Reproduction: neonatal circulatory transition: 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 · Reproduction: neonatal circulatory transition

Sample item

After a term baby's first breaths, the foramen ovale closes functionally. Which change is responsible?

ASystemic vascular resistance falls when the cord is clampedBPulmonary vascular resistance falls, so left atrial pressure exceeds right atrial pressureCRight atrial pressure rises as umbilical venous return increases after birthDHigh arterial PO2 causes the foramen ovale to contract

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

The answer and the reasoning

B. Pulmonary vascular resistance falls, so left atrial pressure exceeds right atrial pressure

Lung expansion and oxygenation sharply reduce pulmonary vascular resistance, so pulmonary blood flow rises and more blood returns to the left atrium. Clamping the cord removes the low-resistance placental circuit, raising systemic resistance and left-sided pressures. The flap valve of the septum primum is pressed against the septum secundum, and anatomical fusion follows over months.

Option by option

A. Systemic vascular resistance falls when the cord is clamped
Clamping the cord raises, not lowers, systemic vascular resistance.
B. Pulmonary vascular resistance falls, so left atrial pressure exceeds right atrial pressure (correct)
Left atrial pressure exceeding right atrial pressure pushes the flap shut.
C. Right atrial pressure rises as umbilical venous return increases after birth
Umbilical venous return stops at clamping, so right atrial pressure falls.
D. High arterial PO2 causes the foramen ovale to contract
High PO2 and falling prostaglandins constrict the ductus arteriosus, not the foramen ovale.

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, Pulmonary vascular resistance falls, so left atrial pressure exceeds right atrial pressure. Lung expansion and oxygenation sharply reduce pulmonary vascular resistance, so pulmonary blood flow rises and more blood returns to the left atrium.

Why is "Systemic vascular resistance falls when the cord is clamped" not the answer?

Clamping the cord raises, not lowers, systemic vascular resistance.

Why is "Right atrial pressure rises as umbilical venous return increases afte…" not the answer?

Umbilical venous return stops at clamping, so right atrial pressure falls.

Why is "High arterial PO2 causes the foramen ovale to contract" not the answer?

High PO2 and falling prostaglandins constrict the ductus arteriosus, not the foramen ovale.

What concept does this question test?

It tests Reproduction: neonatal circulatory transition in Physiology. Clamping the cord removes the low-resistance placental circuit, raising systemic resistance and left-sided pressures. The flap valve of the septum primum is pressed against the septum secundum, and anatomical fusion follows over months.

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 Reproduction: neonatal circulatory transition?

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.