![](https://imgur.com/qxndAUr.jpg)

*[Picture](http://www.sheknows.com/health-and-wellness/articles/1105697/types-of-tears-and-their-benefits)*

Tears are a very interesting phenomenon in a human’s body because not all tears are the same. Did you know that? But let me be consecutive and at first start with anatomic nuances.

Above the eye there is a special gland located that produces tears. It is called lacrimal gland. Tears emerge here and then due to small channels (ducts) they travel to the eye. Actually, the glands work all the time to create tears to moist the eye, and only when there is more than enough quantity of them tears start to run out from the eye. This happens because drain system does not already cope meaning that lacrimal sac is already full.

Look at the picture for better understanding of the mechanism.

![](https://imgur.com/0wFwVQ8.jpg)

*[Picture](http://www.ajnr.org/content/37/11/2134.figures-only)*

It might be very curious to say that not all tears are the same. Scientists define three types of them.

1. Basal tears.
They keep our eyes healthy and moisty. Every time we blink, the eyes get wet and provided with needed conditions. 
As for the chemical structure of basal tears they are comprised mostly of salts (sodium chloride and potassium chloride), water and a bit of mucus which protects the cornea of the eye. The quantity produced each day equals to about 1,2 ml. The drainage occurs through the nasal cavity.
When we sleep the function of basal tears stops and renews again after waking up.

2. Reflex tears.
They can be also called protective tears because are formed in the situations when the eye is «attacked» by any irritant such as smoke, dusty wind, small objects. Sensory nerves of the cornea get the information about some kind of irritation, so the body takes defensive measures. When we cry while cutting an onion it means our body exports reflex tears as well. 
The structure is very similar to basal tears, just with one difference that reflex tears possess more antibodies (Immunoglobulin A) to be able to win microbes and other chemicals.

3. Emotional tears.
Logical that these tears are triggered by some emotions, both positive (happiness, excitement, laughter) and negative (anger, sadness). The part of the brain responsible for this is hypothalamus. It releases neurotransmitters known as acetylcholine which stimulate tears.
The structural peculiarity of these tears is presence of proteins, i.e. hormones. It means that stress hormones go out together with tears, causing feeling of relief and ease. This feature is very useful for the body because if the level of stress hormones is high the body becomes toxic, its immune system weakens and there is a probability to get some disease.

And now I would like to write about one photographic observation. Rose-Lynn Fisher (photographer) accomplished a project called «Topography of Tears». It is an amazing idea of taking pictures of dried tears caused by different reasons. Have a look at how visually various tears are.
Dried tears are at the utmost crystallized salt. It is true that chemically all the tears shown below are the same, but what makes them look differently these are circumstances of crying.

Tears of change:

![](https://imgur.com/ZXES5lq.jpg)
*[Picture](https://www.smithsonianmag.com/science-nature/the-microscopic-structures-of-dried-human-tears-180947766/)*

Onion tears:

![](https://imgur.com/S0EZOIu.jpg)

*[Picture](https://www.smithsonianmag.com/science-nature/the-microscopic-structures-of-dried-human-tears-180947766/)* 

Tears of grief:

![](https://imgur.com/TFog7pX.jpg)

*[Picture](https://www.smithsonianmag.com/science-nature/the-microscopic-structures-of-dried-human-tears-180947766/)*

Tears of laughter:

![](https://imgur.com/nHAIqSb.jpg)

*[Picture](https://www.smithsonianmag.com/science-nature/the-microscopic-structures-of-dried-human-tears-180947766/)*

Next time you wanna cry, just cry. Let all stress hormones rush out from your body and then I am sure feeling of slight happiness will overwhelm you. 
Be healthy.

Sources: [1](http://sciencewows.ie/blog/tears-come-cry/), [2](https://www.huffingtonpost.com/2014/01/10/tear-facts_n_4570879.html), [3](https://www.smithsonianmag.com/science-nature/the-microscopic-structures-of-dried-human-tears-180947766/), [4](http://www.chemistryislife.com/the-chemistry-of-tears).