Q: Which equation correctly represents the Nernst equation for calculating the equilibrium potential of an ion across a membrane?

$$E = \frac{RT}{zF} \ln \left( \frac{[\text{ion}]_{\text{out}}}{[\text{ion}]_{\text{in}}} \right)$$

Question 1

Which of the following best describes the role of oligodendrocytes in the central nervous system (CNS)?

Accepted Answer

They form myelin sheaths around axons in the CNS, increasing conduction velocity.

Question 2

A patient presents with muscle weakness and slowed nerve conduction. Which glial cell type is most likely affected, and what is its primary function?

Accepted Answer

Oligodendrocytes; they myelinate axons in the CNS to speed up action potential conduction.

Question 3

Which equation correctly represents the Nernst equation for calculating the equilibrium potential of an ion across a membrane?

Accepted Answer

$$E = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{out}}}{[	ext{ion}]_{	ext{in}}} ight)$$

Question 4

During the repolarization phase of an action potential, which ion movement is primarily responsible for returning the membrane potential toward its resting value?

Accepted Answer

Efflux of K$$^+$$ ions

Question 5

Which of the following best explains why action potentials are unidirectional along an axon?

Accepted Answer

The absolute refractory period prevents the backward propagation of action potentials.

Question 6

A neuron receives simultaneous excitatory and inhibitory inputs. Which of the following best describes the outcome at the axon hillock?

Accepted Answer

The summation of EPSPs and IPSPs determines whether the membrane potential reaches threshold for an action potential.

Question 7

Which of the following is TRUE regarding saltatory conduction in myelinated axons?

Accepted Answer

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

Question 8

Which neurotransmitter is released at the neuromuscular junction to stimulate muscle contraction?

Accepted Answer

Acetylcholine

Question 9

A patient is exposed to a toxin that blocks voltage-gated Na$$^+$$ channels. What is the most likely effect on neuronal signaling?

Accepted Answer

Action potentials will fail to initiate and propagate.

Question 10

Which of the following best describes the 'All-or-None Principle' of action potentials?

Accepted Answer

If threshold is reached, an action potential is generated with a fixed amplitude; if not, no action potential occurs.

Question 11

Which of the following equations correctly represents Ohm's Law as applied to membrane potential?

Accepted Answer

$$I = V \div R$$

Question 12

Which type of neuron is most likely to transmit sensory information from the skin to the CNS?

Accepted Answer

Unipolar neuron

Question 13

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

Accepted Answer

They act as immune cells, removing debris and pathogens.

Question 14

Which of the following is a direct effect of opening K$$^+$$ channels on the postsynaptic membrane?

Accepted Answer

Hyperpolarization and inhibition of the postsynaptic neuron

Question 15

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

Accepted Answer

Graded potentials can summate and vary in amplitude, while action potentials are all-or-none and propagate without decrement.

Question 16

Which of the following neurotransmitters is classified as an amino acid and is primarily inhibitory in the CNS?

Accepted Answer

GABA

Question 17

A neuron has a resting membrane potential of $$-70\ 	ext{mV}. If $$the membrane potential changes to $$-55\ 	ext{mV}$$, what is most likely to occur?

Accepted Answer

An action potential will be triggered if $$-55\ 	ext{mV} is $$the threshold.

Question 18

Which of the following best describes the function of the axon hillock?

Accepted Answer

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

Question 19

Which of the following is TRUE regarding the absolute refractory period?

Accepted Answer

No action potential can be generated, regardless of stimulus strength.

Question 20

Which of the following best describes the effect of neurotransmitter binding to a postsynaptic receptor that activates a second messenger system?

Accepted Answer

It initiates a cascade of intracellular events that can modulate cell function over a longer time.

Fundamentals of the Nervous System and Nervous Tissue: Study Notes

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