|MadSci Network: Anatomy|
Dear Al, To my knowledge, sneezing is NOT invariably accompanied by goosebumps, although it can be. I can only speculate why it might be. Sneezing releases a blast of air through the nasopharynx to clear it of irritating particles. This air rushes past 3 shelf-like bones, called nasal conchae, that project from the nasal septum in the midline of the nasal cavity. These bones are covered by a highly vascular epithelium that functions to transfer heat into incoming air. A rush of air could cause a sudden cooling of the blood vessels in this specialized air passage and an associated cooling of brain structures in their viscinity. Immediately above and behind the nasal conchae is the preoptic area of the hypothalamus, a brain area that regulates body temperature and can warm the body by causing shivering and piloerection (fluffing up of the hairs of the coat) in most mammals. If this brain area were suddenly cooled, it could "misread" the body temperature and initiate reflexes to warm the body temporarily. This is not as implausible as it sounds: in dogs and similar animals, the major way of cooling the brain is via panting through very large nasal conchae and removing heat from the blood vessels (the circle of Willis) at the bottom of the brain. Dogs have no other way of cooling themselves, since they do not sweat appreciably.
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