influx of chloride ions into the neuron.