Question 1

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

Accepted Answer

The refractory period caused by inactivated Na channels prevents the action potential from traveling backward.

Question 2

A patient is exposed to a toxin that blocks voltage-gated K channels in neurons. Which of the following would most likely occur as a result?

Accepted Answer

The neuron would be unable to repolarize efficiently, prolonging the action potential.

Question 3

Which equation is used to calculate the equilibrium potential for a particular ion across a neuron's membrane?

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{outside}}{[ion]_{inside}} \right)$$

Question 4

Which of the following best describes the role of the sodium-potassium pump in maintaining the resting membrane potential?

Accepted Answer

It uses ATP to transport K into the cell and Na out of the cell, maintaining their concentration gradients.

Question 5

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

Accepted Answer

Temporal summation; the EPSPs add together, increasing the likelihood of reaching threshold.

Question 6

Which of the following statements about myelinated axons is correct?

Accepted Answer

Voltage-gated sodium channels are concentrated at the nodes of Ranvier, allowing saltatory conduction.

Question 7

Which neurotransmitter is most directly involved in muscle stimulation, memory formation, and learning in vertebrates?

Accepted Answer

Acetylcholine

Question 8

A scientist discovers a new neurotransmitter that is synthesized on demand and not stored in vesicles. It is rapidly broken down after production. To which class of neurotransmitters does this molecule most likely belong?

Accepted Answer

Gases

Question 9

Which of the following best explains why a single EPSP is usually insufficient to trigger an action potential in a postsynaptic neuron?

Accepted Answer

The magnitude of a single EPSP is typically too small to reach the threshold at the axon hillock.

Question 10

Which of the following is a correct pairing of a neurotransmitter and its primary effect in the central nervous system?

Accepted Answer

GABA – major inhibitory neurotransmitter in the brain

Question 11

A drug that blocks ligand-gated ion channels at the postsynaptic membrane would most directly interfere with which process?

Accepted Answer

Generation of postsynaptic potentials

Question 12

Which of the following best describes the difference between ionotropic and metabotropic receptors at chemical synapses?

Accepted Answer

Ionotropic receptors directly open ion channels, while metabotropic receptors activate signal transduction pathways involving second messengers.

Question 13

Which of the following scenarios would most likely result in hyperpolarization of a neuron?

Accepted Answer

Opening of gated K channels, allowing K to diffuse out

Question 14

Which of the following is true regarding the summation of postsynaptic potentials?

Accepted Answer

Both spatial and temporal summation can combine to trigger an action potential if threshold is reached.

Question 15

Which of the following best explains why the resting membrane potential is typically negative in neurons?

Accepted Answer

There are more open K channels than Na channels at rest, allowing K to diffuse out and leaving behind a net negative charge.

Question 16

Which of the following is a correct statement about the role of glial cells in the nervous system?

Accepted Answer

Glial cells provide structural and metabolic support to neurons.

Question 17

A patient is given a drug that mimics the action of endorphins. Which of the following effects would most likely be observed?

Accepted Answer

Decreased perception of pain

Question 18

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

Accepted Answer

It hyperpolarizes the postsynaptic membrane, moving it farther from threshold.

Question 19

Which of the following neurotransmitters is synthesized from tyrosine and is involved in the 'fight or flight' response?

Accepted Answer

Norepinephrine

Question 20

Which of the following is a unique feature of nitric oxide (NO) as a neurotransmitter compared to other classes?

Accepted Answer

It is synthesized on demand and diffuses rapidly across membranes.

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

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