When something peculiar to the body enters the nostrils, or when there is swelling on the nose’s internal surface for some reason, the sensory cells in the nostrils will send a message of alarm to the brain. The message is couriered by a nerve called the trigeminal to the center of the brain, which controls the person’s breathing. The brain would then have to respond quickly to throw out the foreign substance in the nostrils before it can enter the lungs, which are mostly made of the very delicate mucous membrane. One important point to keep in mind during this process is that the lungs do not inflate or subside, and it is the diaphragm, through its action of contraction and flattening during inhalation, that causes the chest to expand. Furthermore, through the action of relaxation and rising during exhalation, the diaphragm causes the chest to subside.
At the command of the brain, the sneezing occurs when the diaphragm contracts considerably, thus allowing the lungs to breathe in a great quantity of air. After the said action, the diaphragm relaxes, although it relaxes with suddenness rather than its normal and slow way of relaxing its muscles. The resulting exhalation of the diaphragm causes a sudden noisy burst of air, and the moisture on the nose and mouth expels air at a maximum speed of 165 kilometers per hour, which is quite fast. The foreign particles or mucous logged in nostrils or windpipe are then thrown out in that burst of air, and its speed can be compared with running a vacuum cleaner in reverse. In an average sneeze, about 5,000 particles of mucous and moisture are thrown out up to 4 meters in length.
Histamines and the Muscles Involved in Sneezing
Histamine is a compound in the body that is responsible for controlling immune responses. When a foreign particle enters the nostrils, the histamines will irritate the nerve cells found on the nose, and these nerve cells will then send a signal to the brain that there is an irritant in the nostrils. The brain will then “contact” the trigeminal nerve network, or the system of nerves found on the eyes, nose, and jawline, and will signal it to begin sneezing.
The same signal that the brain sent to the trigeminal nerves will also be sent to the nerves on the tracheal muscles (lungs) and the pharyngeal muscles (pharynx) to assist with the sneezing by creating a large opening to allow air to burst through the nostrils. Once the sneezing is initiated, the other muscles on the body near the affected organs will have a reflexive response to stabilize the person’s position.
Infectious Aerosol Droplets
If the nostrils are irritated by an infectious foreign particle like a virus, the same sneezing process occurs, but the aerosol droplets that the nose sneezes will have the foreign particle attached to it. These droplets will then turn infectious, and other people who caught the droplets in their bodies may become infected with the virus once it gets to another opening, such as the mouth or the nose.
The sneezing process is one of the reasons why colds and other nasal-related infectious illnesses are quite common, as most people would be unable to control their sneezing, thus letting the aerosol droplets fall on the ground or another person. Because of this dilemma, it is recommended for people who have colds to always wear a face mask so that they won’t infect other people with their viral illness.
A common face mask, which is sometimes referred to as a surgical mask, is effective in preventing the spread of the aerosol droplets in the air. However, studies suggest that there are better masks to wear in order to stop the droplets from going out or even to prevent other people from infecting the wearer. One of these masks is the N95, a facepiece respirator developed by the company 3M in 1972. The same company still manufactures N95 masks today, with most people even saying that 3M’s mask is the only real N95 in the market, as there are some fakes or counterfeits that uses the company’s same design, but the materials used to make the product are different.
More reading:
- Sneeze (Wikipedia)