We all know that tears are secreted by lacrimal glands. What you don't know is that the lacrimal gland not only secretes tears in "deep affection", but also works all the time. Part of the tears secreted by the lacrimal gland will be evaporated, and the other part will flow into the nose along a tube called the lacrimal duct. The nose has the function of "humidifying" the air, and this little tear that flows into the nose is often unnoticed.

When people are emotional, the crossed nervous system will be very excited, and the secretion of lacrimal glands that stimulate the eyes will be strengthened, resulting in a large number of tears, which will make people "burst into tears." The blood flow of tears cannot be quickly digested and absorbed by the lacrimal gland, so it is certain that unnecessary tears will reach the nasal cavity according to the continuous nasolacrimal duct under the lacrimal gland, driven by the theme activities around the eyes. Biologists have found that in our tears, 99% is water, 1% is solid, and more than half of this solid is salt.

If there are too many tears, stay in the nose for too long, and the liquid containing salt and residue stimulates the nasal mucosa, everyone will naturally feel sour nose. At the same time, after the tears reach the nasal cavity, the secretion of irritating nasal mucosa is strengthened, leading to excessive nasal discharge and runny nose. Excessive secretion of nasal mucosa leads to nasal edema, which in turn leads to edema and obstruction of nasopharyngeal tube. Therefore, sniffing will occur. Some experts and scholars have also shown that when the secretion of tears increases sharply, the nasolacrimal duct has long been unable to consider the speed of tears discharge. If the nasolacrimal duct is overloaded, the nose will be sour.

Under sad circumstances, the endocrine function of the "five internal organs" of the human body is damaged. Thus changing the whole process of biochemical metabolism such as "glycolytic pathway" and "pentose phosphate pathway"; Initially, it should cause the metabolism of CO2 and H2O, and as a result, the substance becomes ethanol or lactic acid. This secretion escapes outward according to the safe passage exchange between the body and the external conditions, such as the "seven orifices" of the mouth, nose and eyes. However, although the taste bud effector on the tongue is relatively developed, the nose is the primary safe passage for exhaling steam when you are sad, and it is also the key human organ for "taste". This acid-base metabolite stimulates the nasal mucosa, making people feel "sour nose", and at the same time, a lot of tears will gush out, which is convenient for removing waste.