Salivary Gland Innervation — MFDS Part 1 MCQ

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ModeratePhysiologySalivary Gland InnervationMFDS Part 1

During reflex salivation, activation of which receptor type on salivary gland acinar cells predominantly drives the bulk secretion of watery, high-volume saliva?

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Correct answer: E — Muscarinic acetylcholine receptor

Muscarinic acetylcholine receptors, predominantly M3 with a lesser contribution from M1, mediate parasympathetic stimulation of salivary acinar cells. Their activation raises intracellular calcium, promotes chloride-dependent fluid movement and produces the bulk of high-volume, watery saliva. Sympathetic alpha- and beta-adrenoceptor activation can also modify glandular secretion, but it is more strongly associated with exocytosis of stored proteins and does not principally drive bulk fluid output. Nicotinic acetylcholine receptors transmit impulses within autonomic ganglia rather than serving as the main secretory receptors on acinar cells. Histamine receptors are not the principal physiological mediators of reflex salivation.

Reference: Proctor GB, Carpenter GH. Regulation of salivary gland function by autonomic nerves. Autonomic Neuroscience. 2007;133(1):3-18. https://pubmed.ncbi.nlm.nih.gov/17157080/