Cardiovascular 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.

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Physiology · Cardiovascular physiology

Sample item

What causes the first heart sound?

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

The answer and the reasoning

A. Closure of atrioventricular valves

The first heart sound is produced by closure and tensing of the mitral and tricuspid valves at the onset of ventricular systole.

Option by option

  • A. Closure of atrioventricular valves (correct)

    Correct: S1 reflects atrioventricular valve closure.

  • B. Opening of semilunar valves

    Semilunar valve closure produces the second heart sound, not S1.

  • C. Atrial contraction

    Atrial contraction occurs before S1 and does not create the main first sound.

  • D. Venous return

    Venous return affects filling but does not directly produce S1.

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 A, Closure of atrioventricular valves. The first heart sound is produced by closure and tensing of the mitral and tricuspid valves at the onset of ventricular systole.

Why is "Opening of semilunar valves" not the answer?

Semilunar valve closure produces the second heart sound, not S1.

Why is "Atrial contraction" not the answer?

Atrial contraction occurs before S1 and does not create the main first sound.

Why is "Venous return" not the answer?

Venous return affects filling but does not directly produce S1.

What concept does this question test?

It tests Cardiovascular physiology in Physiology. The correct option holds because: Correct: S1 reflects atrioventricular valve closure.

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 Cardiovascular 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.