Understanding Tears

woman crying

We produce tears for many reasons. Our eyes may be brimming with tears when we cut up an onion, suffer from seasonal allergies, or when foreign objects irritate our eyes. We may also shed tears when we get too emotional or when we feel extreme pain. In many cases, yawning and urinating can also make us cry.

3 types of tears

Tears are categorized as basal, reflex, and emotional. All of these types occur for different reasons. We release basal tears regularly to keep our eyes lubricated. Basal tears contain water, mucin, lysozyme, lipids, lipocalin, lactoferrin, immunoglobulins, lacritin, urea, glucose, potassium, and sodium.

There are also the reflex tears, which we produce when our eyes get irritated. These tears have the same chemical make up as basal tears. Lastly, we produce emotional tears when we feel strong emotions such as anger, sadness, and even laughter. We also tend to produce tears due to physical pain.

Many researchers suggest that our body can’t differentiate between physical and emotional pain, even if our mind can. Compared with basal and reflex tears, emotional tears contain more prolactin (a protein-based hormone), leucine enkephalin (a natural painkiller), and adrenocorticotropic hormone.

Physiology

The tear film that coats the human eye has three different layers. The lipid layer is the outermost layer, which contains oils produced by meibomian glands. This layer coats the aqueous layer to prevent evaporation and tears gushing onto your cheek.

The aqueous layer is the middle layer, ehich contains water and substances like proteins (for example, tear lipocalin, lacritin, lysozyme, and lactoferrin) produced by the lacrimal gland. This layer serves to spread the tear film, control infectious agents, and regulate osmosis.

The mucous layer is the tear film’s innermost layer, which contains mucin produced by conjunctival goblet cells. This layer coats the cornea and provides a hydrophilic layer, allowing for even distribution of the film.

What causes emotial tears?

According to William Frey, a biochemist and director of the Dry Eye and Tear Research Center in Minneapolis, human tears contain the stress hormone ACTH. He suggested that shedding tears helps our body reduce extra ACTH amounts and maybe other substances that accumulate after a stressful event.

Frey also suggested that emotional crying is one way to purge waste products from our body, similar to excretory processes like sweating, urinating, exhaling, and defecating. He concluded that "we may increase our susceptibility to a variety of physical and psychological problems when we suppress our tears."

Diseases and disorders

There are a number of disorders and diseases associated with tears. There’s the Crocodile Tears Syndrome, which causes patients to shed tears while eating and the Leamy Eye condition whereby the sufferer experiences excessive watering of his or her one eye, for no apparent reason. Also, the instability of the tear film can affect one’s quality of vision.

Dry eye, also known as keratoconjunctivitis sicca, is a common deficiency of the tear film. While the disorder is named "dry eye", patients can experience excessive watering of the eyes. This is a response to irritation as a result of the original tear film deficiency.

 

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