Why do we sneeze?

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WASHINGTON. August 18. KAZINFORM Sure, they blast out germs and other unwanted intruders, but sneezes have another, just discovered purpose, a new study says.

When we breathe in foreign particles, sensors in our noses and sinuses detect the objects. The sensors signal the cilia-tiny, hairlike paddles that line our nostrils and sinuses-to move to expel the irritants.

This process is "always idling at first gear," with the cilia ready to spring into action when needed, said study co-author Noam Cohen , an otolaryngologist-ear, nose, and throat specialist-at the University of Pennsylvania and the Philadelphia VA Medical Center, National Geographic News reports.

The study found that the burst of air produced by a sneeze not only clears nasal passages but also triggers the cilia sensors to kick the paddles into high gear for an extended period-about a couple minutes-Cohen said.

In that sense, a sneeze works by "resetting the system-like Control-Alt-Delete" on a PC, he said.

The study highlights what an "underestimated organ" the nose is, especially in terms of keeping us healthy, added Stella Lee, an otolaryngologist at the University of Pittsburgh School of Medicine.

(Also see "Why Do We Yawn? It May Keep Us From Getting Hot-Headed." )

How they deconstructed the sneeze

Cilia-which resemble a "constantly moving shag carpet" under the microscope-propel potentially harmful material out of our lungs and either up to our nostrils to be expelled or down to our gullets, where stomach acid zaps any harmful organisms or particulate matter, Lee said.

For cilia to work, they need mucus-and our nose delivers, producing about a liter (about four cups) a day, most of which we swallow.

People with sinusitis and genetic disorders such as cystic fibrosis have trouble clearing out mucus, even though they sneeze a lot.

The seeming contradiction made Cohen and colleagues wonder whether sneezing has a role in getting cilia to clear out mucus-and whether that process was somehow impaired in sinusitis patients.

The team took cells from the nostrils of healthy people as well as sinusitis patients. The researchers grew the cells in an incubator for several weeks, until the cells formed the same type of lining that's in our sinuses.

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