chemical composition tears varies depending cry

Human body

Published on October 18th, 2013


The chemical composition of tears varies depending on why we cry

Have you ever wondered why humans cry when they feel a strong emotion , while other members of the animal kingdom will not shed a tear?

People have tear ducts to lubricate and protect the eye from dust and other particles. Ducts are under the eyelids and produce a salty liquid - tear - which spreads over the eye after each blink. Animals also have the ability to produce tears, but not necessarily for the same reason as people.


The human eye generates three types of tears :

  •     basal tears that protect the eye and keep it moist
  •     reflex tears witch clean the eye when its irritated (for example, when we cut an onion)
  •     emotional tears flow in response to sadness, suffering or physical pain

Interestingly, the composition of tears varies depending on the reason for crying . Studies conducted by researchers have shown that emotional tears contain more manganese, substances that affects the temper, and more prolactin, a hormone which controls the production of milk. Specialists believe that the crying out manganese and prolactin helps to release tension balancing stress levels in the body and eliminating chemicals accumulated, allowing the person crying to feel better.

Beyond this minor psychological benefit, the most likely reason why we produce emotional tears is that they are a means of communication. Babies can’t speak. The only way that babies can communicate frustration, pain, fear is by crying. Adults may use crying to form links with others. Expressing sadness may encourage those around us to support us and reassure us. Ways in witch crying is culturally accepted are at funerals and weddings, this can bring people closer to each other.

Although there is a debate between scientists: “do animals have emotions and can they express them ?”. Some animals seem indeed to cry for emotional reasons. Elephants seem to cry when a family member dies, guarding his body and traveling great distances to see it. Elephant experts from London Zoo once told Charles Darwin that animals cry for their dead relatives. Chimpanzees mourn their deceased, but some scientists insist that it’s just tears aimed at cleaning the eye.

Source: ScienceLine

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chemical composition tears varies depending cry 1

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