Why do we cry? The three types of tears - Alex Gendler
View full lesson: http://ed.ted.com/lessons/why-do-we-cry-the-three-types-of-tears-alex-gendler Whether we cry during a sad movie, while chopping onions, or completely involuntarily, our eyes...
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Our story is about a girl named Iris. Iris is very sensitive. (Bird cawing) So much that she is always in tears. She cries when she's sad, when she's happy, (Godzilla roars) and even tears up when things just get to her. She has special lacrimal glands to make new tears and special tubes, called lacrimal puncta, to drain old ones away. And she cries so much that she goes through ten ounces of tears per day, thirty gallons a year! In fact, if you look closely, you'll see that she's crying a little bit all the time. The basal tears that Iris constantly produces form a thin coating of three layers that cover her and keep dirt and debris away. Right next to Iris is the mucus layer, which keeps the whole thing fastened to her. On top...
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Our story is about a girl named Iris. Iris is very sensitive. (Bird cawing) So much that she is always in tears. She cries when she's sad, when she's happy, (Godzilla roars) and even tears up when things just get to her. She has special lacrimal glands to make new tears and special tubes, called lacrimal puncta, to drain old ones away. And she cries so much that she goes through ten ounces of tears per day, thirty gallons a year! In fact, if you look closely, you'll see that she's crying a little bit all the time. The basal tears that Iris constantly produces form a thin coating of three layers that cover her and keep dirt and debris away. Right next to Iris is the mucus layer, which keeps the whole thing fastened to her. On top...
