Tear

General Information
Latin	Lacrima
Greek
TA98
TA2
FMA
Details
System	Lacrimal system
Artery
Vein
Nerve
Lymphatic drainage
Precursor
Function	Lubrication of the eye, antibacterial, emotional expression
Identifiers
Clinical significance
Notes

A tear is a drop of fluid secreted by the lacrimal glands located in the upper outer region of the eye. Tears are essential for the overall health of the eye and for clear vision. They serve multiple functions, including lubrication, providing nutrients to the eye, and aiding in the removal of foreign substances.

Composition

Tears are composed of water, electrolytes, proteins, lipids, and mucous. They also contain lysozyme, an enzyme that has antibacterial properties, helping to protect the eyes from infection.

Types of Tears

There are three main types of tears:

• Basal tears: These are continuously produced to keep the eye moist and are essential for good eye health.
• Reflex tears: These are produced in response to irritants such as smoke, onions, or when something irritates the eye.
• Emotional tears: Triggered by emotions, these tears can contain higher levels of stress hormones and other toxins, which are excreted from the body through crying.

Function

The primary function of tears is to keep the surface of the eyes smooth and clear, and to protect the eyes from infection. Tears also play a significant role in communication and are a part of the human emotional expression system.

Production and Drainage

Tears are produced by the lacrimal glands, and they flow from the outer part of the eye toward the inner part. They drain through the lacrimal canaliculi into the lacrimal sac, then into the nasolacrimal duct, and finally into the nasal cavity.

Cultural and Psychological Aspects

Crying as a response to emotions such as sadness, joy, or frustration is a behavior observed universally among humans. It has been suggested that crying can help to relieve emotional stress and foster group bonding.

Disorders Related to Tears

Several conditions can affect tear production and function:

• Dry eye syndrome: A common condition where there are insufficient tears to lubricate and nourish the eye.
• Lacrimal gland disorders: Can lead to decreased tear production.
• Dacryocystitis: An infection of the lacrimal sac, primarily due to obstruction of the nasolacrimal duct.

See Also

• Eye
• Lacrimal apparatus
• Emotion in animals

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