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Sneezing, this involuntary and sometimes resounding reaction, is much more crucial than a simple response to nasal irritation. It is, in reality, a vital defense mechanism for our body that the process of evolution has equipped us with to expel unwanted intruders and preserve the integrity of our respiratory tract.
We humans sneeze on average once or twice a day. Of course, this frequency can vary considerably from one individual to another and depends on several factors (allergies, individual condition, environment, etc.). This reflex is so common that we don't really pay attention to it anymore; what does science tell us about it ?
A thousand-year-old protective reflex
Over the centuries, sneezes have been shrouded in a halo of beliefs and superstitions. The first Christians sometimes perceived divine manifestations, sometimes diabolical tricks, while the ancient Greeks interpreted them as omens, favorable or harmful.
Nowadays, modern science has dispelled these myths by providing a clear physiological explanation: sneezing is an innate defensive act, aimed at ejecting any foreign substance seeking to infiltrate our body through the nasal passages. Cecelia Damask, specialist in otorhinolaryngology at Orlando ENT and Allergy, explains: “ Just as the skin protects us, one of the primary functions of the nose is to ensure our protection< /em> ”.
When unwanted elements like pollen, dust particles or viruses get into our sinuses, they cause irritation of the mucous membrane. This aggression triggers the release of chemicals that stimulate the trigeminal nerve, a major nerve responsible for facial sensations. The latter then transmits an electrical signal to the medulla oblongata, an essential component of the brainstem (structure that connects the brain to the spinal cord). In response, the brain initiates a physiological reflex aimed at neutralizing the potential threat: then comes the moment when you sneeze.
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A chain reaction for a big cleaning
The mechanism of sneezing is a process of remarkable complexity and liveliness. In a tiny instant, a series of actions occur: the eyelids close, the tongue presses against the palate, the diaphragm contracts in concert with the thoracic and abdominal muscles, while the vocal cords tighten to increase intrapulmonary pressure. Then, like a dam bursting under pressure, everything suddenly releases, propelling a powerful exhalation of air toward the mouth and nostrils.
200% Deposit Bonus up to €3,000 180% First Deposit Bonus up to $20,000The speed of the projected air can reach 150 km/h, carrying with it up to 40,000 droplets into the air up to eight meters away (see video above at about 3 minutes 40). “All this happens in a matter of seconds,” Damask says. ” This expels any foreign substance “.
However, sometimes a single sneeze is not enough to completely evacuate the intruders. In such cases, a series of sneezes may be necessary. As for the exact reason for this phenomenon, it still remains a mystery to science.
Various and sometimes strange triggers
While sneezing is primarily intended to purge the body of contaminants, it can also be triggered by stimuli that are sometimes much more unusual. For example, approximately 20 to 35% of the world's population can sneeze while staring at the sun, a phenomenon known as the “photic reflex” or “heliotropic sneeze”. Although this reaction is quite common, its exact cause remains unclear to scientists.
The most widespread hypothesis suggests an anomaly that would be located at the level of the nerve connections. It seems that a short circuit occurs between the optic nerve, which transmits visual information to the brain, and the trigeminal nerve. So, when a person is subjected to a significant change in light, such as going from darkness to light, the optic nerve would be overstimulated and send signals to the trigeminal nerve, involuntarily triggering the sneeze reflex.
Another, slightly less common trigger: food. Others may experience sneezing after a large meal, a reaction curiously named ” snatiation ,” a neologism of ” sneeze ” (éneru in English) and ” satiation ” (satiety). Some individuals even feel the need to clear their sinuses by sneezing after an orgasm or by simply thinking erotic thoughts.
If we could not sneeze, the consequences for the body would be disastrous. Without this reflex, these irritants could accumulate in the upper respiratory tract, potentially leading to more frequent and more serious infections, chronic inflammation, breathing difficulties or even more serious complications (pneumonia, severe allergic reactions, etc.). If the human species had not developed the sneeze reflex, it is highly probable that we would not exist in our current form, if at all.
- Sneezing is an involuntary reflex that expels irritating particles from the respiratory tract.
- Triggered by irritation of the nasal mucosa, sneezing involves a series of coordinated actions
- Although primarily associated with nasal irritants, sneezing can also be triggered by unexpected stimuli.
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