Question 1

Which of the following best describes the role of the Na⁺/K⁺ ATPase pump in maintaining the resting membrane potential of a neuron?

Accepted Answer

It actively transports 3 Na⁺ ions out of the cell and 2 K⁺ ions into the cell, using ATP.

Question 2

A neuron’s membrane potential is measured at -70 mV. If the membrane suddenly becomes permeable only to K⁺, what will the membrane potential approach?

Accepted Answer

The equilibrium potential for K⁺ ($$E_{K})$$

Question 3

Which equation correctly describes the relationship between membrane current (I), voltage (V), and resistance (R) in a neuron?

Accepted Answer

$$I = V / R$$

Question 4

If a neuron’s membrane resistance ($$R_m) $$decreases while membrane capacitance ($$C_m) $$remains constant, what happens to the membrane time constant ($$	au_m$$)?

Accepted Answer

$$	au_m$$ decreases

Question 5

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

Accepted Answer

Oligodendrocytes

Question 6

A patient presents with hyperkalemia (elevated extracellular K⁺). What effect does this have on the neuron’s resting membrane potential?

Accepted Answer

It depolarizes the neuron, making it more excitable.

Question 7

Which of the following best explains why neurons require a constant supply of metabolic energy?

Accepted Answer

To power the Na⁺/K⁺ ATPase pump that maintains ion gradients.

Question 8

Given the Nernst equation for an ion $$i$$: $$E_i = \frac{RT}{nF} \ln \frac{[i]_{extracell.}}{[i]_{intracell.}}$$, what would happen to $$E_K if $$extracellular K⁺ concentration increases?

Accepted Answer

$$E_K$$ becomes less negative

Question 9

Which of the following is a function of astrocytes in the central nervous system?

Accepted Answer

Regulating K⁺ and neurotransmitter concentrations in the extracellular space

Question 10

A neuron’s membrane is permeable to Na⁺, K⁺, and Cl⁻. Which equation best predicts the resting membrane potential ($$V_m$$)?

Accepted Answer

$$V_m = \frac{g$$_{Na}$$E_{Na} + g$$_{K}$$E_{K} + g$$_{Cl}$$E_{Cl}}{g_{Na} + g_{K} + g_{Cl}}$$

Question 11

Which of the following would most likely occur if the Na⁺/K⁺ ATPase pump stopped functioning in a neuron?

Accepted Answer

The neuron would lose its resting membrane potential and become unable to signal.

Question 12

Which of the following best describes the effect of increasing membrane capacitance ($$C_m) on $$the speed of voltage changes across the neuronal membrane?

Accepted Answer

Decreases the speed of voltage changes

Question 13

Which of the following is a correct statement about the direction of current flow during depolarization in a neuron?

Accepted Answer

Positive charges (cations) flow into the cell or negative charges (anions) flow out of the cell.

Question 14

Which of the following scenarios would most likely result in neuronal hyperexcitability?

Accepted Answer

Increased extracellular K⁺ concentration (hyperkalemia)

Question 15

Which of the following best explains why the resting membrane potential is closer to $$E_K$$ than to $$E_{Na} in $$most neurons?

Accepted Answer

The membrane is more permeable to K⁺ than to Na⁺ at rest.

Question 16

Which of the following is a real-life consequence of a failure in the blood-brain barrier?

Accepted Answer

Unregulated ionic concentrations in the brain, leading to neuronal dysfunction

Question 17

A neuron is modeled as a circuit with a resistor ($$R_m) $$and capacitor ($$C_m) in $$parallel. If a current pulse is applied, which equation describes the change in membrane potential over time?

Accepted Answer

$$V_m = I_m R_m (1 - e$$^{-t / (R_m C_m)}$$)$$

Question 18

Which of the following best describes the effect of myelination on the speed of action potential propagation?

Accepted Answer

Myelination decreases membrane capacitance and increases conduction speed.

Question 19

Which of the following is a function of microglia in the central nervous system?

Accepted Answer

Acting as scavengers and immune cells

The Neuron: Structure, Function, and Membrane Properties

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