Ear and audiology: mechanotransduction in hair cells: practice question

A ENT 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

ENT · Ear and audiology: mechanotransduction in hair cells

Sample item

Sound causes the stereocilia of an inner hair cell to bend toward the tallest row. What is the immediate ionic event?

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

The answer and the reasoning

B. Entry of potassium from the endolymph, causing depolarisation

Bending toward the tallest stereocilia opens mechanically gated channels at the tips. Endolymph is rich in potassium and has a positive potential, so potassium flows in and depolarises the cell, which opens calcium channels and releases glutamate. Bending the other way closes the channels.

Option by option

  • A. Efflux of chloride, causing hyperpolarisation

    Chloride efflux is not the transduction mechanism.

  • B. Entry of potassium from the endolymph, causing depolarisation (correct)

    Correct. Potassium is the main cation in endolymph and it carries the transduction current.

  • C. Entry of sodium from the perilymph, causing depolarisation

    Perilymph surrounds the base of the cell and does not bathe the stereocilia.

  • D. Entry of potassium, causing hyperpolarisation

    Entry of a cation depolarises the cell and cannot hyperpolarise it.

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 ENT questions

Questions about this ENT question

What is the answer to this ENT question?

The best answer is B, Entry of potassium from the endolymph, causing depolarisation. Bending toward the tallest stereocilia opens mechanically gated channels at the tips.

Why is "Efflux of chloride, causing hyperpolarisation" not the answer?

Chloride efflux is not the transduction mechanism.

Why is "Entry of sodium from the perilymph, causing depolarisation" not the answer?

Perilymph surrounds the base of the cell and does not bathe the stereocilia.

Why is "Entry of potassium, causing hyperpolarisation" not the answer?

Entry of a cation depolarises the cell and cannot hyperpolarise it.

What concept does this question test?

It tests Ear and audiology: mechanotransduction in hair cells in ENT. Endolymph is rich in potassium and has a positive potential, so potassium flows in and depolarises the cell, which opens calcium channels and releases glutamate. Bending the other way closes the channels.

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 Ear and audiology: mechanotransduction in hair cells?

Learn tuning fork results and audiogram patterns by sketching them. Then use the flashcards and the other ENT 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.