HOW DOES YOUR SENSE OF SIGHT WORK?

contributed by: Gracie M.

Date of publication 9/30/11
The eyes are a natural phenomenon they work together with your nervous system and your brain to let you see objects and it happens so quickly, humans can’t tell what is really happening. Sight is really based off of light, when you are looking at something light reflects off of it and into your eyes, that’s why you normally can’t see very well in the dark. Light is let in by your lens and then is projected onto the retina. The retina is a very important part of the eye. It is around the size of a bottle cap and has about 126 million photoreceptor or light receiving cells. The light receiving cells change the light energy into electric energy. There are also two different types of photoreceptor cells, these cells are called cones and rods. Cones let us see color and detail, and rods let us see white, grey, and black. After the retina changes the light energy into electric energy the energy sends the information that you see to the optic nerve. The optic nerve is a long nerve that travels from your eyes to your brain.When the electric energy reaches the brain is sent the part of the brain called the thalamus. The thalamus I the part of the brain that sorts the information and sends it on. Things you see with the right side of your eye are sent to the right side of the brain through the optic nerve and it is the same with the left side of your eye the part of the brain where the information goes is called the right and left visual cortex. Everything above happens in a fraction of a second, it is so quick that we don’t even know what is really happening.



GM_Sense_of_Sight_Internet_pic.JPGGM_Sense_of_Sight.JPG
This is a picture of the information traveling to the right and This is a picture of the inside and outside of the eye
Left visual cortex by the optic nerve







RELATED TOPIC 1
Why do eyes have color?
You get your eye color from the genes in your family. Brown is a dominant color for eyes. Blue eyes only show up when there are no genes for other colors. Eye colors like green and gray show up when genes for eye colors are mixed together.


RELATED TOPIC 2
Why do my eyes sometimes turn red in a photo?
Eyes turn red in a photo sometimes because when you look straight into the camera, the flash may reflect of your retina, somewhat like a mirror. It becomes red because there are many blood vessels behind your eye and when you look at the camera it looks red.





GLOSSARY
Phenomenon;
Something that is impressive or extraordinary
Photoreceptor;
A receptor stimulated by light.
Visual Cortex;
The portion of the cerebral cortex of the brain that receives and processes impulses from the optic nerves.








CITATIONS

Web
Compton’s Encyclopedia. Encyclopedia Britannica. Encyclopedia Britannica, Inc., 2011. Web. 9/26/2011

Book
Ellen Weiss. The Sense of Sight. New York: Children's Press, 2009. Print