Saturday, August 20, 2016

So Many Tears

     Our eyes are strong, yet delicate. They allow us to see, but they must be well cared for. Our bodies know this, so we're equipped with a nifty tool called tears. Tears protect our eyes from dust, kept our eyes lubricated, and help showcase our emotions, but what purpose do tears serve when we yawn, sneeze, choke, vomit, or laugh? You can choke on a sour patch kid, spit it up, then spend what feels like ten minutes wiping tears from your eyes like windshield wipers against rain. Why though? Your eyes weren't in danger when that sour patch wouldn't budge. Nor are they in danger whenever you yawn or laugh. Typically your eyes are closed for most of that journey. So why do we tend to tear up when we yawn, sneeze, choke, laugh, and yes vomit? What exactly is the point?
      Well first off, the scientific name for tearing is "lacrimation." This term comes from the lacrimal gland, which produces tears. Tears contain water, potassium, urea (yes, that urea), sodium, glucose, lysozymes, and few other bodily fluids. Produced in the lacrimal gland, tears travel across your eyes on thin layers of film to the tear ducts. Precorneal film coats your eyes and contains three layers: the lipid, aqueous, and mucous. The lipid layer contains oils and creates a hydrophobic barrier that keeps tears from spilling all over your cheeks (or tries to. Sometimes you just gotta let it spill). The aqueous layer contains water, electrolytes, and proteins, and promotes the spread of tear film. The mucous layer contains mucins, a protein, and is responsible for coating the cornea and providing an even distribution of tear film.
     Tears seem so general, but there's actually three different types: basal, psychic, and reflex. Who knew tears could be categorized? Basil tears are the tears that kept your cornea wet and clean. Reflex tears are formed when your eye is irritated. That irritation can be caused by pepper spray, onions, wind, bright light, the list goes on. Psychic tears are produced when you are heavily emotional, stressed, or are in physical pain. Stub your toe? That's psychic tears. Have to finish that 50 page paper by midnight and it's currently 9:04 PM and you're on page six? Psychic tears strike. The chemical makeup of tears also varies based on the type. 
     So we know the three types of tears that exist, but that doesn't answer the original question. Why exactly do we tear when we cry, laugh, or yawn? What's the purpose? Well it may be your reflexes. Whenever you choke, your mouth secretes fluid to help whatever's in your throat to slide free. Because of reflexes, tears are produced and travel towards your throat, but the pressure from your constant coughing pushes those tears back up into your tear duct, thus they come out of your eyes. Insane. When you yawn, you squeeze your eyes shut. The lacrimal gland is above your eye and tear ducts are on your eyelids. When you close your eyes tightly, you cut the tears off from being able to travel to the tear ducts. The punctum on your eyelid that collects tears cannot, so those tears build up on your eye. This applies (and sorry to have to keep using this word) to vomiting as well. You squeeze your eyes super hard and you tend to cough a bit afterwards.
     According to Robert Provine, a University of Maryland at Baltimore psychologist, laughing and crying are both similar. "Both laughing and crying occur during states of high emotional arousal, and don't clearly turn on and off." Other possible reasons are that your tear ducts for instance get exposed to pressure and vibrations when you vigorously laugh. There also may be evidence that the same part of the brain is responsible for both crying and laughing. Research also shows that tears can be summoned by a variety of emotional responses, not just sadness. "Angry tears."
     And my nose? Why does my like to run after a cry? Well because your nose is connected. Excess tears from your tear ducts, or your nasolacrimal duct drain into the inferior nasal meatus where you tears mix with mucus. The wateriness of tears causes your nose to run. Do you ever taste your tears? That is also why. Amazing.
     While tears are important, there is a point to producing too many. Crocodile tear syndrome, also known as Bogorad's syndrome, is a when you can't help but produce tears when you eat or smell food. Dry eye syndrome is a common disorder that stems from an abnormality in the tear film, causing the eye to not being able to produce enough tears. A variety of other issues can cause this as well, form LASIK surgery to vitamin A deficiency to age to pregnancy. This is also common in dogs. And if you want to sound scholarly, you can call dry eyes by their scientific name: keratoconjunctivitis sicca.
     Who knew tears were so complicated. They're just as complicated as our emotions that summon them. They be an annoyance whenever you just want to have a laugh or yawn, but at least you know they don't do it to be annoying - it's reflexes. It's emotion. It's just that they wan't to see the world. (Get it?).
     Fun fact about onions: according to, the reason they are so bad at this is because when you cut them they release propanethial sulfoxide. This gas mixes with your tears and creates a mild does of sulfuric acid. And that stings. It's a defense mechanism. Who knew onions were so defensive?

*Sources: LasikMD, Naked Scientists, Wikipedia, Today I Found Out, and Prevention.

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