How are tears produced?

Answer 1

G'day Tan,

Thanks for your question.

Tears are a liquid produced by the body's process of lacrimation to clean and lubricate the eyes. The word lacrimation may also be used in a medical or literary sense to refer to crying.

In humans, the tear film coating the eye has three distinct layers:

1. The mucous layer contains mucin secreted by the conjunctival goblet cells. The inner-most layer of the tear film, it coats the cornea to provide a hydrophobic layer that allows for even distribution of the aqueous layer.
2. The aqueous layer contains water and other substances such as proteins (e.g. tear lipocalin, lactoferrin and lysozyme) secreted by the glands of Kraus and Wolfring and the lacrimal gland.
3. The lipid layer contains oils secreted by the Meibomian glands. The outer-most layer of the tear film, it coats the aqueous layer to provide a hydrophobic barrier that retards evaporation.

There are three basic types of tears:

1. Basal tears: In healthy mammalian eyes, the cornea is continually kept wet and nourished by basal tears. They lubricate the eye and help to keep it clear of dust. Tear fluid contains water, mucin, lipids, lysozyme, lactoferrin, lipocalin, lacritin, immunoglobulins, glucose, urea, sodium, and potassium. Some of the substances in lacrimal fluid fight against bacterial infection as a part of the immune system.
2. Reflex tears: The second type of tears results from irritation to the eye by foreign particles, or substances such as onion vapors or tear gas or pepper spray. These reflex tears attempt to wash out irritants that may have come into contact with the eye.
3. Crying or weeping: The third category, generally referred to as crying or weeping, is increased lacrimation due to strong emotional stress or physical pain. This practice is not restricted to negative emotions; many people have been known to cry when extremely happy. In humans, emotional tears can be accompanied by reddening of the face and sobbing — cough-like, convulsive breathing, sometimes involving spasms of the whole upper body. Tears brought about by emotions have a different chemical make up than those for lubrication.

One lacrimal gland is located above and beside each eye, behind the upper eyelid. The lacrimal glands secrete lacrimal fluid which flows through lacrimal ducts into the space between the eyeball and lids. When the eyes blink the lacrimal fluid is spread across the surface of the eye. Lacrimal fluid gathers in the lacrimal lake, then flows via the puncta through the lacrimal canaliculi at the inner corner of the eyelids through the nasolacrimal duct, and finally into the nasal cavity. An excess of tears, as with strong emotion, can thus cause the nose to run.

I enclose sources for additional reference.

Regards

Answer 2

To put it in a concise but yet scientifically correct manner-

"production" of tears involves 1- production 2-secretion
this process is called Lacrimation

Tears are produced in lacrimal glands which are just outer to the eyes. They keep on producing tears all the time.
Whenever there is a stimulus for release of theses tears (like grief, dust or even onions which release Sulfur Allyl Sulfide) the appropriate nerves carry it to these glands which release these tears.

Answer 3

tears r produced by a gland named aqueus humur present in our eye.
tears r produced when u cry or when the atmospheric air irritates ur eye, then the muscle in our eye contracts n due to this reason tears r produced.
hope this will do.

Answer 4

tears r produced by the lacrimal glands beneath the eye lids

Answer 5

there is a gland similar to the one that produces sweat that gets stimulated . this gland is located near the orbiculatis otis and maintains the eye lubricated through the tear ducts that's located in the inner canthus.

Answer 6

All you ever wanted to know about tears:

Answer 7

when instructed by the brain the lacrimal glands produce tears
please rate my answer the best

Answer 8

From a chemical substance present in our eyes: Aqueous Humor

Answer 9

by the tear glands, when they are stimulated.

Answer 10

Right after you get kicked in the nuts