Question 1

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

Accepted Answer

Inactivated $$\mathrm{Na^+}$$ channels behind the zone of depolarization prevent backward propagation.

Question 2

A patient is exposed to botulinum toxin, which blocks acetylcholine release at neuromuscular junctions. What is the most likely physiological effect?

Accepted Answer

Paralysis due to failure of muscle stimulation.

Question 3

Which process is responsible for the rapid transmission of action potentials in myelinated axons?

Accepted Answer

Saltatory conduction, where action potentials jump between nodes of Ranvier.

Question 4

What is the primary function of voltage-gated calcium channels at the presynaptic terminal?

Accepted Answer

To trigger fusion of synaptic vesicles and release of neurotransmitter.

Question 5

Which of the following best describes temporal summation?

Accepted Answer

EPSPs produced in rapid succession at the same synapse add together.

Question 6

A neuron receives simultaneous excitatory inputs at multiple dendrites. What is this phenomenon called, and what is its effect?

Accepted Answer

Spatial summation; can depolarize the membrane to threshold and trigger an action potential.

Question 7

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

Accepted Answer

Acetylcholine

Question 8

What is the effect of opening ligand-gated ion channels by neurotransmitters on the postsynaptic membrane?

Accepted Answer

It generates a postsynaptic potential by changing the membrane potential.

Question 9

Which of the following is TRUE regarding the refractory period of a neuron?

Accepted Answer

It is caused by temporary inactivation of $$\mathrm{Na^+}$$ channels.

Question 10

Which neurotransmitter is classified as a biogenic amine and is associated with mood, attention, and learning?

Accepted Answer

Serotonin

Question 11

A patient with Parkinson’s disease is most likely to have a deficiency in which neurotransmitter in the brain?

Accepted Answer

Dopamine

Question 12

Which of the following is NOT a mechanism for terminating neurotransmitter action in the synaptic cleft?

Accepted Answer

Activation of voltage-gated sodium channels

Question 13

Which of the following statements about neurotransmitters is CORRECT?

Accepted Answer

Neurotransmitters can have different effects depending on the type of receptor present.

Question 14

Which equation best represents the change in membrane potential ($$V_m) $$due to the opening of ligand-gated ion channels?

Accepted Answer

$$V_m = V_{rest} + \Delta V_{EPSP}$$

Question 15

Which of the following is a direct consequence of the myelin sheath on axonal conduction?

Accepted Answer

It increases the speed of action potential propagation by enabling saltatory conduction.

Question 16

Which neurotransmitter is an amino acid and is primarily inhibitory in the central nervous system?

Accepted Answer

GABA (gamma-aminobutyric acid)

Question 17

A neuron receives both excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) at the same time. What determines whether an action potential will be generated?

Accepted Answer

The net effect of spatial and temporal summation reaching the threshold potential.

Question 18

Which of the following is a plausible effect of a drug that blocks the reuptake of serotonin in the synaptic cleft?

Accepted Answer

Increased serotonin signaling, which may alleviate symptoms of depression.

Question 19

Which region of the brain is primarily responsible for decision making and planning?

Accepted Answer

Prefrontal cortex

Question 20

Which of the following best describes the role of the axon hillock in neuronal signaling?

Accepted Answer

It is the site where action potentials are typically initiated due to summation of postsynaptic potentials.

Neuronal Signaling and Neurotransmission: Structure and Function in the Nervous System

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