Blood and immunity: endothelial antithrombotic factors: 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 · Blood and immunity: endothelial antithrombotic factors

Sample item

Intact vascular endothelium prevents platelet adhesion to the vessel wall. Which pair of endothelial products inhibits platelet activation?

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

The answer and the reasoning

C. Prostacyclin and nitric oxide

Endothelial cells release prostacyclin and nitric oxide, which raise platelet cAMP and cGMP and inhibit adhesion and aggregation. They also express ecto-ADPase and thrombomodulin. When the endothelium is damaged, platelets meet subendothelial collagen and von Willebrand factor and are activated.

Option by option

  • A. Fibrinogen and thrombin

    Fibrinogen and thrombin promote clot formation and platelet activation.

  • B. Thromboxane A2 and ADP

    Thromboxane A2 and ADP come from platelets and promote aggregation.

  • C. Prostacyclin and nitric oxide (correct)

    Correct. Prostacyclin and nitric oxide raise platelet cyclic nucleotides and inhibit aggregation.

  • D. Von Willebrand factor and tissue factor

    Von Willebrand factor and tissue factor promote platelet adhesion and coagulation.

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 C, Prostacyclin and nitric oxide. Endothelial cells release prostacyclin and nitric oxide, which raise platelet cAMP and cGMP and inhibit adhesion and aggregation.

Why is "Fibrinogen and thrombin" not the answer?

Fibrinogen and thrombin promote clot formation and platelet activation.

Why is "Thromboxane A2 and ADP" not the answer?

Thromboxane A2 and ADP come from platelets and promote aggregation.

Why is "Von Willebrand factor and tissue factor" not the answer?

Von Willebrand factor and tissue factor promote platelet adhesion and coagulation.

What concept does this question test?

It tests Blood and immunity: endothelial antithrombotic factors in Physiology. They also express ecto-ADPase and thrombomodulin. When the endothelium is damaged, platelets meet subendothelial collagen and von Willebrand factor and are activated.

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 Blood and immunity: endothelial antithrombotic factors?

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.