Everyone we crysome more than others, and surely we have all cried at least once in our lives, whether it is for an onion cut to make a soffritto, for emotion, for a difficult condition, for dust that ended up in our eyes in a busy city or even for joy. When we cry, however, we do not realize what the chemical composition of these transparent droplets: obviously water, but also fats, proteins, enzymes and salt. But above all we do not think about the fact that our tears change composition And structure based on the reason why we cry. Let’s see together what tears are and what types of tears they exist.
What types of tears are there?
Tears can be of great three typesbased on what triggered them:
- Basal Tears: it’s always tears and constantly present in the eyewhich allow for lubrication, prevent dryness and “nourish” it, keeping it healthy. They form what is called tear filmwhich is the interface between the eye and the external environment;
- Reflected Tears: they are tears produced suddenly in response to foreign bodies that can reach the eye, for example dust, small insects, but also steam and smoke, and even too intense light.
- Emotional Tears: they are the tears most complex and are stimulated by strong emotions (of joy, stress, anger, sadness or pain). At a physiological level they are triggered by the release of hormones and of neurotransmitters (e.g. adrenaline and dopamine), which trigger mechanisms in the lacrimal glandThey are used for the tension release and the stress they suffer, and scientists are still studying their composition and triggers in depth.
What are tears made of?
As you can imagine, the largest percentage in the composition of tears is made up ofwaterfall (about 99%). The rest is sodium chloride (salt), which makes them salty, proteins and a enzyme which eliminates bacteria (the lysozyme present especially in basal tears and also in saliva). They are also present lactoferrin And fibronectinwhich have the same function as lysozyme.
The emotional tearsfurthermore, they also contain a small concentration of hormones: theenkephalin (a kind of painkiller that relieves emotional pain, but also physical pain), the prolactin (pregnancy hormone and post-orgasmic relaxation sensation), the leucine (muscle protein synthesis hormone). These hormones can help to release stress and release psychophysical tensions.
The tear film, that is the connection between the outside and the eye, as mentioned before, is composed of various layers:
- more superficially there is a layer of fat (said lipid layer). It serves to keep the eye hydrated and to prevent the tears from disappearing immediately, also making them waterproof;
- Below is the layer of water which serves to clean the eye from all impurities, lubricate the cornea and maintain it with vitamins and minerals;
- THE’last layer It is composed of proteins calls mucins. They serve to ensure that the cornea becomes hydrophilic and therefore the passage of water can be facilitated (of which the tear is mostly composed, as we were saying).
