Richa Patel emailed us to ask "What makes tears?" We put our
investigating hat on and set off to find out...
Eyes are amazing things, so we need to protect them. You make
tears every time you blink. When you blink, the tears spread out in
a thin film over your eyeballs. Tears are made in tear glands on
your upper eyelids. The tears flow into your eyes through tiny tear
ducts and help to keep your eyes free things that could irritate
them, like dust. Even if you're asleep, tears are still being
produced! Your tears have a tiny bit of salt in them, which is
antiseptic and helps to prevent eye infections. Used tears go down
two tiny holes in your upper and lower eyelids to the back of your
nose, where they are swallowed or blown out with your snot!
If something gets in your eye and irritates it, your tear glands
make more tears to try and flush the irritant away. These are
reflex tears. If something makes you sad or extra
happy, your tear glands produce emotional tears.
If you produce lots of tears, they can't all drain into your nasal
cavity, so they overflow and run down your cheeks.
What if you cry whilst you're chopping onions? Planet Science
explains it all here!