Freshly Baked Science
Why Do We Cry?
23rd January 2019
Tears are a strange phenomena. They aren’t always a reflection of our emotions and scientists still don’t fully understand them. But first, let’s explore what we know so far.
Tears are made mostly from water. They have a little bit of salt, oil, and mucus too. The oil is important because they stop the tears from running out of our eyes or the water from evaporating. Mucus helps the tears stay close to the eyeball, rather than running out. They may also have enzymes, for killing bacteria, or hormones which change the way we feel.
That gives a good idea of the components, but where do they come from? They’re made from the tiny glands above our eyes and travel down to the eyes through ducts, like a pipe system. On a normal day, the ducts are constantly providing moisture to our eyes and we don’t even notice it. They even return through a separate set of ducts, and the cycle continues.
The tears that you will be most familiar with are those that come when we cry. We can cry because of our emotions but we also produce tears when our eyes are irritated. A good example of irritation is cutting onions, or even from dirt or dust particles.
Aside from the reason for crying, the mechanism is the same. We cry because there are too many tears being produced and the cycle can’t keep up. When the duct system can’t clear the moisture in time, the tears overflow. Have you noticed that you can also get a runny nose when you’re crying? It’s because the drainage system goes through our nose too. Those are all the extra tears!
That’s what we know so far, but why do we cry? You might be surprised to know that scientists aren’t yet sure about why we cry when we’re emotional. They do, however, understand that the tears from happiness and sadness are different from the tears that we produce to keep our eyes clear each day. Although we may not know the reason behind emotional crying, we do know that there are different types of tears. This means that the tears have a different composition based on how we’re feeling.
The regular tears that pass through the eye each day are called basal tears. These are the ones containing water, salt, oil and mucus, that we talked about earlier. When our eye is irritated, like when we cut onions, we produce irritant tears. Both irritant and basal tears have the same elements but also the same goal. They need to protect the eye from harmful bacteria. The only difference in irritant tears is that since they’re triggered by an external stimulus, they produce more tears and more quickly.
The last type of tears are emotional tears because they form when we’re happy or sad. These tears don’t have a purpose in protecting the eye and they’re slightly different in composition. Emotional tears have more proteins. These proteins help with stress, which is why we usually feel better after we cry.
In fact, next time you’re holding back your tears, it might be better to let them flow. It’ll release the stress and help you feel better, even if it makes you feel a little embarrassed. Just remember, there’s nothing wrong with crying. Each type of tear has a purpose.