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.
Crying or weeping is increased lachrymation due to strong emotion, pain, or irritation around the eye. In humans, emotional or pain-induced tearing can be accompanied by sobbing - cough-like, convulsive breathing, sometimes involving spasms of the whole upper body.
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.
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.
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 most 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
Societal and literary aspects