Tears are important for the health of our eyes! They are not a waste product, like urine. Special ducts containing cell types that secrete oils, water, and mucus produce tears. Interestingly, there are three different tear-types: Basal tears are continually produced and keep our eyes wet, nourished, and clear from dust. They also have antibacterial properties. Reflex tears result from eye irritants like foreign particles or onion vapor. (I just ate sushi for lunch with wasabi and my reflex tears were stimulated!) The third type of tears are crying or weeping tears that are produced from strong emotions (positive or negative) and physical pain. Crying tears, unlike the other tear-types, contain hormones.

Tears contain a lot of things, including some wastes, but they are more important for protecting our eyes.

Tears are very important. They wash dirt out of our eyes. They help to kill germs. They keep our eyes wet.

Our eyes make tears all of the time, but they make more when we cry or when there is stuff on them. When the light is bright, they also make more tears.

Our eyebrows and eyelashes also protect our eyes. How do they do that?

Keep asking questions, that’s what scientists do.

Nope! although that is a very good idea. They are mostly used to clean the eyes. Crying from being sad is a secondary use and it's a very complicated thing. It's partly a social thing, as in a sad person crying tells people around them that they are sad. It may happen because of connections in the brain related to tears being close to emotional centers. It's not a very well-understood event, but that just means there is more out there to discover!

So that really depends on what you mean by waste product. Tears have a function so they aren’t really waste like urine for instance. They can contain waste like when you get something in your eye and the tears help remove it. But they also serve normal functions like keeping your eye wet and fighting against bacteria. When people are unhappy and cry, those tears are actually a little different than normal tears. Crying tears contain chemicals that actually make you feel better.

Not really. Tears remove bad things that get into your eyes. They're really more of a cleaning fluid.