Question 1

Which of the following best describes the sequence of events at a chemical synapse following the arrival of an action potential at the axon terminal?

Accepted Answer

Action potential depolarizes the axon terminal, voltage-gated Ca$$^{2+}$$ channels open, Ca$$^{2+}$$ influx triggers exocytosis of neurotransmitter, neurotransmitter diffuses across the synaptic cleft, neurotransmitter binds to post-synaptic receptors.

Question 2

A strong stimulus applied to a neuron results in which of the following changes at the synapse?

Accepted Answer

Increased frequency of action potentials, leading to more Ca$$^{2+}$$ influx and greater neurotransmitter release.

Question 3

Which synapse location is primarily responsible for modulating neurotransmitter release rather than the likelihood of action potential generation?

Accepted Answer

Axoaxonic synapse

Question 4

Which of the following mechanisms is NOT a way to terminate neurotransmitter activity in the synaptic cleft?

Accepted Answer

Binding to voltage-gated Ca$$^{2+}$$ channels

Question 5

Acetylcholine (ACh) binds to two types of cholinergic receptors. Which statement correctly matches the receptor type with its mechanism and speed of response?

Accepted Answer

Nicotinic receptors are receptor-channels and produce fast responses; muscarinic receptors are GPCRs and produce slow responses.

Question 6

A patient is exposed to curare, a toxin that acts as a nicotinic receptor antagonist. What is the expected effect on neural signalling?

Accepted Answer

Decreased ACh signalling due to blocked receptor activation.

Question 7

Which of the following best describes the effect of opening Na$$^+$$ channels on the post-synaptic membrane?

Accepted Answer

More Na$$^+$$ moves into the cell, causing depolarization and an excitatory post-synaptic potential (EPSP).

Question 8

Which neurotransmitter is broken down in the synaptic cleft by acetylcholinesterase, and what are the products of this reaction?

Accepted Answer

Acetylcholine; products are choline and acetate.

Question 9

A neuron receives two EPSPs of +8 mV and one IPSP of -2 mV at the trigger zone. If the threshold for action potential generation is +10 mV, will an action potential be generated?

Accepted Answer

No, because the net potential is +6 mV, which is below threshold.

Question 10

Which of the following drugs would increase acetylcholine signalling by inhibiting acetylcholinesterase?

Accepted Answer

Galantamine

Question 11

In a scenario where several subthreshold EPSPs occur rapidly at the same synapse, what process allows these to sum and potentially reach threshold for an action potential?

Accepted Answer

Temporal summation

Question 12

Which of the following is an example of a divergent neural pathway?

Accepted Answer

A single presynaptic neuron sending signals to multiple post-synaptic neurons during a withdrawal reflex.

Question 13

What is the effect of opening Cl$$^-$$ channels on the post-synaptic membrane?

Accepted Answer

Cl$$^-$$ moves into the cell, causing hyperpolarization and an IPSP.

Question 14

Which of the following best describes global presynaptic inhibition?

Accepted Answer

All axon collaterals are inhibited, preventing neurotransmitter release from all terminals.

Question 15

Which of the following molecules is NOT classified as a neurotransmitter?

Accepted Answer

Acetyl-CoA

Question 16

A neuron receives two EPSPs of +2 mV each and four IPSPs of -1 mV each in rapid succession. What is the net graded potential at the trigger zone?

Accepted Answer

$$+2\,	ext{mV} + +2\,	ext{mV} + (-1\,	ext{mV} 	imes 4) = +4\,	ext{mV} - 4\,	ext{mV} = 0\,	ext{mV}$$

Question 17

Which of the following would result in an inhibitory post-synaptic potential (IPSP)?

Accepted Answer

Opening K$$^+ or Cl$^-$$ channels

Question 18

Which of the following statements about muscarinic receptors is correct?

Accepted Answer

They are G-protein coupled receptors (GPCRs) that produce slow, longer-term effects.

Question 19

If a drug causes acetylcholine to remain in the synaptic cleft longer, what is the most likely effect on post-synaptic signalling?

Accepted Answer

Increased post-synaptic signalling due to prolonged receptor activation.

Neural Physiology: Chemical Synapses, Neurotransmitters, and Post-Synaptic Responses

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