Q: In the establishment of the resting membrane potential in a neuron, which ion channels are primarily open?

Leak K\textsuperscript{+} channels

Q: A nerve cell at rest uses considerably more energy than a muscle cell. Why?

Nerve cells have a higher rate of Na\textsuperscript{+}/K\textsuperscript{+} ATPase activity to maintain ion gradients

Q: Which of the following best explains why the resting membrane potential is closer to the equilibrium potential of K\textsuperscript{+} than Na\textsuperscript{+}?

The membrane is more permeable to K\textsuperscript{+} than Na\textsuperscript{+} at rest

Q: During the rising phase of the action potential, what ion moves into the neuron and what channels are responsible?

Na\textsuperscript{+} enters via voltage-gated Na\textsuperscript{+} channels

Question 1

In the establishment of the resting membrane potential in a neuron, which ion channels are primarily open?

Accepted Answer

Leak K	extsuperscript{+} channels

Question 2

A nerve cell at rest uses considerably more energy than a muscle cell. Why?

Accepted Answer

Nerve cells have a higher rate of Na	extsuperscript{+}/K	extsuperscript{+} ATPase activity to maintain ion gradients

Question 3

What is the equilibrium potential for K	extsuperscript{+} ($$E_K) in a $$typical neuron, given intracellular [K	extsuperscript{+}] = 140 mM and extracellular [K	extsuperscript{+}] = 5 mM? Use the Nernst equation: $$E_K = \frac{RT}{zF} \ln \left( \frac{[K^+]_{out}}{[K^+]_{in}} ight)$$

Accepted Answer

Approximately $$-90 mV$$

Question 4

Which of the following best describes the role of the myelin sheath in nerve conduction?

Accepted Answer

It insulates the axon, enabling saltatory conduction and increasing conduction velocity

Question 5

What is the function of the node of Ranvier in a myelinated axon?

Accepted Answer

It is the location of voltage-gated ion channels that regenerate the action potential

Question 6

If voltage-gated Na	extsuperscript{+} channels were blocked by a drug, what would happen to the action potential in a neuron?

Accepted Answer

The action potential would not be initiated

Question 7

Which of the following best explains why the resting membrane potential is closer to the equilibrium potential of K	extsuperscript{+} than Na	extsuperscript{+}?

Accepted Answer

The membrane is more permeable to K	extsuperscript{+} than Na	extsuperscript{+} at rest

Question 8

During the rising phase of the action potential, what ion moves into the neuron and what channels are responsible?

Accepted Answer

Na	extsuperscript{+} enters via voltage-gated Na	extsuperscript{+} channels

Question 9

What is the absolute refractory period and why does it occur?

Accepted Answer

It is when the neuron cannot fire another action potential because voltage-gated Na	extsuperscript{+} channels are inactivated

Question 10

Which of the following would most likely occur in a patient with Multiple Sclerosis (MS), a disease that destroys myelin?

Accepted Answer

Saltatory conduction would be impaired, leading to slower nerve conduction

Question 11

What is a synapse?

Accepted Answer

A junction between a neuron and another cell where communication occurs

Question 12

Which of the following best describes an excitatory postsynaptic potential (EPSP)?

Accepted Answer

A depolarization that brings the postsynaptic membrane closer to threshold

Question 13

How do neurotransmitters influence the postsynaptic cell?

Accepted Answer

By opening or closing ion channels, altering membrane potential

Question 14

Which of the following is NOT a function of a G-protein linked receptor?

Accepted Answer

Directly opening ion channels

Question 15

If a drug blocked all voltage-gated K	extsuperscript{+} channels in a neuron, what would happen to the action potential?

Accepted Answer

Repolarization would be delayed, prolonging the action potential

Question 16

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

Accepted Answer

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

Question 17

Which of the following would NOT stimulate an action potential in a neuron?

Accepted Answer

Opening ligand-gated K	extsuperscript{+} channels

Question 18

What is the main difference between a presynaptic and a postsynaptic cell at a synapse?

Accepted Answer

The presynaptic cell releases neurotransmitters, the postsynaptic cell receives them

Question 19

Which of the following best describes electrochemical equilibrium for K	extsuperscript{+}?

Accepted Answer

The point at which the electrical and chemical gradients for K	extsuperscript{+} are equal and opposite, resulting in no net movement of K	extsuperscript{+}

Question 20

A patient is given a drug that blocks all synaptic vesicle release. What is the most immediate effect on neural communication?

Accepted Answer

Neurotransmitter release will be inhibited, preventing synaptic transmission

Neurophysiology: Resting Membrane Potential, Action Potentials, and Synaptic Transmission

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