Baroreceptor Reflex — FRCA Primary MCQ

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EasyPhysiology - CardiovascularBaroreceptor ReflexFRCA Primary

In a healthy adult with intact autonomic reflexes, which immediate baroreceptor reflex response is expected following a sudden increase in arterial blood pressure?

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Reveal the answer and explanation

Correct answer: E — Decreased heart rate and vasodilation

Explanation lettering: B = shown as A · D = shown as B · A = shown as C · C = shown as D

The correct answer is E. A sudden rise in arterial pressure increases stretch and firing of the carotid sinus and aortic arch baroreceptors. Their afferents travel through cranial nerves IX and X to the nucleus tractus solitarius. This increases cardiac vagal activity and inhibits sympathetic outflow, causing bradycardia, reduced cardiac contractility and vasodilation through withdrawal of sympathetic vasoconstrictor tone. Parasympathetic activity does not directly dilate most systemic vessels. Options A and B each contain one response in the wrong direction; D describes the response to a fall in pressure. Option C could occur with severe baroreflex or autonomic failure but not in the healthy adult specified.

Reference: Biaggioni I, Shibao CA, Jordan J. Evaluation and Diagnosis of Afferent Baroreflex Failure. Hypertension. 2022;79(1):57–59. Figure: baroreflex-mediated regulation of cardiovascular function. https://pubmed.ncbi.nlm.nih.gov/34878899/