Nerve and muscle: electrical synapse: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Nerve and muscle: electrical synapse

Sample item

Reflex escape circuits in some animals use synapses in which impulses pass between neurones with almost no delay and in both directions. Which structure forms these synapses?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Gap junctions of connexon channels

Electrical synapses are gap junctions in which connexin channels link cytoplasm of adjacent cells, allowing ionic current to flow directly and bidirectionally with negligible delay. Chemical synapses are unidirectional and add a delay of around half a millisecond.

Option by option

  • A. Gap junctions of connexon channels (correct)

    Correct. Gap junction channels couple cells electrically.

  • B. Axo-axonal GABAergic terminals

    Axo-axonal GABAergic terminals mediate presynaptic inhibition by chemical transmission.

  • C. Chemical synapses with synaptic vesicles

    Chemical synapses are one-way and have a synaptic delay.

  • D. Neuromuscular junctions with acetylcholine

    Neuromuscular junctions are chemical synapses using acetylcholine.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is A, Gap junctions of connexon channels. Electrical synapses are gap junctions in which connexin channels link cytoplasm of adjacent cells, allowing ionic current to flow directly and bidirectionally with negligible delay.

Why is "Axo-axonal GABAergic terminals" not the answer?

Axo-axonal GABAergic terminals mediate presynaptic inhibition by chemical transmission.

Why is "Chemical synapses with synaptic vesicles" not the answer?

Chemical synapses are one-way and have a synaptic delay.

Why is "Neuromuscular junctions with acetylcholine" not the answer?

Neuromuscular junctions are chemical synapses using acetylcholine.

What concept does this question test?

It tests Nerve and muscle: electrical synapse in Physiology. Chemical synapses are unidirectional and add a delay of around half a millisecond.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Nerve and muscle: electrical synapse?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.