Strange and Wonderful Truths about Tears
A tearful goodbye. The tears of a clown. Breaking down in tears. The drops of liquid that fall from our eyes are ripe for metaphor, evoking emotion as much as they express it. Perhaps that’s what differentiates them from what comes out of our other face holes. They don’t merely exist for biological function. They also mean something. Whether it’s sadness or joy, tears are a physical representation of our humanity. They show our vulnerability as well as our strength. And while their function is as clear as their composition, there are a lot of things about tears that will surprise you.
Unlike what comes out of our ears and noses, there is no fancy term for tears. The Latin term for tear is lacrimālis, what your tearing system is called. Tears are made in the lacrimal gland, which is located under your eyebrow in the upper, outer area above your eye. Your lacrimal gland releases tears across your eyeball, which then collect in the inside of your eye, near your nose. From there, they move into your lacrimal sac and drain into your nose down a tube called the nasolacrimal duct. (This is why your nose runs when you cry.) When the system is flooded (from crying) or if that tube gets blocked (from swelling in your nose), your tears overflow and fall down your face.
Not all tears are the same. We make three kinds: basal, irritant, and emotional. Each has a different composition and function.
Basal tears are the ones that protect your cornea and moisten your eyes. They are made of fats, electrolytes, enzymes, proteins, and water and they coat your eyeball in three layers. The mucus layer sits closest to your eye, covered by the watery layer, topped by the oily layer. Our tears also contain lysozymes, proteins that fight off bacteria and viruses. You are constantly producing basal tears, even though you don’t know it. So are nearly all animals. Basal tears even provide a yummy food source for certain flies. Some bees literally drink human tears; something to consider if you live in…