Tears
Tears
Tears (/tɪərz/) are a clear liquid secreted by the lacrimal glands (tear gland) found in the eyes of all land mammals (except for goats and rabbits). Their functions include lubricating the eyes, removing irritants and aiding the immune system. Tears can be triggered by a range of emotions including happiness, sadness, or pain.
Etymology
The word "tear" comes from the Old English tēar, which is akin to the Old High German zahar, the Latin dacrima, and the Greek dákry.
Types of Tears
There are three types of tears: basal, reflex, and emotional.
- Basal tears are omnipresent in our eyes. These constant tears are what keep our eyes from drying out completely.
- Reflex tears are formed when the eyes come into contact with irritants, such as when chopping onions or when getting something in the eye.
- Emotional tears are produced in response to strong emotions, such as sorrow, joy, or frustration.
Composition
Tears are made up of water, lipids, lysozyme, lactoferrin, lipocalin, glycoproteins, and electrolytes. Each component plays a role in promoting eye health, fighting off infectious agents, and ensuring a smooth, clear optical surface.
Production and Drainage
Tears are produced by the lacrimal gland and are drained through the lacrimal punctum. When the production and drainage of tears are not balanced, dry eyes or watery eyes can occur.
Related Terms
- Lacrimation: The process of producing tears.
- Lacrimal apparatus: The structures that produce and drain tears.
- Dry eye syndrome: A condition that occurs when the eyes do not produce enough tears or when the tears evaporate too quickly.
- Epiphora: An overflow of tears onto the face.
External links
- Medical encyclopedia article on Tears
- Wikipedia's article - Tears
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