Question 1

Which of the following best describes the function of oligodendrocytes in the central nervous system (CNS)?

Accepted Answer

They produce myelin sheaths that insulate axons in the CNS.

Question 2

A patient has a demyelinating disease affecting the CNS. Which of the following is most likely impaired as a result?

Accepted Answer

The ability of axons to transmit action potentials rapidly due to loss of saltatory conduction.

Question 3

Which equation would you use to calculate the equilibrium potential for potassium ($K^+$) ions across a neuronal membrane?

Accepted Answer

$E_{K^+} = \frac{RT}{zF} \ln \left( \frac{[K^+]_{out}}{[K^+]_{in}} \right)$

Question 4

During the rising phase of an action potential, which of the following events occurs first?

Accepted Answer

Voltage-gated $Na^+$ channels open, causing rapid $Na^+$ influx.

Question 5

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

Accepted Answer

Temporal summation

Question 6

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

Accepted Answer

The refractory period prevents the membrane behind the action potential from depolarizing again immediately.

Question 7

Which of the following neurotransmitters is most directly involved in stimulating skeletal muscle contraction at the neuromuscular junction?

Accepted Answer

Acetylcholine

Question 8

A neuron is at rest with a membrane potential of $-70\ \mathrm{mV}$. If the membrane suddenly becomes permeable only to $Na^+$, what will happen to the membrane potential?

Accepted Answer

It will move toward the equilibrium potential of $Na^+$ (depolarize).

Question 9

Which of the following is a function of astrocytes in the CNS?

Accepted Answer

Regulating extracellular ion concentrations and supporting the blood-brain barrier

Question 10

Which of the following best describes the 'all-or-none' principle of action potentials?

Accepted Answer

Once threshold is reached, an action potential of fixed size is generated regardless of stimulus strength.

Question 11

A patient is given a drug that blocks voltage-gated $K^+$ channels. What effect would this have on the action potential?

Accepted Answer

It would prolong repolarization, making the action potential last longer.

Question 12

Which of the following is true regarding chemical synapses?

Accepted Answer

They involve neurotransmitter release from the presynaptic terminal into the synaptic cleft.

Question 13

Which of the following best describes the role of the sodium-potassium pump ($Na^+/K^+$ ATPase) in neurons?

Accepted Answer

It maintains the resting membrane potential by actively transporting $3\ Na^+$ out and $2\ K^+$ in per ATP hydrolyzed.

Question 14

A neuron receives both excitatory and inhibitory inputs at the same time. Which of the following best describes the process that determines whether an action potential will be generated?

Accepted Answer

Spatial summation, where the effects of all inputs are combined at the axon hillock.

Question 15

Which of the following neurotransmitters is classified as an inhibitory amino acid in the CNS?

Accepted Answer

Glycine

Question 16

If the diameter of an axon increases, what is the expected effect on the speed of action potential propagation?

Accepted Answer

It will increase due to decreased resistance.

Question 17

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

Accepted Answer

Myelin allows action potentials to 'jump' between nodes of Ranvier via saltatory conduction.

Question 18

Which of the following is a characteristic of graded potentials but NOT action potentials?

Accepted Answer

They can be depolarizing or hyperpolarizing and vary in amplitude.

Question 19

A postsynaptic neuron receives input from several presynaptic neurons at different locations on its dendrites. What is this process called?

Accepted Answer

Spatial summation

Question 20

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.

Neural Signaling and Synaptic Transmission: Study Notes for Anatomy & Physiology

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