Tears
Tears trickling down the cheeks
Lachrymation refers to the body's process of producing tears, which are a liquid produced by the body to clean and lubricate the eyes. The word lachrymation may also be used in a medical or literary sense to refer to crying.
Lachrymal glands are located above and beside each eye, behind the eyelid. When the eyelid blinks, a small amount of lachrymal fluid is pulled from the glands. Strong emotion causes the lachrymal glands to constrict and emit tears.
Tears flow from the eyes through lachrymal ducts located at the inner corner of each eye. Lachrymal fluid often flows into the nasal duct, causing the nose to run.
There are three basic types of tears. In healthy mammalian eyes, tears continually bathe the cornea. The tear fluid contains water, mucin, lipids, lysozyme, immunoglobulins, glucose, urea, sodium, and potassium. This fluid helps to clear the eye of foreign particles such as dust, and to keep the eyes from drying out. Some of the substances in lachrymal fluid fight against bacterial infection as a part of the immune system.
The second type of tears results from irritation to the eye brought about by particles lodged in the eye or gases and chemicals that cause irritation, such as tear gas or pepper spray. These tears attempt to clear any particle or foreign substance matter that may have gotten into the eye.
The third category, also referred to as crying or weeping, is increased lachrymation due to strong stress. In humans, emotional or pain-induced tearing can be accompanied by sobbing - cough-like, convulsive breathing, sometimes involving spasms of the whole upper body. Crying can reslt from overwhelmning positive emotion as well. Humans are the only animals that have been proven to cry for emotional reasons. Some studies have suggested elephants and gorillas may cry. Tears brought about by emotions have a very different chemical make up than those for lubircation. They are filled with hormones, and it now believed tears are a method of expelling excess hormones from the body.
Most mammals will produce tears in response to extreme pain or other stimulus, but crying as an emotional reaction is considered by many to be a uniquely human phenomenon, possibly due to humans' advanced self-awareness. In nearly all cultures, crying is seen as a specific act associated with tears trickling down the cheeks and accompanied by characteristic sobbing sounds. Emotional triggers are most often anger and grief, but crying can be triggered by sadness, joy, fear, humor, et cetera.
In many cultures, crying is associated with babies and children. Some cultures consider crying to be undignified and infantile, casting aspersion on those who cry publicly. In most Western cultures, it is more societally acceptable for women to cry than men. In other cultures, the reverse is true.
Many religions describe gods or prophets as crying. The shortest verse in the Christian Bible (in English) is simply: "Jesus wept." Jade is sometimes known as tears of the Buddha. The Koran describes Mohammed crying, and proclaiming: "This is an expression of the tenderness and compassion, which the Lord hath put into the hearts of His servants."Physiology
Types of Tears
Societal aspects