Question 1

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

Accepted Answer

Voltage-gated Na+ channels become inactivated immediately after opening, creating a refractory period.

Question 2

A patient is exposed to tetrodotoxin (TTX) from puffer fish. What is the most immediate effect on their neurons?

Accepted Answer

Voltage-gated Na+ channels will be blocked, preventing action potential initiation.

Question 3

Which equation correctly describes the equilibrium potential for potassium ($$E_K) $$given the following concentrations: $$[K^+]_{out} = 5\ \mathrm{mM}$$, $$[K^+]_{in} = 140\ \mathrm{mM}$$?

Accepted Answer

$$E_K = 62\ \mathrm{mV} \left( \log \frac{5}{140} \right) = -90\ \mathrm{mV}$$

Question 4

Which of the following is a direct result of the sodium-potassium pump activity in neurons?

Accepted Answer

It maintains the resting membrane potential by pumping 3 Na+ out and 2 K+ in, using ATP.

Question 5

During the repolarization phase of an action potential, which event occurs?

Accepted Answer

Voltage-gated K+ channels open, allowing K+ to exit the cell.

Question 6

What is the primary function of myelin sheaths in vertebrate neurons?

Accepted Answer

To insulate axons and speed up action potential conduction via saltatory conduction.

Question 7

Which of the following best describes saltatory conduction?

Accepted Answer

Action potentials jump from one node of Ranvier to the next, increasing conduction speed.

Question 8

Which neurotransmitter is released at the neuromuscular junction and was first identified in Loewi’s experiment?

Accepted Answer

Acetylcholine

Question 9

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

Accepted Answer

Temporal summation

Question 10

Which of the following drugs would increase the amount of serotonin in the synaptic cleft by blocking its reuptake?

Accepted Answer

Selective serotonin reuptake inhibitor (SSRI)

Question 11

Which type of glial cell forms the myelin sheath in the central nervous system (CNS)?

Accepted Answer

Oligodendrocyte

Question 12

Which of the following best describes the role of the refractory period in action potential propagation?

Accepted Answer

It prevents the neuron from firing another action potential immediately, ensuring unidirectional propagation.

Question 13

Which of the following is a correct statement about the function of astrocytes in the CNS?

Accepted Answer

They induce the formation of the blood-brain barrier by causing tight junctions in capillary endothelial cells.

Question 14

Which of the following is a feature of metabotropic neurotransmitter receptors?

Accepted Answer

They activate second messenger pathways, resulting in slower but longer-lasting effects.

Question 15

Which of the following best explains why the resting membrane potential of a neuron is closer to $$E_K$$ than $$E_{Na}$$?

Accepted Answer

The membrane is more permeable to K+ than to Na+ at rest.

Question 16

Which of the following is a direct effect of opening ligand-gated Cl- channels on the postsynaptic membrane?

Accepted Answer

Generation of an inhibitory postsynaptic potential (IPSP)

Question 17

Which of the following best describes the function of the nodes of Ranvier?

Accepted Answer

They are gaps in the myelin sheath where voltage-gated Na+ channels are concentrated, allowing action potentials to regenerate.

Question 18

Which of the following is a consequence of demyelination in diseases such as multiple sclerosis?

Accepted Answer

Slowed or blocked action potential conduction due to loss of saltatory conduction

Question 19

Which of the following best describes the effect of a single EPSP on a postsynaptic neuron?

Accepted Answer

It depolarizes the membrane but is usually insufficient alone to reach threshold.

Question 20

Which of the following is a correct sequence of events during chemical synaptic transmission?

Accepted Answer

Action potential arrives at terminal → Ca2+ influx → vesicle fusion → neurotransmitter release

L7_8 Neurons, Synapses, and Signaling: Structure and Function of the Nervous System

Study Guide - Practice Questions

Study Guide - Flashcards