Sneezing is a protective reaction of the body. With a sharp forced expiration, they are pushed out.
Not only people, but also animals can sneeze, while the mechanism for developing a reaction is the same as that of a person. The record holder for sneezing is the iguana, which thus gets rid of the sodium and potassium salts that accumulate in the body, without losing fluid.
Sneezing mechanism
Sneezing refers to unconditioned reflexes, that is, it is an innate reaction to stimuli controlled by the nervous system. The medulla oblongata is responsible for the process. Sneezing mechanism: getting on the mucous membrane irritants stimulate nerve endings. Impulses enter the trigeminal nerve, then into the respiratory center.
The brain gives a command by which a person takes a deep breath, filling the lungs as much as possible. The soft palate rises, the arches of the pharynx contract, the back of the tongue is adjacent to the hard palate, isolating the oral cavity. Muscles contract, intrauterine pressure rises, and air is expelled through the closed vocal cords. At the same time, a stream of air blows away irritants, cleansing the mucous membrane.
When sneezing, air exits through the glottis with a huge speed reaching 120 - 150 meters per second. In this case, mucus from the nasopharynx can scatter to a distance of 2 to 3 meters.
Interesting fact: when sneezing, a person always closes his eyes. The reason for this is the fact that the trigeminal nerve is involved in both processes, and the same part of the brain is responsible for them. At the time of sneezing, there is a spasm of the muscles responsible for blinking, so the eyes close.
Why does a person sneeze twice?
The reason why a person sneezes twice is the fact that a person cannot remove the irritant from the mucous membrane at a time, so the process repeats.
Also, dust or allergens entering the nasopharynx can cause swelling of the mucous membrane, which in turn irritates the receptors. After repeating several sneezes in a row, the brain gives a command to reduce their sensitivity, so the process stops.
Interesting fact: 12-year-old girl Donna Griffiths, who continuously sneezed for 977 days, became the record holder. The reason for this was never found out. Initially, the girl sneezed every minute, then every 5 minutes. The American June Clark had such an attack lasted 167 days.
Causes of sneezing
In addition to getting on the mucous membranes of external stimuli causing sneezing, there are other factors that trigger this process.
Viral diseases
As a result of the introduction of the virus, edema and mucous membrane occur, which leads to irritation of the receptors responsible for the process.
Allergy
When substances causing a negative reaction of the body (plant pollen, animal hair, chemicals) get on the nasopharynx tissue, histamine begins to be produced, which in turn leads to swelling of the mucous membrane and irritation of the receptors responsible for sneezing.
Hormone measurement
Often, nasal congestion and sneezing appear in women during pregnancy. The hormone progesterone is responsible for this.
Bright light reaching the retina
The cause of the light sneezing reflex has not yet been studied. It is known that this feature is observed in 35% of people and it is transmitted genetically.
Stressful situations
Some people sneeze when experiencing strong feelings, the reason for this is most likely the expansion or narrowing of the vessels in the nose.
Sudden changes in temperature
It is believed that the cause of the reflex in this case is irritation of the recipes in the nose with cold or hot air.
So why is a person sneezing twice? During a single sneeze, the mucous membrane is not completely cleaned, so the process is repeated until the stimulus comes out or the brain decreases the sensitivity of the receptors.
