Question 1

Which type of ion channel opens in response to the binding of a neurotransmitter to its receptor on the channel?

Accepted Answer

Ligand-gated ion channel

Question 2

The resting membrane potential of a neuron is primarily established by which of the following mechanisms?

Accepted Answer

The Na$$^{+}/K$^{+}$$ ATPase pump and K$$^{+}$$ leak channels

Question 3

If the extracellular concentration of K$$^{+}$$ increases significantly, what effect would this have on the resting membrane potential ($$V_m) of a $$neuron?

Accepted Answer

$$V_m$$ would become less negative (depolarize)

Question 4

Which equation is used to calculate the equilibrium potential for a specific ion across a membrane?

Accepted Answer

Nernst equation: $$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 5

During the depolarization phase of an action potential, which ion channels open and what is the direction of ion movement?

Accepted Answer

Voltage-gated Na$$^{+}$$ channels open; Na$$^{+}$$ moves into the cell

Question 6

Which of the following best describes the 'all-or-nothing' principle of action potentials?

Accepted Answer

Once threshold is reached, an action potential will always fire with the same amplitude

Question 7

A patient presents with a mutation that impairs voltage-gated Na$$^{+}$$ channels. Which phase of the action potential would be most affected?

Accepted Answer

Depolarization

Question 8

Which type of conduction allows action potentials to 'jump' from one node of Ranvier to the next, increasing the speed of transmission?

Accepted Answer

Saltatory conduction

Question 9

During the absolute refractory period, why is it impossible to initiate another action potential?

Accepted Answer

Voltage-gated Na$$^{+}$$ channels are inactivated

Question 10

Which of the following best explains why graded potentials can be either depolarizing or hyperpolarizing?

Accepted Answer

They result from the opening of ligand-gated or mechanically gated channels, allowing different ions to flow

Question 11

A neuron receives simultaneous excitatory and inhibitory inputs. Which of the following determines whether an action potential will be generated?

Accepted Answer

The spatial and temporal summation of graded potentials at the axon hillock

Question 12

Which of the following is TRUE regarding the propagation of action potentials in myelinated axons?

Accepted Answer

Action potentials travel faster due to saltatory conduction

Question 13

Which ion is most responsible for the repolarization phase of the action potential?

Accepted Answer

K$$^{+}$$ efflux

Question 14

A neuron is exposed to a toxin that blocks K$$^{+}$$ leak channels. What is the most likely effect on the resting membrane potential?

Accepted Answer

The resting membrane potential would become less negative

Question 15

Which of the following best describes the role of the Na$$^{+}/K$^{+}$$ ATPase in neurons?

Accepted Answer

It actively transports 3 Na$$^{+}$$ out and 2 K$$^{+} in$$, maintaining the electrochemical gradients

Question 16

Which of the following scenarios would most likely result in hyperpolarization of a neuron?

Accepted Answer

Opening of ligand-gated Cl$$^{-}$$ channels

Question 17

Which of the following is a key difference between graded potentials and action potentials?

Accepted Answer

Graded potentials can summate, while action potentials cannot

Question 18

A neuron is stimulated at multiple points along its dendrites. Which property of graded potentials allows these stimuli to combine and potentially trigger an action potential?

Accepted Answer

Spatial summation

Question 19

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

Accepted Answer

The absolute refractory period prevents backward propagation

Electrophysiology of Neurons: Ion Channels, Electrochemical Gradients, and Membrane Potentials

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