Question 1

Which of the following best describes the function of the axon hillock in a neuron?

Accepted Answer

It integrates incoming signals and initiates the action potential if threshold is reached.

Question 2

Which of the following ions is most responsible for the depolarization phase of the action potential in neurons?

Accepted Answer

Sodium (Na⁺)

Question 3

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

Accepted Answer

It pumps 3 Na⁺ out and 2 K⁺ in, using ATP, maintaining the concentration gradients.

Question 4

Which of the following best defines the 'all-or-none' law of action potentials?

Accepted Answer

If threshold is reached, an action potential will fire at full amplitude; if not, none will occur.

Question 5

Which adaptation increases the speed of action potential conduction in vertebrate neurons?

Accepted Answer

Myelination of axons

Question 6

What is the main function of oligodendrocytes in the central nervous system?

Accepted Answer

They form the myelin sheath around axons.

Question 7

During the refractory period, why can't a neuron fire another action potential?

Accepted Answer

Voltage-gated sodium channels are inactivated and cannot reopen immediately.

Question 8

Which of the following best describes the resting membrane potential of a typical neuron?

Accepted Answer

It is the voltage across the membrane when the neuron is not transmitting a signal, usually around $$-70\ \mathrm{mV}.$$

Question 9

Which of the following is NOT a characteristic of neurons?

Accepted Answer

Contractility

Question 10

Which type of glial cell is responsible for forming the blood-brain barrier?

Accepted Answer

Astrocytes

Question 11

What is the effect of myelination on the conduction of action potentials?

Accepted Answer

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

Question 12

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

Accepted Answer

The refractory period prevents the backward movement of the action potential.

Question 13

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

Accepted Answer

Depolarization → Repolarization → Hyperpolarization → Resting state

Question 14

Which of the following best describes depolarization in a neuron?

Accepted Answer

The inside of the neuron becomes less negative (more positive) due to Na⁺ influx.

Question 15

Which of the following is a key difference between Schwann cells and oligodendrocytes?

Accepted Answer

Schwann cells myelinate axons in the peripheral nervous system, while oligodendrocytes myelinate axons in the central nervous system.

Question 16

Which of the following equations correctly represents the Nernst equation for calculating the equilibrium potential for an ion?

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{outside}}{[ion]_{inside}} \right)$$

Question 17

A patient is diagnosed with multiple sclerosis, a disease that damages myelin sheaths. Which of the following symptoms is most likely to result from this condition?

Accepted Answer

Slowed or blocked transmission of nerve impulses

Question 18

Which of the following best describes hyperpolarization in a neuron?

Accepted Answer

The membrane potential becomes more negative than the resting potential.

Question 19

Which of the following is NOT a function of glial cells?

Accepted Answer

Generating action potentials

Question 20

Which of the following adaptations would most likely be found in a fast-conducting neuron?

Accepted Answer

Large axon diameter and presence of myelination

Neurons: Structure, Function, and Action Potentials

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