Why Do We Cry?
In a Nutshell : Crying is beneficial to health and mental well-being. A good cry is great for body and mind.
The Longer Answer is …
While we, and most animals, have a system to keep our eyes moist – it’s only humans that cry emotional tears, which are triggered by a part of the brain that’s responsible for feelings of sadness. This melancholy then sends signals to the endocrine system to release hormones around our eyes that cause tears.
In addition to emotional tears, there are tears caused by irritation. If we get something in our eyes, such as a piece of dust or debris, producing tears helps wash it out of the eye.
Tear Plumbing …
The tear glands, or lachrymal glands, are located under the upper eyelid. Tears flow through tiny ducts that secrete tears onto the eyeball in a process called lacrimation.
The tears form a film that coats the eye with three distinct layers…
- The innermost layer, which covers the eyeball, is made of a protein called mucin. This layer, secreted by the conjunctiva, coats the cornea and permits an even distribution of the next layer…
- The Middle layer is the aqueous layer, made of water and proteins.
- The outermost layer contains oils that prevent evaporation of the other layers.
Every time a person blinks, the tear film is spread over the eye to keep it moist and free of dust and other irritants.
Afterwards, tears drain into two tiny openings on the edges of the upper and lower eyelids at the inner corner of the eye. From there, they are channelled by the tear ducts into the nasal cavity, which drains into the throat, and then swallowed.
If there are too many tears, they overflow the lower lid and run down the cheek.
Whilst tears have the job of protecting our eyes, they also work hard in other surprisingly quite complex ways. In addition to keeping our eyes from drying out, tears have a bit of salt in them, which helps prevent infection. They even carry oxygen and some nutrients to the eye’s surface. If something gets in one of our eyes and irritates it, the tear glands flood our eyes with tears and try to flush away the invader.
Tear production goes on even when we are sleeping.
So, all in all a rather marvellous lubricating plumbing system – helping to keep one of the most precious of our senses, sight, working correctly and efficiently.