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Asked by to Andrew, Elaine, Emma, Michael, Nancy on 17 Jun 2014. This question was also asked by phoebetomaz.
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Nancy Carlisle answered on 17 Jun 2014:
Tears come from our tear ducts, and are normally produced to lubricate our eyes. When we blink the tear fluid gets moved over the whole eye. I don’t know why we secrete more of this fluid when we cry?! Anyone else know?
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Emma Reid answered on 17 Jun 2014:
As far as I know humans are the only species who cry tears due to emotional state. The tear fluid we secrete when we cry is very different from standard tear fluid, as it contains more hormones. The fifth cranial nerve carry impulses related to “normal” tears but when this nerve is cut, it doesn’t have any effect on emotional tears! It’s a very strange phenomenon which isn’t well understood! 🙂
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Michael Kelly answered on 18 Jun 2014:
Tear come from the lacrimal gland, which is under the upper outer eye of the eye socket. Have a look here, http://en.wikipedia.org/wiki/Lacrimal_gland
Here’s a paper on emotional tears http://www.ncbi.nlm.nih.gov/pubmed/19568753, I remember reading that emotional tears contain molecules called prostaglandins, these change the state of the small blood vessels and the inflammatory state on the surface of the eye
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Comments
jasminebvbarmy commented on :
oh ok but where are our tear ducts?
Michael commented on :
The ones that feed onto the eye are in the upper fornix, under the upper eyelid. The drainage is through two small holes in your eyelids near your nose called the canaliculi, these drain into the back of your nose. Thsi is why in part you get a runny nose when you cry.
phoebetomaz commented on :
That’s so cool
jasminebvbarmy commented on :
thank you that’s so interesting!