Snot needs to be sticky to protect our airways from pollutants and pathogens. (Image credit: Makiko Tanigawa via Getty Images)
Most of the time, you're probably barely aware that you have mucus in your nose. However, when you have a cold or seasonal allergies, the thick mucus filling your nostrils suddenly makes it hard to breathe and distracts your thoughts.
But have you ever wondered why snot is so sticky?
Mucus can be uncomfortable when it blocks your nose, but its viscosity plays an important role: it helps trap and remove tiny irritants that enter your nasal passages along with the air you breathe in.
Without mucus, dust particles and harmful microbes could reach the lower respiratory tract and damage the delicate tissues of the lungs, Dr. Johannes Uys, a general practitioner at Broadgate General Practice in London, told Live Science via email. So the consistency of your nasal mucus is crucial to your immune defense, he added.
However, snot is not just a physical barrier to pollutants in the air; it also contains antiviral and antibacterial elements, including antibodies and proteins produced by the immune system to prevent infections. Snot also contains lysosomes, specialized cellular structures containing enzymes that break down invading pathogens, according to the medical resource StatPearls.
The consistency of your mucus can tell you a lot about your health when combined with other symptoms, Dr. Jay Lee, a board member of the American Academy of Family Physicians, told Live Science in an email.
“While normal mucus is clear and watery, cloudy or colorless mucus — such as green or yellow — can indicate a viral or bacterial infection,” he explained. This is due to the presence of dead white blood cells, a type of immune cell, and other debris left behind by the immune response. That’s why they change color during an infection.
“You may also notice a lot of congestion, as infections can cause inflammation of the membranes lining your nasal passages, causing the glands to produce more mucus,” Lee added. Not only does the mucus increase in volume, it also becomes thicker — again, due to a buildup of dead germs and cells that have arrived to fight the infection.
According to Lee, snot owes much of its stickiness and gel-forming ability to molecules known as mucins.
The structure of these sticky molecules resembles bottle brushes: They have a thin, elongated protein backbone with thick, bristly carbohydrate branches jutting out from it. This unique shape allows mucins to link together into a network that can resist shape changes. For this reason, the mucus in your nose can quickly return to its original state, even if its structure is temporarily disrupted when you cough or blow your nose, according to a 2018 review published in the journal Annual Review of Cell and Developmental Biology.
Uys noted that the chemical structure of mucins also allows them to bind significant amounts of water, which is what causes the thick, gelatinous texture of mucus.
Mucins serve as scaffolds for other active components in mucus, but they do much more. For example, these sticky molecules can interact with microbes that naturally reside within the mucus barrier, providing them with fuel. By supporting the growth of certain bacteria, mucins may also help prevent harmful microbes, such as the bacterium Staphylococcus aureus or the yeast Candida albicans, from sticking to the walls of your nose, the authors of the Annual Review noted.
So the next time you're dealing with a stuffy nose, remember the positive side of the situation: Your snot is helping you fight off an infection.
This article is for informational purposes only and does not constitute medical advice.
Sourse: www.livescience.com
