Question 1

Which of the following best describes the main finding of Otto Loewi's 1921 experiment with frog hearts?

Accepted Answer

It showed that neurotransmitters are responsible for communication between neurons.

Question 2

Which structure is primarily responsible for coupling two cells at an electrical synapse?

Accepted Answer

Gap junctions

Question 3

A patient is exposed to a toxin that blocks acetylcholinesterase (AchE). What is the most likely physiological effect?

Accepted Answer

Prolonged stimulation of postsynaptic acetylcholine receptors

Question 4

Which of the following neurotransmitters is primarily inhibitory in the central nervous system and is associated with motor control?

Accepted Answer

GABA (gamma-aminobutyric acid)

Question 5

Which of the following best explains why cardiac muscle cells can contract as a unit?

Accepted Answer

They are joined by gap junctions allowing electrical impulses to pass directly between cells.

Question 6

A neuron receives multiple excitatory postsynaptic potentials (EPSPs) from different presynaptic neurons at the same time. What is this process called?

Accepted Answer

Spatial summation

Question 7

Which of the following is TRUE regarding ligand-gated ion channels at the neuromuscular junction?

Accepted Answer

They allow both Na$$^+$$ and K$$^+$$ ions to pass when activated.

Question 8

Which of the following best describes the mechanism of action for muscarinic acetylcholine receptors?

Accepted Answer

They are G-protein-coupled receptors that indirectly affect ion channels.

Question 9

A drug that blocks monoamine oxidase (MAO) would most likely have which effect on neurotransmitter levels?

Accepted Answer

Increase the concentration of monoamines in the synaptic cleft

Question 10

Which of the following best explains why glycine and GABA are considered inhibitory neurotransmitters?

Accepted Answer

They hyperpolarize the postsynaptic membrane, making action potentials less likely.

Question 11

Which of the following equations best represents the hydrolysis of acetylcholine by acetylcholinesterase?

Accepted Answer

$$\mathrm{Acetylcholine} + \mathrm{H}_2\mathrm{O} \xrightarrow{\mathrm{AchE}} \mathrm{Acetate} + \mathrm{Choline}$$

Question 12

A patient with Huntington’s disease is found to have a deficiency in which neurotransmitter?

Accepted Answer

GABA (gamma-aminobutyric acid)

Question 13

Which of the following best describes the role of cAMP in monoamine neurotransmitter signaling?

Accepted Answer

It acts as a second messenger to activate protein kinases.

Question 14

Which of the following is a correct sequence of events at a chemical synapse leading to neurotransmitter release?

Accepted Answer

Action potential arrives, Ca$$^{2+}$$ channels open, Ca$$^{2+}$$ binds synaptotagmin, vesicles fuse, neurotransmitter released

Question 15

Which of the following best explains why EPSPs and IPSPs are graded potentials rather than action potentials?

Accepted Answer

Their amplitude depends on the amount of neurotransmitter released.

Question 16

Which of the following neurotransmitters is derived from tryptophan?

Accepted Answer

Serotonin

Question 17

A neuron receives rapid, repeated excitatory input from a single presynaptic neuron. What is this process called?

Accepted Answer

Temporal summation

Question 18

Which of the following is a characteristic of nicotinic acetylcholine receptors?

Accepted Answer

They are ligand-gated ion channels found at neuromuscular junctions.

Question 19

Which of the following best describes the effect of GABA binding to its receptor on the postsynaptic membrane?

Accepted Answer

It opens Cl$$^-$$ channels, causing hyperpolarization.

Question 20

Which of the following best explains the difference between electrical and chemical synapses?

Accepted Answer

Electrical synapses transmit signals via direct ionic current through gap junctions, while chemical synapses use neurotransmitter release.

Physio: Synapses and Neuromuscular Junctions

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