Q: Which equation correctly represents the action of the sodium-potassium pump in neurons?

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

Question 1

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

Accepted Answer

They maintain the blood-brain barrier and regulate the chemical environment of the brain.

Question 2

A patient presents with muscle weakness and tingling in the legs after a flu-like illness. Which nervous system disorder is most likely responsible, and what is its primary pathological feature?

Accepted Answer

Guillain-Barre Syndrome; inflammatory demyelination of peripheral nerves.

Question 3

Which equation correctly represents the action of the sodium-potassium pump in neurons?

Accepted Answer

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

Question 4

Which of the following is TRUE regarding graded potentials in neurons?

Accepted Answer

They vary in magnitude depending on stimulus strength and decrease in intensity with distance.

Question 5

A neuron receives multiple simultaneous excitatory inputs at different locations on its dendrites. What is this phenomenon called, and what is its effect?

Accepted Answer

Spatial summation; increases the likelihood of reaching threshold for an action potential.

Question 6

Which type of glial cell is responsible for myelinating axons in the peripheral nervous system (PNS)?

Accepted Answer

Schwann cells (Neurolemmocytes)

Question 7

During the propagation of an action potential along a myelinated axon, which process allows the electrical signal to 'jump' from node to node?

Accepted Answer

Saltatory propagation

Question 8

Which of the following best explains why action potentials are nondecremental?

Accepted Answer

They are regenerated at each segment of the axon by voltage-gated channels.

Question 9

Which neurotransmitter is released at all neuromuscular junctions with skeletal muscle fibers?

Accepted Answer

Acetylcholine (ACh)

Question 10

A neuron is at rest with a membrane potential of $$-70\ \mathrm{mV}. $$What is the minimum depolarization required to reach threshold and trigger an action potential?

Accepted Answer

$$10 to$$ $$15\ \mathrm{mV}$$

Question 11

Which of the following best describes the difference between white matter and gray matter in the CNS?

Accepted Answer

White matter contains myelinated axons; gray matter contains unmyelinated axons and cell bodies.

Question 12

Which of the following is a direct effect of excitatory neurotransmitters on the postsynaptic membrane?

Accepted Answer

Depolarization, promoting the generation of action potentials.

Question 13

Which type of neuronal circuit is responsible for producing rhythmic, repeated activity such as breathing?

Accepted Answer

Reverberating circuit

Question 14

What is the primary reason that nerve regeneration in the CNS is limited compared to the PNS?

Accepted Answer

Oligodendrocytes secrete growth-inhibitory molecules and astrocytes produce scar tissue.

Question 15

Which of the following best describes the role of microglia in the CNS?

Accepted Answer

They act as immune cells, cleaning up debris and pathogens.

Question 16

Which of the following is TRUE about the refractory period of an action potential?

Accepted Answer

During the relative refractory period, a stronger-than-normal stimulus can initiate another action potential.

Question 17

Which of the following best explains why myelinated axons conduct action potentials faster than unmyelinated axons?

Accepted Answer

Myelin allows action potentials to jump between nodes of Ranvier, reducing the number of depolarizations required.

Question 18

Which of the following is a function of ependymal cells in the CNS?

Accepted Answer

They produce and circulate cerebrospinal fluid.

Question 19

Which of the following best describes the effect of inhibitory neurotransmitters on the postsynaptic membrane?

Accepted Answer

They cause hyperpolarization and suppress action potentials.

Nervous System: Structure, Function, and Cellular Components (Chapter 11 Study Notes)

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