Cameron W., 2012

Why Humans Blink


Parts of Your Eye
Humans need to blink because your eyes need to refresh themselves—which they do by blinking. Your eyes blink so things like dirt and dust don’t get in your eyes. Blinking helps your eyes not dry out or irritate. Your eyelashes keep out dust. When you blink, it makes your eyes feel good. Your eyelashes block dirt, dust, and water from getting into your eyes, though some manages to get through. Not only do your eyelashes block dirt dust and other unwanted things, but your eyebrows do too, which block out water. Your corneas use the eye lashes and the eye brows as protection (See Figure Two). Did you know that blinking is an automatic reflex, you don’t have to think about blinking, and you blink to prevent unwanted things getting into your eye?


Blinking
Eye & Eyebrows.jpg
Figure 1- The Human Eye: The Lashes and Brows help block dirt, dust, and other unwanted things.

The eye is very important. Blinking is the first line of defense, the thick lashes try to block out “bad stuff” from irritating your eye. Then, if things fast-coming or just manage to get through, you close your eyes and try to block your face by using your arms. After blinking, water is the eye’s next defense. Our eyes also block out things like flying little bugs so they do not irritate our eyes. Blinking also relieves pain. If you leave your eyes open to long, they start to irritate, and blinking relieves you of your pain.


The Blinking Process
How does the blinking process occur, you may ask? Well, tears bathe the eye in water to make it “like new” again, after every single blink. Blinking helps seal the eye so when you blink no light gets through; though blinking is so fast that you don’t lose sight of what you are seeing. The upper eye spreads tears across the surface of the eye to wash away dust and irritants and keep the cornea moist. Did you know that tears wash the eye, the same way that wind shield wipers do?




Protection and Light
Your eye absolutely needs protection from dust and dirt which could damage the surface of the delicate cornea in your eye. Your eyes also refresh themselves when you sleep, for it helps your eyes be “fresh and ready to go” the next day. Sleeping also helps your eyes get some rest, for your eyes must stay awake and open almost the whole day. Even if you are blind, you still need to blink because just because light doesn’t enter your eye, dirt and dust enter your eye and need to be gotten rid of. When light enters your brain, the brain reads these signals as a picture of the object, though sometimes when the light is too bright or sudden, your eyes don’t have time to blink or adjust, and your eyes need to blink a lot in order to adjust. Sudden light or rapidly approaching objects both trigger reflex blinking that protects the eye from damage. Sometimes when bright light comes at you so quickly that you are unprepared, your pupils don’t have time to adjust; therefore your eyes hurt. When humans see an object, they actually see light bouncing or reflecting off that object. When light enters the eye, the eye changes the light into electrical signals, which travel through the optic nerve to the brain.


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Figure 2-Parts of the Eye Diagram

Things Getting into Your Eyes
What happens when stuff tries or actually gets in your eye? When something gets in your eye that is unwanted (dust, dirt, or even bugs) then your eyes work ferociously to get it out. Your eyes are delicate and when something bothers them, it irritates them, and they hurt and sometimes turn red from rubbing them or major (or even minor) irritation. Under your eye lids, there is a lot of oil. Whenever something that you don’t like gets into your eyes, the oil glands produce oil. Your eyes also produce water if you haven’t noticed whenever stuff gets into your eyes. The water in your eyes (combined with some oil) drains the unwanted stuff into the red corner of your eye, closest to the nose. That is typically the reason why when you wake up in the morning, you have to “clean” your eyes of all the gross stuff.


Pupils
Your pupils are one of the most important parts of your eye. They handle light. Your pupils change size whenever light changes brightness, or when fast things are coming at your face. In the sunlight, your pupils get smaller because they don’t need to see as much for of all the light, though in the dark, your pupils get bigger because they are trying to see what they can’t see. Another reason why your pupils get bigger in a lot of light, and in dark they get smaller is because when there is a lot of light, your pupils get smaller to block out excess light, and when there is not a lot of light at all they get big to draw in more light. Your pupils blink when light is too bright.


Glossary:

Cornea-The clear coating around your whole eye that protects the iris, the pupil, and other parts of your eye from exposure.

Pupil-The center of your eye; the black part that draws in the light.

Eyelash-The thin hairs along the end of your upper eye lid that bat away any unwanted things including water from irritating your eye.

Eye Brows- Your eye brows help stop water from coming into your eyes.

Eye Lid- These protect your eyes from damage like bugs and other small things; they blink; the eye lids snap shut when fast-coming things are directed towards your face.


Citations:

“Eye.” Britannica Elementary Encyclopedia. Encyclopedia Britannica Online School Edition. Encyclopedia Britannica, Inc., 2012. Web. 27 Sept. 2012.

Macaulay, David.The Way We Work: Getting to Know the Amazing Human Body. Boston: Houghton Mifflin, 2008. Print.

"Nervous system." Compton's by Britannica. Encyclopedia Britannica Online School Edition. Encyclopedia Britannica, Inc., 2012. Web. 27 Sept. 2012.

Walker, Richard. Encyclopedia of the Human body. London; New York: DK Pub, 2002. Print.