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Quiz: Neurons, Glia, and the Nervous System

Test your understanding of Chapter 1. Choose the best answer, then click Show Answer to check.

Question 1

Which part of a neuron receives incoming messages from other neurons and passes them toward the cell body?

  1. Axon
  2. Dendrite
  3. Axon terminal
  4. Myelin sheath
Show Answer

The correct answer is B. Dendrites are the short, branching "receivers" of a neuron, and they pass incoming messages toward the cell body. The axon (A) is a tempting choice because it is also a long extension, but it carries the neuron's own signal away from the cell body.

Concept Tested: Dendrite Bloom's Level: Remember

Question 2

Which pair of structures makes up the central nervous system?

  1. The brain and the cranial nerves
  2. The spinal cord and the spinal nerves
  3. The brain and all the nerves in the body
  4. The brain and the spinal cord
Show Answer

The correct answer is D. The central nervous system (CNS) is made of the brain and the spinal cord, the "headquarters" that processes information. Options A and B mix in nerves, which carry messages to and from the CNS and belong to the peripheral nervous system.

Concept Tested: Central Nervous System Bloom's Level: Remember

Question 3

Which glial cell makes myelin in the peripheral nervous system?

  1. Schwann cell
  2. Oligodendrocyte
  3. Astrocyte
  4. Microglia
Show Answer

The correct answer is A. Schwann cells make myelin in the PNS, and each one wraps a single segment of a single axon. Oligodendrocytes (B) also make myelin, but only in the CNS, where one cell can wrap segments of many different axons.

Concept Tested: Schwann Cell Bloom's Level: Remember

Question 4

Why does a myelinated axon carry signals faster than a thin unmyelinated axon?

  1. Myelin produces extra electrical charge that pushes the signal along.
  2. Myelin makes the axon shorter, so the signal has less distance to travel.
  3. Myelin insulates the axon so charge doesn't leak out, and the signal is renewed only at the nodes of Ranvier.
  4. Myelin carries the signal itself, so the axon no longer needs to.
Show Answer

The correct answer is C. Myelin is insulation: it keeps charge from leaking out, so the signal only needs to be renewed at the bare nodes of Ranvier and seems to jump from node to node. Option D is a common mix-up; myelin is a wrapping made by glial cells and does not carry the signal itself.

Concept Tested: Myelin Sheath Bloom's Level: Understand

Question 5

What is a concentration gradient, and why does it matter to a neuron?

  1. A difference in electric charge only, which lets the membrane block all ions
  2. A difference in how crowded a substance is in two places, which gives ions a "push" through open channels
  3. A protein pump in the membrane that moves ions one at a time
  4. A layer of fat around the axon that keeps ions from moving
Show Answer

The correct answer is B. A concentration gradient is a difference in how crowded a substance is in two places, and substances tend to move from crowded to less crowded when a path opens. That stored "push" is what drives ions through open channels. Option C describes a membrane protein (a pump), which helps rebuild gradients but is not the gradient itself.

Concept Tested: Concentration Gradient Bloom's Level: Understand

Question 6

Which statement best describes the job of the blood-brain barrier?

  1. It stops all substances, including glucose, from reaching brain cells.
  2. It is a layer of myelin that surrounds the whole brain.
  3. It is made by microglia that eat everything entering the brain.
  4. It lets in what the brain needs, such as glucose and oxygen, while blocking most germs and many other molecules.
Show Answer

The correct answer is D. The blood-brain barrier, formed mainly by tightly sealed cells lining the brain's capillaries and supported by astrocyte end-feet, is a selective filter. Option A is a common misunderstanding: the barrier is not a solid wall, and transport proteins actively carry glucose, the brain's main fuel, across it.

Concept Tested: Blood-Brain Barrier Bloom's Level: Understand

Question 7

A 30-year-old woman develops blurry vision and pain in one eye. Her MRI shows several white matter lesions in her brain and spinal cord, and her doctor diagnoses multiple sclerosis. Which cell's product is the main target of the immune attack in her disease?

  1. Myelin made by oligodendrocytes
  2. Myelin made by Schwann cells
  3. The cell bodies of sensory neurons in the skin
  4. The blood vessels that supply the eye
Show Answer

The correct answer is A. MS is an autoimmune attack on myelin in the central nervous system, and CNS myelin, including the optic nerve's, is made by oligodendrocytes. Option B is the most tempting distractor, but Schwann cells make myelin in the peripheral nervous system, which is the target in a different disease, Guillain-Barré syndrome.

Concept Tested: Multiple Sclerosis Bloom's Level: Apply

Question 8

Maya touches a hot pan and jerks her hand away. Which neuron type carries the command from her spinal cord to her arm muscles?

  1. Sensory neuron
  2. Interneuron
  3. Motor neuron
  4. Microglia
Show Answer

The correct answer is C. Motor neurons carry commands from the CNS out to muscles. Sensory neurons (A) handle the first step, carrying the "hot!" message from the skin into the spinal cord, and interneurons (B) connect neurons inside the CNS, but neither one sends commands to muscles.

Concept Tested: Motor Neuron Bloom's Level: Apply

Question 9

Two patients both have an immune attack on myelin. Patient 1 has blurry vision in one eye and lesions on a brain MRI. Patient 2 has weakness that climbs from the feet up the legs, a normal brain and spinal cord MRI, and slowed signals in the nerves of the arms and legs. What best explains the difference?

  1. Patient 1 has damaged axon terminals, while Patient 2 has damaged dendrites.
  2. Patient 1's disease affects CNS myelin made by oligodendrocytes, while Patient 2's affects PNS myelin made by Schwann cells.
  3. Both patients have the same disease, but Patient 2's is milder.
  4. Patient 1's disease affects microglia, while Patient 2's affects astrocytes.
Show Answer

The correct answer is B. Brain lesions point to the CNS (as in multiple sclerosis), while a normal brain and spinal cord MRI with slowed limb nerves points to the PNS (as in Guillain-Barré syndrome). Option C is tempting, but the two patterns come from different locations and different myelin-making cells, not from a difference in severity.

Concept Tested: Peripheral Nervous System Bloom's Level: Analyze

Question 10

In the Neuron Explorer, removing myelin from 2 segments makes the signal arrive late, but removing it from 3 segments blocks it completely. What does this pattern show?

  1. Any loss of myelin always stops a signal.
  2. Myelin loss has no effect until the axon terminals are damaged.
  3. The nodes of Ranvier inside the damaged stretch keep the signal at full strength.
  4. A longer bare stretch lets more charge leak out, so the signal can fade below the level needed to be renewed at the next healthy node.
Show Answer

The correct answer is D. In a bare stretch, charge leaks out and the signal weakens as it goes. A short stretch only slows it, but a longer one lets it fade so much that the next healthy node cannot renew it. Option A ignores the fact that small patches of damage can slow a signal without stopping it, which helps explain why MS symptoms vary.

Concept Tested: Node of Ranvier Bloom's Level: Analyze