$$3\mathrm{Na}^+_{\text{out}} + 2\mathrm{K}^+_{\text{in}} + \text{ATP} \rightarrow$$

Question 1

Which of the following best describes the role of the myelin sheath in neuronal signaling?

Accepted Answer

It insulates the axon, allowing action potentials to propagate more quickly by enabling signals to 'hop' between nodes of Ranvier.

Question 2

What is the primary function of Schwann cells in the peripheral nervous system?

Accepted Answer

They wrap around axons to form the myelin sheath, insulating the axon.

Question 3

During the resting potential of a neuron, which of the following statements is TRUE?

Accepted Answer

The membrane potential is negative because there is high Na$$^+$$ outside and high K$$^+$$ inside the cell.

Question 4

Which equation best represents the action of the sodium-potassium pump in maintaining the resting potential?

Accepted Answer

$$3\mathrm{Na}^+_{	ext{out}} + 2\mathrm{K}^+_{	ext{in}} + 	ext{ATP} ightarrow$$

Question 5

A stimulus causes Na$$^+$$ channels to open at the axon hillock. What is the immediate effect on the membrane potential?

Accepted Answer

The membrane potential becomes less negative (depolarization).

Question 6

Which phase of the action potential is characterized by the closing of Na$$^+$$ channels and the opening of K$$^+$$ channels?

Accepted Answer

Peak phase

Question 7

Multiple sclerosis (MS) damages the myelin sheath. What is the most likely consequence for nerve signal transmission?

Accepted Answer

Action potentials fail to propagate efficiently, leading to slower or blocked nerve signals.

Question 8

During muscle fatigue, many sodium-potassium pumps stop working. What is the result?

Accepted Answer

Na$$^+$$ and K$$^+$$ ions are in the 'wrong' places, disrupting the resting potential and action potential propagation.

Question 9

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

Accepted Answer

The refractory period prevents Na$$^+$$ channels from reopening immediately after an action potential.

Question 10

Which of the following events occurs during the falling phase (repolarization) of an action potential?

Accepted Answer

K$$^+$$ ions diffuse out of the cell.

Question 11

A neuron receives a stimulus that is not strong enough to reach the threshold. What will happen?

Accepted Answer

The membrane potential will change slightly, but no action potential will be generated.

Question 12

Which of the following best describes the propagation of an action potential along a myelinated axon?

Accepted Answer

Saltatory conduction, where the action potential 'hops' from one node of Ranvier to the next.

Question 13

Which of the following is TRUE about the concentration of ions during the resting potential?

Accepted Answer

Na$$^+$$ concentration is higher outside the cell, and K$$^+$$ concentration is higher inside the cell.

Question 14

What is the main driving force for the movement of ions across a neuron's membrane?

Accepted Answer

The difference in ion concentration and electrical charge across the membrane.

Question 15

Which of the following best describes the role of dendrites in a neuron?

Accepted Answer

They receive incoming messages and direct them towards the cell body.

Question 16

During the recovery (refractory) phase of an action potential, which process restores the resting potential?

Accepted Answer

Action of the sodium-potassium pump using ATP.

Question 17

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

Accepted Answer

Stimulation → Depolarization → Peak → Repolarization → Recovery

Question 18

If a neuron is exposed to a drug that blocks all K$$^+$$ channels, what would be the most likely effect on the action potential?

Accepted Answer

The neuron would be unable to repolarize, prolonging the action potential.

Question 19

Which of the following best explains why the sodium-potassium pump requires ATP?

Accepted Answer

It moves Na$$^+$$ and K$$^+$$ ions against their concentration gradients.

Nerve Cells, Membrane Potentials, and Action Potentials: Study Notes for GOB Chemistry

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