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Daemon
Posted: Monday, September 04, 2017 12:00:00 AM
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Tears

Human beings produce three basic types of tears: basal tears, which lubricate the eye to keep it clear of dust; reflex tears, which wash out irritants, like onion vapors, that come into contact with the eye; and psychic tears, which result from strong emotions or physical pain and have a different chemical makeup than those created for lubrication. Though tearing as an emotional reaction is considered by many to be a uniquely human phenomenon, some studies suggest that what animals cry too? More...
KSPavan
Posted: Monday, September 04, 2017 12:37:33 AM

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Article of the Day
Tears
Human beings produce three basic types of tears: basal tears, which lubricate the eye to keep it clear of dust; reflex tears, which wash out irritants, like onion vapors, that come into contact with the eye; and psychic tears, which result from strong emotions or physical pain and have a different chemical makeup than those created for lubrication.
KSPavan
Posted: Monday, September 04, 2017 12:37:34 AM

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Location: Kolkata, Bengal, India
Article of the Day
Tears
Human beings produce three basic types of tears: basal tears, which lubricate the eye to keep it clear of dust; reflex tears, which wash out irritants, like onion vapors, that come into contact with the eye; and psychic tears, which result from strong emotions or physical pain and have a different chemical makeup than those created for lubrication.
taurine
Posted: Monday, September 04, 2017 4:01:26 AM

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I heard also Tears for Fears... Boo hoo!
ChristopherJohnson
Posted: Monday, September 04, 2017 7:19:33 AM

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I did not know these types of tears had different origin.
monamagda
Posted: Monday, September 04, 2017 7:38:42 AM

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Why are humans the only animals that cry?


Pet owners often claim their dogs cry. Darwin thought monkeys and elephants wept. But modern scientists believe the only animal to really break down in tears is us. So why do we do it, and why do we change the way we cry as we grow older?



Charles Darwin thought that tears had no modern adaptive function.

A similar view was expressed in poetry by Tennyson when he wrote, 'Tears, idle tears, I know not what they mean'.

Professor Ad Vingerhoets from Tilburg University in the Netherlands has written extensively about our capacity to burst into tears, including his book Why Only Humans Weep: Unravelling the Mysteries of Tears.

'In the sense of producing emotional tears, we are the only species,’ he says. All mammals make distress calls, like when an offspring is separated from its mother, but only humans cry, he says.


http://www.abc.net.au/radionational/programs/bodysphere/features/4837824

raghd muhi al-deen
Posted: Monday, September 04, 2017 7:55:37 AM

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Tears
Also found in: Dictionary, Thesaurus, Medical, Legal, Acronyms, Idioms, Encyclopedia.
Related to Tears: crocodile tears
For other uses, see Tear (disambiguation).
Anatomy of lacrimation, showing
a) Lacrimal gland
b) Superior lacrimal punctum
c) Superior lacrimal canal
d) Lacrimal sac
e) Inferior lacrimal punctum
f) Inferior lacrimal canal
g) Nasolacrimal canal

Tearing (/ˈtiərɪŋ/), lacrimation, or lachrymation (from Latin lacrima, meaning 'tear') is the secretion of tears, which often serves to clean and lubricate the eyes in response to an irritation of the eyes.[1] Tears formed through crying are associated with strong internal emotions, such as sorrow, elation, love, awe and pleasure. Laughing or yawning may also lead to the production of tears.

Physiology

In humans, the tear film coating the eye, known as the precorneal film, has three distinct layers, from the most outer surface:[2]
Name Container(s) Secretors Functions
Lipid layer Oils Meibomian glands (or tarsal glands) Coats the aqueous layer, provides a hydrophobic barrier that envelops tears and prevents their spilling onto the cheek. These glands are found among the tarsal plates. Thus, the tear fluid deposits between the eye proper and oil barriers of the lids.[3]
Aqueous layer Electrolytes, 60 metabolites—Amino Acids (1-Methylhistidine/3-Methylhistidine, Arginine, Asymmetric, Asymmetric dimethylarginine/Symmetric dimethylarginine, Citrulline, Creatine, Glutamine, Homoarginine, Hydroxyproline, Phenylalamine, Proline, Pyroglutamic acid, Serine, Taurine, Theonine, Tryptophan, Tyrosine, Urocanic acid, Valme), Amino Alcohols (Panthenoll); Amino Ketones (Allantoin, Creatine), Aromatic Acids (Cinnamic acid, o-Coumaric acid/m-Coumaric acid/p-Coumaric acid), Carbohydrates (N-Acetylneuraminic acid), Carnitines (Acetylcarnitine, Carnitine, hexanoylcarnitine, Palmitoylcarnitine); Cyclic Amines (Niacinamide); Dicarboxylic Acids (Fumaric acid/ Maleic acid), Nucleosides (1-Methyladenosine, Adenoisine, Cytidine, Guanosine, Inosine, S-Adenosyl-homocysteine, S-Adenosyl-methionine, Uridine, and Xamthosine), Nucleotides (ADP, AMO, CMP, Cytidine diphosphate choline, GMP, IMP, UDP, UMP, UDP-N-acetylgalactosamine/UDP-N-acetylglucosamine), Peptides (Oxidized glutathione), Phospholipids (1-Palmitoyl-lysophosphatidylcholime), Purines and derivatives (Hypoxanthine, Theobromine, Uric acid, Xanthine), Purines and derivatives (4-Pyridoxic acid), Quaternary Amines (Acetylcholine, Glycerolphosphocholine, Phosphocholine), and Tricarboxylic Acids (Citric acid)--and other substances such as proteins (e.g., antibodies,[2] lipocalin, lactoferrin, lysozyme,[4] and lacritin) Lacrimal gland Promotes spreading of the tear film, the control of infectious agents and osmotic regulation.
Mucous layer Mucins Conjunctival goblet cells Coats the cornea, provides a hydrophilic layer and allows for even distribution of the tear film.

Having a thin tear film may prevent one's ability to wear contact lenses, as the amount of oxygen needed is higher than normal, and contact lenses stop oxygen from entering the eye. Eyes with thin tear film will dry out while wearing contact lenses. Special eye drops are available for contact lens wearers. Certain types of contact lenses are designed to let more oxygen through to the eye.
Drainage of tear film

The lacrimal glands secrete lacrimal fluid, which flows through the main excretory 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, and is drawn into the puncta by capillary action, then flows through the lacrimal canaliculi at the inner corner of the eyelids entering the lacrimal sac,[3] then on to the nasolacrimal duct, and finally into the nasal cavity. An excess of tears, as with strong emotion, can thus cause the nose to run. [1]
Types

There are three very basic types of tears:[1]
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with my pleasure
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