Nerve physiology: 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.

Try it

Physiology · Nerve physiology

Sample item

Which event causes the rapid depolarization phase of a neuronal action potential?

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

The answer and the reasoning

B. Opening of voltage-gated sodium channels

Rapid opening of voltage-gated sodium channels causes inward sodium current and the steep depolarizing upstroke of the neuronal action potential.

Option by option

  • A. Opening of potassium leak channels

    Potassium channels mainly support repolarization.

  • B. Opening of voltage-gated sodium channels (correct)

    Correct: sodium influx produces rapid membrane depolarization.

  • C. Activation of sodium-potassium pump only

    The pump maintains gradients but does not cause the rapid upstroke.

  • D. Closure of all ion channels

    Action potentials require changing channel conductance.

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.

More Physiology questions

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is B, Opening of voltage-gated sodium channels. Rapid opening of voltage-gated sodium channels causes inward sodium current and the steep depolarizing upstroke of the neuronal action potential.

Why is "Opening of potassium leak channels" not the answer?

Potassium channels mainly support repolarization.

Why is "Activation of sodium-potassium pump only" not the answer?

The pump maintains gradients but does not cause the rapid upstroke.

Why is "Closure of all ion channels" not the answer?

Action potentials require changing channel conductance.

What concept does this question test?

It tests Nerve physiology in Physiology. The correct option holds because: Correct: sodium influx produces rapid membrane depolarization.

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 physiology?

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.