In a word u can say-[COLOR="Blue"]Crying:'( is the production of tears in response to an emotion in humans.[/COLOR]


the word tears can be defined by-
[COLOR="blue"]Tears :'(are a liquid process of lacrimation to clean and lubricate the eyes. The word lacrimationmay also be used in a medical or literary sense to refer to crying. Strong emotions, such as sorrow or elation, may lead to crying. The process of yawning may also result in tearing. Although most land mammals have a lacrimation system to keep their eyes moist, humans are the only animal generally accepted to cry emotional tears.[/COLOR]

types of tear-
[COLOR="blue"]1. Basal tears::'( In healthy mammalian eyes, the cornea is continually kept wet and nourished by basal tears. They lubricate the eye and help to keep it clear of dust. Tear fluid contains water, mucin, lipids, lysozyme, lactoferrin, lipocalin, lacritin, immunoglobulins, glucose,urea, sodium, and potassium. Some of the substances in lacrimal fluid fight against bacterial infection as a part of the immune system.

2. Reflex tears: :'(The second type of tears results from irritation of the eye by foreign particles, or from the presence of irritant substances such as onion vapors, tear gas or pepper spray in the eye's environment. These reflex tears attempt to wash out irritants that may have come into contact with the eye.

3. Crying or weeping (psychic tears)::'( The third category, generally referred to as crying or weeping, is increased lacrimation due to strong emotional stress, depression or physical pain. This practice is not restricted to negative emotions; many people cry when extremely happy. In humans, emotional tears can be accompanied by reddening of the face and sobbing — cough-like, convulsive breathing, sometimes involving spasms of the whole upper body. Tears brought about by emotions have a different chemical make up than those for lubrication; emotional tears contain more of the protein-based hormones prolactin,adrenocorticotropic hormone, and leucine enkephalin (a natural painkiller) than basal or reflex tears. The limbic system is involved in production of basic emotional drives, such as anger, fear, etc. The limbic system, specifically the hypothalamus, also has a degree of control over the autonomic system. The parasympathetic branch of the autonomic system controls the lacrimal glands via the neurotransmitter acetylcholine through both the nicotinic and muscarinic receptors. When these receptors are activated, the lacrimal gland is stimulated to produce tears. [/COLOR]

dear readers all the informations r collected from internet & just a little bit modifide by me.
thanks for reading.