Q: Which of the following equations correctly represents the action of the Na+/K+ ATPase pump?

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

Question 1

Which of the following best explains why the resting membrane potential (RMP) of a neuron is negative?

Accepted Answer

The membrane is more permeable to K+ than Na+ at rest, and the Na+/K+ pump moves 3 Na+ out for every 2 K+ in.

Question 2

Which glial cell type is responsible for forming myelin sheaths in the central nervous system (CNS)?

Accepted Answer

Oligodendrocytes

Question 3

A patient has a demyelinating disease affecting the CNS. Which process is most directly impaired?

Accepted Answer

Saltatory conduction along axons

Question 4

During the depolarizing phase of an action potential, which event occurs first?

Accepted Answer

Voltage-gated Na+ channels open

Question 5

Which of the following equations correctly represents the action of the Na+/K+ ATPase pump?

Accepted Answer

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

Question 6

Which of the following best describes the absolute refractory period?

Accepted Answer

A period when Na+ channels are open and a second action potential cannot be generated

Question 7

A graded potential is most likely to occur in which part of a neuron?

Accepted Answer

Dendrite

Question 8

Which of the following statements about action potentials is TRUE?

Accepted Answer

They are all-or-none events and do not decrease in size with distance.

Question 9

If a neurotransmitter causes the opening of chemically-gated Cl- channels on the postsynaptic membrane, what is the likely result?

Accepted Answer

A hyperpolarization of the postsynaptic membrane (IPSP)

Question 10

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

Accepted Answer

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

Question 11

A neuron receives multiple excitatory and inhibitory inputs at its dendrites. What determines whether it will fire an action potential?

Accepted Answer

The sum of EPSPs and IPSPs at the axon hillock reaching threshold

Question 12

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

Accepted Answer

Anchoring neurons to capillaries and regulating nutrient exchange

Question 13

Which type of glial cell is primarily responsible for immune defense in the CNS?

Accepted Answer

Microglial cell

Question 14

Which of the following best describes saltatory conduction?

Accepted Answer

Action potentials jump from one node of Ranvier to the next, increasing conduction speed.

Question 15

A neuron is exposed to a toxin that blocks voltage-gated Na+ channels. What is the most immediate effect?

Accepted Answer

The neuron cannot generate an action potential.

Question 16

Which of the following neurotransmitters is classified as a biogenic amine?

Accepted Answer

Dopamine

Question 17

Which of the following is a direct effect of neurotransmitter binding to its receptor on the postsynaptic membrane?

Accepted Answer

Immediate opening of an ion channel

Question 18

Which of the following best describes the difference between graded potentials and action potentials?

Accepted Answer

Graded potentials decrease in magnitude with distance, while action potentials do not.

Question 19

Which of the following is NOT a mechanism for terminating neurotransmitter action at a synapse?

Accepted Answer

Continuous stimulation of the postsynaptic membrane

Membrane Transport & Excitable Cells: Neuron Physiology and Synaptic Transmission

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