Cardiovascular system: fetal blood streaming: 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 system: fetal blood streaming

Sample item

In a normal late-gestation fetus, which organs receive blood with the highest oxygen content?

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

The answer and the reasoning

A. Heart and brain

Well-oxygenated umbilical venous blood passes through the ductus venosus into the inferior vena cava and is streamed across the foramen ovale into the left atrium. The left ventricle then supplies the coronary and cerebral arteries before blood mixes with the desaturated flow from the ductus arteriosus. Lower body organs receive blood that has been mixed distal to the ductus.

Option by option

  • A. Heart and brain (correct)

    Correct. Ductus venosus blood is streamed across the foramen ovale to the left heart, which feeds the coronary and cerebral vessels first.

  • B. Lungs and adrenal glands

    Most right ventricular output bypasses the lungs, and the adrenals are supplied from the mixed descending aortic blood.

  • C. Liver and kidneys

    The liver is partly bypassed by the ductus venosus and the kidneys receive mixed blood from the descending aorta.

  • D. Lower limbs and gut

    These territories are supplied by the descending aorta, which carries blood already mixed with the desaturated ductus arteriosus flow.

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, Heart and brain. Well-oxygenated umbilical venous blood passes through the ductus venosus into the inferior vena cava and is streamed across the foramen ovale into the left atrium.

Why is "Lungs and adrenal glands" not the answer?

Most right ventricular output bypasses the lungs, and the adrenals are supplied from the mixed descending aortic blood.

Why is "Liver and kidneys" not the answer?

The liver is partly bypassed by the ductus venosus and the kidneys receive mixed blood from the descending aorta.

Why is "Lower limbs and gut" not the answer?

These territories are supplied by the descending aorta, which carries blood already mixed with the desaturated ductus arteriosus flow.

What concept does this question test?

It tests Cardiovascular system: fetal blood streaming in Physiology. The left ventricle then supplies the coronary and cerebral arteries before blood mixes with the desaturated flow from the ductus arteriosus. Lower body organs receive blood that has been mixed distal to the ductus.

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 system: fetal blood streaming?

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.