Question 1

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

Accepted Answer

It pumps 3 Na+ ions out of the cell for every 2 K+ ions in, resulting in a net negative charge inside.

Question 2

If the equilibrium potential for K+ is $$-90\ \mathrm{mV}$$ and the resting membrane potential is $$-70\ \mathrm{mV}$$, what does this indicate about the movement of K+ ions at rest?

Accepted Answer

K+ ions tend to move out of the cell, but the electrical gradient partially opposes this movement.

Question 3

Which of the following events would most likely result in a graded depolarization (EPSP) at the postsynaptic membrane?

Accepted Answer

Opening of chemically-regulated Na+ channels

Question 4

A neuron receives two simultaneous stimuli at different locations on its dendrites, resulting in a combined effect that reaches threshold. This is an example of:

Accepted Answer

Spatial summation

Question 5

During the absolute refractory period, which of the following is true?

Accepted Answer

Voltage-gated Na+ channels are inactivated and cannot reopen.

Question 6

Which of the following best explains why myelinated axons conduct action potentials faster than unmyelinated axons?

Accepted Answer

Action potentials jump from node to node in a process called saltatory conduction.

Question 7

A patient is exposed to a drug that blocks acetylcholinesterase (AChE) at the synaptic cleft. What is the most likely effect on synaptic transmission?

Accepted Answer

ACh will accumulate, causing prolonged depolarization of the postsynaptic membrane.

Question 8

Which of the following best describes the effect of an inhibitory postsynaptic potential (IPSP)?

Accepted Answer

It hyperpolarizes the postsynaptic membrane, making an action potential less likely.

Question 9

Which of the following is the correct sequence of events during an action potential?

Accepted Answer

Depolarization, repolarization, hyperpolarization, return to resting potential

Question 10

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

Accepted Answer

The neuron has depolarized and reached threshold.

Question 11

Which of the following neural circuit types is best suited for amplifying a signal to multiple effectors, such as in a motor pathway?

Accepted Answer

Diverging circuit

Question 12

A neuron is exposed to a chemical that opens chemically-regulated K+ channels. What is the most likely effect on the membrane potential?

Accepted Answer

Hyperpolarization due to efflux of K+

Question 13

Which of the following best explains why the equilibrium potential for Na+ is positive ($$+66\ \mathrm{mV}) $$while the resting membrane potential is negative ($$-70\ \mathrm{mV}$$)?

Accepted Answer

The Na+/K+ pump moves more Na+ out than K+ in, and the membrane is more permeable to K+ at rest.

Question 14

During which phase of the action potential are voltage-gated Na+ channels inactivated and voltage-gated K+ channels open?

Accepted Answer

Repolarization

Question 15

Which of the following would most likely increase the speed of action potential propagation along an axon?

Accepted Answer

Increasing the thickness of the myelin sheath

Question 16

A neuron receives a rapid series of excitatory postsynaptic potentials (EPSPs) from a single presynaptic neuron. This is an example of:

Accepted Answer

Temporal summation

Question 17

Which of the following best describes the effect of facilitation in neural integration?

Accepted Answer

A shift in transmembrane potential closer to threshold due to summation of EPSPs

Question 18

Which of the following is a characteristic of a reverberating neural circuit?

Accepted Answer

It provides feedback stimulation to presynaptic neurons, maintaining activity.

Question 19

Which of the following best explains why an action potential is considered 'all-or-none'?

Accepted Answer

Once threshold is reached, the action potential always reaches the same peak value.

Membrane Potentials, Action Potentials, and Synaptic Transmission in Neurons

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