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the wonder of the nostril: from scent detector to bacteria fighter
we do about 75 per cent of our breathing through one nostril and 25 per cent through the other with the dominant nostril alternating every couple of hours.
nov 5 2021
3 minute read
a runny nose is one way the body tries to get rid of bacteria. getty
one of the defining features of the human face, the nose is an oft ignored and barely discussed neighbour of other facial features like the eyes, hair and lips which tend to get much more hype and attention.
in fact, the nose is such an afterthought that our brains literally ignore it despite it being in our field of vision 100 percent of the time.
it turns out we kind of have two noses. according to bbc’s science focus magazine , “we smell using sensory cells high up in the nose, and some odour chemicals need more time than others to bind to these receptors. so, a low-airflow nostril gives slow-acting odours more time to be detected, giving us a greater range of smell.”
this process is part of the human nasal cycle , a phenomenon characterized by congestion of the nasal airway alternating from the left nostril to the right, back and forth.
one nostril rules
essentially, at any given moment you are breathing out of one nostril more than the other. we do about 75 per cent of our breathing through one and 25 per cent through the other — to be precise — with the dominant nostril alternating every couple of hours, according to a
2016 study
in the journal plos one.
interestingly, the study also found a correlation between right handedness and a dominant left nostril.
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body position was also a heavy influence on the nasal cycle, according to the same study. lying on your right or left was associated with greater air flow in the opposite side’s nostril. this finding is also likely to explain why the nasal cycle was far more noticeable to subjects during sleep. though the cycle alternations happened more often while the subjects were awake, they were more pronounced when lying down.
guardians against bacteria
the nasal cycle isn’t the only function of the nostrils, though. other than being the area where nerve cells detect smells, the
nostrils also act as guardians for our lungs
from dust, pollen, dirt and other particles would otherwise end up in our airways. little hair-like organelles called
cilia
trap the debris in the mucous within the nose, where it is eventually swallowed.
when we get sick, it’s sometimes because pathogens have made it past the nostril’s defences to set up shop. according to a popular science article , the immune system then steps up to protect the body.
“small proteins called cytokines deploy t cells and b cells to seek out and destroy the pathogens. those same protein messengers instruct cells in the nose to generate more mucus in order to clear the cell lining of other potentially harmful bacteria or viruses,” according to the story. “as mucus goes into overdrive, your mucus lining swells and your nasal cavity fills with excess fluid.”
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the result of that process? a runny nose.
but sickness isn’t the only reason your nose might be stuffed up. it could also be due to congestion because of allergies, exposure to irritants or some chemicals, or the sign of a deviated septum .
nasal decongestant sprays or exercise can help to open up both airways if the nasal cycle isn’t quite working normally. there is even evidence that sex can improve nasal function.
with all of these cool features, it’s probably time we give props to our nostrils for all they do for us — after all, the ability to detect smells while keeping us safe from germs is well, nothing to sniff at.
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