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Carotid Body Afferent CN IX — FRCA Primary MCQ

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HardPhysiology - RespiratoryCarotid Body Afferent CN IXFRCA Primary

A patient has bilateral carotid-body denervation. Which ventilatory response is most specifically blunted?

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Correct answer: E — Rapid ventilatory response to acute arterial hypoxaemia

The best answer is “Rapid ventilatory response to acute arterial hypoxaemia”. Carotid bodies are the dominant peripheral chemoreceptors for acute hypoxaemia and signal through the glossopharyngeal sinus nerve. Central chemoreceptors retain a substantial response to CO2 through brain extracellular-fluid pH. Pulmonary stretch, airway-irritant and voluntary cortical responses use different afferent pathways and are not defined by carotid-body integrity.

Reference: RCoA, Primary FRCA syllabus: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf; Control of Ventilation in Health and Disease: https://pmc.ncbi.nlm.nih.gov/articles/PMC8894312/