In the rich emotional universe of human beings, tears are one of the most unique stars, both as an expression of emotion and as evidence of a physiological phenomenon. But, have you ever wondered why we shed tears? Let's dive into the science behind tears and unravel this seemingly simple yet complex physiological mystery.
Tears, these little things that are crystal clear, are not just synonymous with sadness. They are not just tear-jerking testimonies of the theme song of "Titanic", nor are they just the irrepressible sadness of parting. In fact, tears are a unique and magical presence in our body, and they have many functions and forms.
With every blink, our eyes are encased in a thin layer of fluid, which is the basal tear. They work constantly, silently, to keep the eyes moist, provide nutrients, and form a line of defense that protects the eyes from dust and microorganisms. Imagine how dry and fragile our eyes would be without this layer of fluid.
When chopping onions, or accidentally getting into the sand, you will find that tears start to flow uncontrollably. These are reflex tears, and their task is to rinse the eyes, flushing irritants and foreign bodies out of the body. Their yield far exceeds that of basal tears, which is enough to clean and protect the eyeballs.
Finally, and best known are emotional tears, which welled up when we felt sad, happy, or extremely moved. Emotional tears contain more protein than basal tears, and scientists believe this may help relieve stress, as we usually feel more relaxed after tears.
So, where do these tears come from? They begin in our lacrimal glands, located above the outside of each eye. When the lacrimal glands receive signals from the brain, they begin to produce tears, whether to lubricate the eyes, remove irritants, or respond to changes in mood.
After the tears pass through the surface of the eye, they pass through the tiny tear ducts and enter the nasolacrimal ducts and eventually reach our nasal cavity. That's why we usually need to blow our nose when weeping, because tears actually flow into our noses.
When we think of tears, the first thing that probably comes to many people's minds is their salty taste and moist touch. However, this is only the surface of tears. In fact, tears are far more complicated than we think. It is not just a substance made from a simple mixture of water and salt, but a liquid full of mysteries and complex components.
Tears are rich in water, oil, protein, metabolic waste, and various electrolytes. These ingredients play a vital role in maintaining the normal function of the eye. Water is the main component of tears, it provides a moist environment for tears, helping to maintain the comfort of the eyes. At the same time, water also provides a carrier for the other components in the tears, allowing them to be evenly distributed on the surface of the eyeball.
Tears are a complex liquid whose composition plays an important role in maintaining eye health. Understanding the composition and function of tears not only helps us better protect our eyes, but also helps us understand other aspects of the body.