With 113 liters of tears shed each year, the 'rich' cry more.

Tears are an integral part of the human body and a highlight in the tapestry of human emotions.

Tears play an important role in everyone's life. Photo: Getty Images

Despite their familiarity, there's certainly much we don't know about these fascinating water droplets.

113 liters per year

Crying is a mechanism of tear secretion from the corners of the eyes, controlled by the brain or as a natural reaction to external stimuli. Tears also serve as a solution to clean away dirt and debris from the pupils, such as dust entering the eyes, dirty water contact with the eyes, or irritating fumes that dry out the eyes.

The lacrimal glands are the body's "tear factories," located above and below each eye in the eye socket. These small, flattened, pea-sized glands are circular in shape and have a system that drains tears into the eye, keeping the cornea and conjunctiva moist at all times.

Tears are produced in large quantities, about 300ml per day, averaging about 113 liters per year. During sleep, the tear glands almost completely cease functioning.

Many types of tears

The structure of the tear film is created by the presence of background tears. Image: hoopesvision.com

Tears come in many forms, but can be divided into three main types based on their function: basal tears, reflex tears, and emotional tears.

Specifically, basal tears form a three-layered "tear film": right next to the pupil is a mucous layer that helps the film adhere tightly to the cornea; next is a watery layer that keeps the pupil constantly wet and removes harmful bacteria, protecting the cornea from damage; and the outermost layer is lipid, which keeps the surface smooth, allowing for clear vision and preventing the inner layers from evaporating.

"When the eyes are affected by wind, dust, or insects, reflex tears are produced to protect the eyes," said Dr. Michael Roizen from the United States.

Finally, tears are a way to release emotions when people experience intense feelings, especially when they are sad.

"Tears can stimulate the release of brain chemicals such as the hormone oxytocin and endogenous opioids that help us feel relaxed and relieved after crying," said Vingerhoets, a professor at Tilburg University in the Netherlands and an expert in tear research.

Why are tears salty?

Salt is present in every cell in the body. Specifically, an adult's body contains 250g of salt, which plays a crucial role in maintaining the balance of fluids within the body. This balance is responsible for transporting food and oxygen to all organs.

Tears also contain salt; one liter of tears contains less than 6g of salt. This salt is obtained from blood, as one liter of blood contains 9g of salt. Because tears contain salt, they also help limit the growth of bacteria in the eyes, in addition to keeping the eyes moist and preventing dryness and irritation.

Why do we cry when we yawn or laugh?

According to the American Academy of Ophthalmology, the human body is unique in that tears have both a production and consumption mechanism. In the inner corner of each eye are tiny pores that collect tears, which then drain into the nose, mixing with nasal mucus before flowing out. This is also one reason why our noses run when we cry.

Additionally, when yawning, laughing excessively, sneezing, coughing, or vomiting, we can all experience tears. This is because these actions create pressure in the mouth that affects the nasal cavity, temporarily blocking the tear drainage pathway. Therefore, tears cannot flow down the nose and instead back into the eyes, forcing them to exit.

Why do women cry more than men?

In countries with cultures that allow for free expression of emotions, men cry more often. Photo: Maud Fernhout

In the 1980s, biochemist William H. Frey found that women cried an average of about 5.3 times a month, while men cried an average of about 1.3 times a month.

More than 30 years later, these numbers have remained virtually unchanged based on recent studies, the most notable of which is the work of Lauren Bylsma from the University of Pittsburgh, USA, in 2011.

Biologically, the reason women cry more than men is that the hormone testosterone, which is more abundant in men, may have an effect on limiting the urge to cry, while the hormone prolactin, which is more abundant in women, seems to promote this phenomenon.

However, crying more or less is not necessarily a natural process. A study of 35 countries showed that the frequency of crying varied between men and women across countries.

Specifically, according to a 2011 global cultural study, the level of crying is balanced between men and women in countries where people tend to freely express their emotions, such as Chile, Sweden, or the United States. Conversely, in Ghana, Nigeria, or Nepal, the level of crying among women differs significantly from that of men.

At the same time, people in wealthy countries tend to cry more. This may sound a bit paradoxical, but it's because they live in a cultural environment that allows them to cry naturally.

Conversely, poorer countries, where people should ideally cry more, don't, because cultural norms in these nations are quite "strict" about crying, especially for men.

According to TTO