Question 1

Which of the following best describes the resting membrane potential of a typical neuron?

Accepted Answer

The inside of the cell is negative relative to the outside, typically -70 mV.

Question 2

What is the primary function of the sodium-potassium pump ($$\mathrm{Na^+/K^+}$$ ATPase) in maintaining the resting membrane potential?

Accepted Answer

It pumps $$3\mathrm{Na^+}$$ out and $$2\mathrm{K^+} in $$per ATP, maintaining ion gradients.

Question 3

Which type of ion channel is always open and allows ions to move down their concentration gradient?

Accepted Answer

Leak channels

Question 4

A neuron receives several excitatory postsynaptic potentials (EPSPs) in rapid succession at the same synapse. What is this process called?

Accepted Answer

Temporal summation

Question 5

During the depolarization phase of an action potential, which ion moves and in which direction?

Accepted Answer

$$\mathrm{Na^+}$$ enters the cell

Question 6

Which equation best represents Ohm’s Law as applied to neurons?

Accepted Answer

$$V = I 	imes R$$

Question 7

What is the effect of opening ligand-gated chloride ($$\mathrm{Cl^-}) $$channels on the postsynaptic membrane?

Accepted Answer

Hyperpolarization, making the membrane potential more negative

Question 8

Which of the following best explains why the axon hillock is the site of action potential initiation?

Accepted Answer

It contains the highest density of voltage-gated $$\mathrm{Na^+}$$ channels.

Question 9

A patient has a mutation that increases the number of $$\mathrm{K^+}$$ leak channels in their neurons. What is the most likely effect on their resting membrane potential?

Accepted Answer

The resting membrane potential becomes more negative.

Question 10

Which of the following is true about the absolute refractory period?

Accepted Answer

No action potential can be generated regardless of stimulus strength.

Question 11

Saltatory conduction is faster than continuous conduction because:

Accepted Answer

Action potentials jump from node to node, reducing the number of depolarizations required.

Question 12

Which neurotransmitter is most commonly associated with inhibitory synapses in the brain and is known to reduce anxiety?

Accepted Answer

Gamma-aminobutyric acid (GABA)

Question 13

If a neuron’s membrane potential changes from $$-70\ \mathrm{mV} to$$ $$-55\ \mathrm{mV}$$, what has occurred?

Accepted Answer

Depolarization

Question 14

Which process is responsible for removing neurotransmitters from the synaptic cleft by breaking them down into inactive components?

Accepted Answer

Enzymatic degradation

Question 15

A neuron receives both EPSPs and IPSPs at the same time. What determines whether an action potential will be generated?

Accepted Answer

The sum of all local potentials at the axon hillock reaching threshold

Question 16

Which of the following best describes the role of neuromodulators?

Accepted Answer

They alter the response of neurons to neurotransmitters, increasing or decreasing synaptic transmission.

Question 17

Which of the following would most likely result from a drug that blocks voltage-gated $$\mathrm{Na^+}$$ channels?

Accepted Answer

Inhibition of action potential generation

Question 18

Which class of neurotransmitter is released at cholinergic synapses and can be either excitatory or inhibitory depending on the target tissue?

Accepted Answer

Acetylcholine (ACh)

Question 19

A neuron is exposed to a toxin that prevents the reuptake of neurotransmitters. What is the most likely effect?

Accepted Answer

Neurotransmitter levels in the synaptic cleft will remain elevated, prolonging synaptic transmission.

Question 20

Which of the following is a direct effect of opening voltage-gated $$\mathrm{K^+}$$ channels during an action potential?

Accepted Answer

Repolarization of the membrane

Membrane Potentials and Electrophysiology of Neurons

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