BBC Earth (Asia) - - Q & A -

In 2012 re­searchers blew puffs of air over cells cul­tured from the lin­ing of a hu­man nose to sim­u­late a sneeze. They found the cilia cells beat much faster for sev­eral min­utes. The beat­ing cilia clear away mu­cus and trapped germs, so sneez­ing may help quickly ‘re­boot’ the nose. In peo­ple with si­nusi­tis, the cilia don’t speed up like this, which might ex­plain why suf­fer­ers have pro­longed sneez­ing fits!

1. Nose

A sneeze be­gins when dust, chem­i­cals or a light touch stim­u­late the nerve end­ings of the trigem­i­nal nerve.

4. Di­aphragm

The re­flex forces a sud­den, deep in­take of breath. At this point the chain re­ac­tion is un­stop­pable and a sneeze is in­evitable.

2. Eyes

17-35 per cent of peo­ple also sneeze when ex­posed to bright light. This is known as Au­to­so­mal dom­i­nant, Com­pelling He­lio-Opthalmic Out­burst, or ‘ACHOO’.

5. Glot­tis

The glot­tis at the back of your throat squeezes shut as your di­aphragm con­tracts to build up pres­sure. Your eyes also squeeze shut.

3. Brain

The sig­nals travel to the ‘sneez­ing cen­tre’ in the lat­eral medulla of your brain. When they reach a crit­i­cal thresh­old, it trig­gers a sneeze re­flex.

6. Mouth and nose

The pres­sure is re­leased and air, mu­cus, dust and germs exit through the mouth and nose at up to 160km/h. This ejec­tion lasts just 150 mil­lisec­onds.

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