Cardiovascular system: neurogenic orthostatic hypotension: 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: neurogenic orthostatic hypotension

Sample item

A 58-year-old man with long-standing diabetes feels faint on standing. Supine blood pressure is 140/85 mmHg and heart rate 78 per minute. After three minutes standing, blood pressure is 95/60 mmHg and heart rate is 80 per minute. Which feature of this response points to a failed reflex rather than simple volume loss?

AVenous pooling of blood in the legs on standingBA fall in pressure on standing in the first placeCAlmost no rise in heart rate despite a large fall in pressureDA reduction in cardiac output after standing

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

The answer and the reasoning

C. Almost no rise in heart rate despite a large fall in pressure

On standing, about 500 mL of blood pools in the legs, venous return and stroke volume fall, and the baroreflex normally raises heart rate and vascular tone. A large pressure fall with a fixed heart rate indicates autonomic failure, as in diabetic neuropathy. In hypovolaemia the reflex is intact and the heart rate climbs.

Option by option

A. Venous pooling of blood in the legs on standing
Venous pooling occurs in every standing person and is not abnormal in itself.
B. A fall in pressure on standing in the first place
Pressure falls on standing in both volume depletion and autonomic failure, so this does not discriminate.
C. Almost no rise in heart rate despite a large fall in pressure (correct)
Correct. A fixed heart rate shows the baroreflex efferent response has failed.
D. A reduction in cardiac output after standing
Cardiac output falls transiently in all people on standing, so this does not discriminate.

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 C, Almost no rise in heart rate despite a large fall in pressure. On standing, about 500 mL of blood pools in the legs, venous return and stroke volume fall, and the baroreflex normally raises heart rate and vascular tone.

Why is "Venous pooling of blood in the legs on standing" not the answer?

Venous pooling occurs in every standing person and is not abnormal in itself.

Why is "A fall in pressure on standing in the first place" not the answer?

Pressure falls on standing in both volume depletion and autonomic failure, so this does not discriminate.

Why is "A reduction in cardiac output after standing" not the answer?

Cardiac output falls transiently in all people on standing, so this does not discriminate.

What concept does this question test?

It tests Cardiovascular system: neurogenic orthostatic hypotension in Physiology. A large pressure fall with a fixed heart rate indicates autonomic failure, as in diabetic neuropathy. In hypovolaemia the reflex is intact and the heart rate climbs.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: neurogenic orthostatic hypotension?

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.