Microcirculation: lymphatic function: 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 · Microcirculation: lymphatic function

Sample item

A 40-year-old man from an endemic area has gross swelling of the leg after recurrent lymphatic filariasis. Why does protein-rich fluid accumulate in the interstitium?

AVenous reabsorption of protein is blocked by raised oncotic pressureBLymphatics are the only route that returns filtered plasma protein to the circulationCCapillaries absorb excess protein back from the interstitiumDLymph vessels secrete protein into the interstitium

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

The answer and the reasoning

B. Lymphatics are the only route that returns filtered plasma protein to the circulation

Capillaries leak a small amount of albumin, and the lymphatic system is the only means of returning this protein, and excess filtered fluid, to the blood. When lymph channels are obstructed, protein accumulates and raises interstitial oncotic pressure, drawing in more fluid. The oedema is therefore protein-rich and firm.

Option by option

A. Venous reabsorption of protein is blocked by raised oncotic pressure
Venous reabsorption of protein is not a significant route, so blocking it is not the explanation.
B. Lymphatics are the only route that returns filtered plasma protein to the circulation (correct)
Correct. Lymph vessels clear interstitial protein, and obstruction traps it.
C. Capillaries absorb excess protein back from the interstitium
Capillaries do not reabsorb large amounts of protein; this is the lymphatic function.
D. Lymph vessels secrete protein into the interstitium
Lymphatics drain protein; they do not secrete 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.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is B, Lymphatics are the only route that returns filtered plasma protein to the circulation. Capillaries leak a small amount of albumin, and the lymphatic system is the only means of returning this protein, and excess filtered fluid, to the blood.

Why is "Venous reabsorption of protein is blocked by raised oncotic pressure" not the answer?

Venous reabsorption of protein is not a significant route, so blocking it is not the explanation.

Why is "Capillaries absorb excess protein back from the interstitium" not the answer?

Capillaries do not reabsorb large amounts of protein; this is the lymphatic function.

Why is "Lymph vessels secrete protein into the interstitium" not the answer?

Lymphatics drain protein; they do not secrete it.

What concept does this question test?

It tests Microcirculation: lymphatic function in Physiology. When lymph channels are obstructed, protein accumulates and raises interstitial oncotic pressure, drawing in more fluid. The oedema is therefore protein-rich and firm.

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 Microcirculation: lymphatic function?

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.