Cell injury and adaptation: disuse atrophy mechanism: practice question

A Pathology 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

Pathology · Cell injury and adaptation: disuse atrophy mechanism

Sample item

A limb immobilised in plaster for six weeks shows reduced muscle bulk. Which cellular mechanism contributes most to the loss of cell mass?

ACaspase-8 activation by Fas ligationBCalcium-mediated phospholipase activation and necrosisCAccumulation of misfolded protein in the endoplasmic reticulumDUbiquitin-proteasome degradation with autophagy

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

The answer and the reasoning

D. Ubiquitin-proteasome degradation with autophagy

Atrophy from disuse reduces protein synthesis and increases protein degradation. Cytoskeletal and myofibrillar proteins are tagged with ubiquitin and degraded by proteasomes, and autophagy removes organelles, so the cell shrinks without dying.

Option by option

A. Caspase-8 activation by Fas ligation
Fas-mediated caspase activation causes apoptosis, not simple cell shrinkage by atrophy.
B. Calcium-mediated phospholipase activation and necrosis
Calcium-driven enzyme activation causes necrosis, not graded atrophy.
C. Accumulation of misfolded protein in the endoplasmic reticulum
ER protein accumulation underlies the unfolded protein response and is not the main mechanism here.
D. Ubiquitin-proteasome degradation with autophagy (correct)
Correct. Increased proteasomal degradation and autophagy shrink the cell.

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.

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is D, Ubiquitin-proteasome degradation with autophagy. Atrophy from disuse reduces protein synthesis and increases protein degradation.

Why is "Caspase-8 activation by Fas ligation" not the answer?

Fas-mediated caspase activation causes apoptosis, not simple cell shrinkage by atrophy.

Why is "Calcium-mediated phospholipase activation and necrosis" not the answer?

Calcium-driven enzyme activation causes necrosis, not graded atrophy.

Why is "Accumulation of misfolded protein in the endoplasmic reticulum" not the answer?

ER protein accumulation underlies the unfolded protein response and is not the main mechanism here.

What concept does this question test?

It tests Cell injury and adaptation: disuse atrophy mechanism in Pathology. Cytoskeletal and myofibrillar proteins are tagged with ubiquitin and degraded by proteasomes, and autophagy removes organelles, so the cell shrinks without dying.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Cell injury and adaptation: disuse atrophy mechanism?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.