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How do tears protect the eyes? Explore the physiological miracle of tears!
We often hear the word "tears". It is not only an expression of emotion, but also plays an indispensable role in physiology. Tears are transparent liquid secreted by the lacrimal glands of our eyes. They contain various components such as water, electrolytes, proteins, lipids, and mucin, forming a protective film to maintain eye health. Tears are not only the carrier of emotions, they also have multiple physiological functions. Let us explore the mystery of tears together.
Chemical composition of tears
Tears are composed of three layers: lipid layer, aqueous layer, and mucus layer. The proportions of these tear components vary depending on the type of tear, the main ones being basal tears, reflex tears, and emotional tears. Studies have shown that emotional tears contain higher concentrations of stress hormones such as adrenocorticotropic hormone and the natural analgesic leucine enkephalin. This shows the biological importance of emotional tears in regulating stress hormone levels.
Drainage mechanism of tears
Tears secreted by the lacrimal glands flow through the main excretory ducts into the space between the eyeball and eyelids. When we blink, tears are evenly distributed across the surface of the eyeball. Excess tears flow into the tear lake, then enter the lacrimal sac through the puncta, and then flow into the nasal cavity through the nasolacrimal duct. Therefore, when emotions are intense, excessive tears may lead to a runny nose.
Types of tears
There are three main types of tears: basal tears, reflex tears and emotional tears. Basal tears are the basic fluid that keeps the eyes lubricated, while reflex tears are a response to stimuli, such as tears caused by the smell of turtle hearts or onions. Emotional tears are produced during times of heightened emotion and are thought to serve as an important network in emotional expression and stress relief.
The significance of tears in culture
In almost all human cultures, crying is closely associated with the act of tears running down the cheeks, accompanied by the characteristic sobbing sound. Emotional triggers are mostly caused by sadness or pain, but they can also be caused by anger, joy, and other strong emotions. Likewise, listening to music or watching certain media may trigger the flow of emotional tears. Social acceptance of crying varies from culture to culture. For example, some cultures view crying as a sign of immaturity, while Western cultures are relatively more tolerant.
The pathology of tears
One of the pathological conditions associated with tears is Bogolade syndrome, a rare result where poor repair of the facial nerve causes involuntary tearing. This condition can cause tears to be released along with saliva while eating, creating an embarrassing situation.
Modern understanding of tears
The contemporary understanding of tears is not only physical but also relates to mental health. Some schools of psychotherapy advocate that crying can help release stress and restore emotional balance. With the advancement of biomedicine, scientists are also exploring the physiological and psychological functions of tears in emotional states.
Ultimately, the multiple roles of tears are not only a physical necessity, but also deeply impact our lives on a psychological and cultural level. Is it possible that the protective mechanism provided by tears is more profound and complex than we imagined?
