Colorado scientists have discovered a new type of cell in the nose that explains why so many of us cry when chopping onions, itch at the whiff of fresh-cut grass and gasp when a can of soda sprays mist into our schnozzes.
Researchers identified “chemosensory cells,” located at the entrance to the nose of animals and humans, that help us sense irritating and possibly dangerous chemicals in the environment, according to research published this week.
There are about 12 types of cells known to help us smell, taste, feel, touch and see, said Diego Restrepo, a biologist at the University of Colorado Denver School of Medicine’s Rocky Mountain Taste and Smell Center.
“This is a new one,” said Restrepo, a co-author of the new study, published in the March issue of the Journal of Neurophysiology. “It’s not very often this happens. It is pretty cool.”
Restrepo and colleagues in Colorado, Maryland and New York used mice to investigate how inhaled scents — such as onions, ammonia and pollutants — trigger the trigeminal nerve system. That nerve system helps the brains perceive touch, temperature and pain.
Researchers had assumed that the inhaled chemical irritants directly stimulated the trigeminal nerve, said Tom Finger, a biologist at CU’s taste and smell center and co-author of the study.
It turned out chemosensory nerve cells near the front of the nose responded to irritating chemicals and then relayed signals to the trigeminal nerve.
Put together, Finger said, the system creates the type of reflex that makes you quickly stop breathing — or even gag — when you smell something nasty.
Finger said similar types of chemosensory cells have been found in water-dwellers, but researchers didn’t understand the cells’ function — “until now.”
