113 liters of tears per year, 'rich people' cry more

Tears are an indispensable part of every human body, and at the same time a highlight in the picture of human emotions.

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

Although familiar, there are certainly many things we do not know about these interesting water drops.

113 liters per year

Crying is a mechanism of tear secretion from the corner of the eye controlled by the brain or as a natural reaction to external stimuli. Tears are also a solution used to clean dirt stuck in the pupil, caused by dust flying into the eye, dirty water coming into contact with the eye, and tear gas drying the eye.

The lacrimal glands are the body's "tear factories," located above and below each eye in the eye cavity. The lacrimal glands are flat, round, pea-sized glands that drain tears into the eye, keeping the cornea and conjunctiva moist.

Tears are produced in large quantities, about 300ml per day, an average of about 113 liters per year. When sleeping, the lacrimal glands almost stop working.

Many kinds of tears

The structure of the tear film is made up of basal tears. Photo: hoopesvision.com

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

Specifically, basal tears create a 3-layer "tear film": right next to the pupil is a mucus layer that helps the film adhere to the cornea, next is a water layer that keeps the pupil wet and removes harmful bacteria, protecting the cornea from damage, and the outermost layer is a lipid layer that helps keep the surface smooth so people can see through and prevent the inner layers from evaporating.

"When the eyes are affected by wind, dust, or insects, reflex tears will be produced to protect the eyes," said Dr. Michael Roizen, USA.

Finally, tears to release emotions appear when people have strong emotions, especially when 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, the adult body has 250g of salt and plays an important role in maintaining the balance of the body's internal fluid environment. This environment is responsible for transporting food and oxygen to all organs.

Tears also contain salt, with less than 6 grams of salt in one liter of tears. This amount of salt is obtained from blood, which contains 9 grams of salt in one liter of blood. Tears contain salt, so they also help limit the growth of bacteria in the eyes, in addition to keeping the eyes moist and not dry.

Why yawn and laugh tears?

According to the American Academy of Ophthalmology, the human body is unique in that tears have both a producer and a consumer. In the inner corner of each eye, there are small holes that collect tears, which flow down to the nose, where they mix with mucus and flow out. This is also one of the reasons why our noses start to run when we cry.

In addition, when we yawn, laugh too much, sneeze, cough, or vomit, we can all have tears. The reason is that when performing these actions, a pressure is created in the mouth that affects the nasal cavity, temporarily blocking the drainage of tears. Therefore, tears cannot go down the nose, so they overflow into the eyes and are forced to escape.

Why do women cry more than men?

In countries with a culture of free expression, men cry more. Photo: Maud Fernhout

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

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

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

However, crying more or less is not a natural process. A study of 35 countries found that the frequency of crying between men and women varies from country to country.

Specifically, according to a 2011 global cultural study, the crying level is balanced between men and women in countries where people tend to freely express their emotions such as Chile, Sweden, or the US... On the contrary, in Ghana, Nigeria or Nepal... the crying level in women is quite different from that of men.

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

On the contrary, poor countries that should cry more do not, because cultural norms in these countries are quite "strict" about crying, especially in men.

According to TTO