Question 1. When do they appear? There are several options, I remember as a child, in winter you play hockey and suddenly there is something salty glass from your nose in your mouth. I ran it over the upper lip as a hand and continue to play. The body is hot and the air is cold, so the body produces this fluid to protect the inner region of the nose from hypothermia and at the same time warms the inhaled air. Passes quickly when indoors and the ambient temperature rises. In some conditions, inflammation of the airways usually causes snot. Here snot already perform a different function, they include enzymes that help the body cope with pathogenic microbes. The treatment process causes the snot to thicken to a hard consistency, which are called boogers. Some chemical inhalation aerosols also cause nasal leakage and this is a defensive reaction to aggressive environments. This liquid dissolves some part of the aggressive environment and flows out of the nose. As an example: tear gas, it not only knocks liquid out of the eyes, but also starts flowing from the nose. There may be other causes of snot formation.
Snot is formally called "nasal mucus", but in science - "muconasal secret". Snot is usually understood as liquid nasal mucus, while dry nasal mucus is called goats, although these concepts are often confused.
Nasal mucus is called muconasal secretion, as it is formed on the mucous membrane of the nasal cavity, which is otherwise called the mucous nasal membrane.
The mucous membrane secretes water, salts (mainly sodium chloride and ammonium chloride ) and mucin. Mucin, or mucins, or mucoproteins, are substances that give a gel-like consistency to all secrets of any mucous membranes. In addition, since the mucous membrane is of epithelial origin, like the skin, it can slough off, so the muconasal secretion contains epithelial cells. Finally, the muconasal secretion contains lysozyme, an antibacterial enzyme that destroys the murein of the bacterial cell walls.
The muconasal secretion is needed to retain and destroy pathogens and allergenic dust by fermenting with lysozyme passing through the nasal cavity during breathing. In addition, nasal mucus moisturizes the air you breathe.
The cilia lining the nasal cavity move muconasal secretions down to the pharynx, so it usually flows down to the throat and is swallowed. In fact, the body was designed to swallow snot, so there is nothing bad or harmful in eating it (about 40% of people continue to do this in adulthood), and in childhood it even helps to form a strong immune system. There is an exception: snot should not be eaten during colds. If mucus is overproduced to carry germs out of the body with it, it flows out through the nasal openings. If mucus is produced close to the nasal openings, it quickly loses moisture and dries up.