Question 1

Which of the following best describes the function of astrocytes in the central nervous system (CNS)?

Accepted Answer

They brace and anchor neurons to capillaries, forming the blood-brain barrier.

Question 2

A patient has a demyelinating disease affecting the CNS. Which type of neuroglial cell is most likely impaired?

Accepted Answer

Oligodendrocytes

Question 3

During the resting membrane potential of a neuron, which of the following is true?

Accepted Answer

Potassium ions ($$\mathrm{K^+}) $$are in higher concentration inside the cell.

Question 4

Which of the following best explains why action potentials travel faster in myelinated axons?

Accepted Answer

Myelin sheaths allow for saltatory conduction, where impulses jump between nodes of Ranvier.

Question 5

A neuron receives a stimulus that causes depolarization. What is the immediate effect on the membrane potential?

Accepted Answer

Sodium channels open, allowing $$\mathrm{Na^+} to $$enter the cell, making the inside more positive.

Question 6

Which of the following is a function of microglia in the CNS?

Accepted Answer

Phagocytosing dead cells and bacteria

Question 7

If a neuron is unable to respond to a second stimulus, no matter how strong, it is said to be in which phase?

Accepted Answer

Absolute refractory period

Question 8

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

Accepted Answer

It pumps three sodium ions out and two potassium ions in, using ATP.

Question 9

A drug blocks the reuptake and enzymatic degradation of acetylcholine at the neuromuscular junction. What is the most likely effect?

Accepted Answer

Muscle contraction will be prolonged due to continued stimulation.

Question 10

Which of the following is true regarding graded potentials?

Accepted Answer

Their magnitude varies with the strength of the stimulus.

Question 11

Which of the following best describes the function of Schwann cells?

Accepted Answer

They form myelin sheaths around axons in the peripheral nervous system.

Question 12

A patient has a tumor composed of rapidly dividing glial cells in the brain. Which property of neuroglia explains this?

Accepted Answer

Neuroglia can undergo cell division, unlike most neurons.

Question 13

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

Accepted Answer

Depolarization, repolarization, hyperpolarization

Question 14

Which of the following is a characteristic of the 'all-or-none' principle of action potentials?

Accepted Answer

Once threshold is reached, an action potential always occurs with the same magnitude.

Question 15

Which of the following best describes the function of ependymal cells?

Accepted Answer

They line the central cavities of the brain and spinal cord and help circulate cerebrospinal fluid.

Question 16

A neuron is exposed to a toxin that keeps voltage-gated sodium channels open. What is the most likely effect on the neuron's membrane potential?

Accepted Answer

The membrane will remain depolarized, preventing repolarization.

Question 17

Which of the following is NOT a function of the peripheral nervous system (PNS)?

Accepted Answer

Interpreting incoming sensory information

Question 18

Which of the following best describes the direction of impulse conduction in a typical neuron?

Accepted Answer

From dendrites to cell body to axon

Question 19

Which of the following is true regarding synaptic transmission at a chemical synapse?

Accepted Answer

Neurotransmitters are quickly removed from the synaptic cleft after binding to receptors.

Question 20

A patient is given a drug that blocks potassium channels in neurons. What effect will this have on the action potential?

Accepted Answer

It will prolong repolarization, making the action potential last longer.

Nerve Impulses and the Nervous System: Structure and Function

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