Salivary Volume — MFDS Part 1 MCQ

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ModeratePhysiologySalivary VolumeMFDS Part 1

In a healthy adult, what is the approximate total volume of whole saliva secreted over 24 hours, including resting and stimulated secretion?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — 0.5–1.5 litres

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

The correct answer is A. A healthy adult produces approximately 0.5–1.5 litres of whole saliva over 24 hours, with about 1 litre commonly used as a representative value. Total output includes predominantly unstimulated secretion between meals together with increased secretion during eating and other stimulation; it varies with hydration, circadian rhythm and autonomic activity. Options B and E are substantially below the usual daily physiological output. Option C begins at the approximate upper end of the normal range and therefore overestimates typical production, while option D is several times greater than expected.

Reference: Nonaka T, Wong DT. Saliva diagnostics: Salivaomics, saliva exosomics, and saliva liquid biopsy. Journal of the American Dental Association. 2023;154(8):696–704. https://surreydownshealthandcare.nhs.uk/swallowing-difficulties