Q: Which of the following best describes the role of the Na\textsuperscript{+}-K\textsuperscript{+} pump in maintaining the resting membrane potential of a neuron?

It actively transports 3 Na\textsuperscript{+} out and 2 K\textsuperscript{+} in, creating a net negative charge inside the cell.

Q: During the depolarization phase of an action potential, which ion channel opens and what is the direction of ion movement?

Voltage-gated Na\textsuperscript{+} channels open, allowing Na\textsuperscript{+} to enter the cell.

Q: If a ligand-gated Ca\textsuperscript{2+} channel opens, what causes Ca\textsuperscript{2+} ions to move through the channel?

Both the concentration and electrical gradients favor Ca\textsuperscript{2+} influx.

Q: During the repolarization phase of the action potential, which event occurs?

Voltage-gated K\textsuperscript{+} channels open and K\textsuperscript{+} leaves the cell.

Question 1

Which of the following best describes the role of the Na	extsuperscript{+}-K	extsuperscript{+} pump in maintaining the resting membrane potential of a neuron?

Accepted Answer

It actively transports 3 Na	extsuperscript{+} out and 2 K	extsuperscript{+} in, creating a net negative charge inside the cell.

Question 2

During the depolarization phase of an action potential, which ion channel opens and what is the direction of ion movement?

Accepted Answer

Voltage-gated Na	extsuperscript{+} channels open, allowing Na	extsuperscript{+} to enter the cell.

Question 3

Which gradients pull K	extsuperscript{+} ions out of the cell according to the diagram?

Accepted Answer

Only the concentration gradient.

Question 4

What is the main difference between leak channels and voltage-gated channels in neurons?

Accepted Answer

Leak channels are always open, while voltage-gated channels open in response to changes in membrane potential.

Question 5

If a ligand-gated Ca	extsuperscript{2+} channel opens, what causes Ca	extsuperscript{2+} ions to move through the channel?

Accepted Answer

Both the concentration and electrical gradients favor Ca	extsuperscript{2+} influx.

Question 6

Which of the following best explains why the inside of a neuron is negatively charged at rest?

Accepted Answer

Large negatively charged proteins are trapped inside the cell and K	extsuperscript{+} leak channels allow K	extsuperscript{+} to leave.

Question 7

A neuron receives multiple excitatory postsynaptic potentials (EPSPs) at different locations on its dendrites at the same time. What is this phenomenon called?

Accepted Answer

Spatial summation

Question 8

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

Accepted Answer

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

Question 9

What would happen to the resting membrane potential if extracellular K	extsuperscript{+} concentration increased significantly?

Accepted Answer

The membrane potential would become less negative (depolarize).

Question 10

During the repolarization phase of the action potential, which event occurs?

Accepted Answer

Voltage-gated K	extsuperscript{+} channels open and K	extsuperscript{+} leaves the cell.

Question 11

A patient with a mutation in the Na	extsuperscript{+}-K	extsuperscript{+} pump has reduced pump activity. What is a likely consequence for their neurons?

Accepted Answer

Neurons are less able to fire action potentials due to depolarization failure.

Question 12

Which of the following is TRUE about ligand-gated ion channels?

Accepted Answer

They open when a specific chemical binds to them.

Question 13

If acetylcholine binds to its receptor on a postsynaptic neuron, what is the most likely immediate effect?

Accepted Answer

Opening of ligand-gated Na	extsuperscript{+} channels, causing depolarization.

Question 14

Which of the following best describes the refractory period in a neuron?

Accepted Answer

The period when voltage-gated Na	extsuperscript{+} channels are inactivated and cannot reopen immediately.

Question 15

A neuron is exposed to a toxin that blocks K	extsuperscript{+} leak channels. What is the most likely effect?

Accepted Answer

The resting membrane potential becomes less negative.

Question 16

Which of the following is a correct sequence of events during an action potential?

Accepted Answer

Depolarization, Na	extsuperscript{+} channels close, K	extsuperscript{+} channels open, repolarization.

Question 17

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

Accepted Answer

Increasing the diameter of the axon and adding myelin.

Question 18

A neuron receives repeated EPSPs at the same synapse in rapid succession. What is this called?

Accepted Answer

Temporal summation

Question 19

Which of the following is TRUE regarding the movement of Na	extsuperscript{+} ions when voltage-gated Na	extsuperscript{+} channels open?

Accepted Answer

Na	extsuperscript{+} moves into the cell due to both concentration and electrical gradients.

Nervous System Physiology: Membrane Potentials and Ion Channels

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