Rod+Cells+-+AU

=**Introduction**= Have you ever looked at a rainbow in the sky and weren’t able to see the different colors or looked at anything in black and white and weren’t able to see? If you didn’t have rod and cone cells then you wouldn’t be able to see these things. The eye has different parts, how do they work together to make us be able to see. There’s differences between rod and cone cells but they work together to help us see. There are also differences between near and farsightedness they reflect off of your rod and cone cells. There are ways to break or damage rod cells because they’re sensitive this is one of the many eye problems someone could have. = = =**Different Parts of the Eye**= The eye is an organ made up of three main layers. The outer layer is the cornea- the transparent layer forming the front of the eye and the sclera- the white outer layer of the eyeball. At the front of the eye it is continuous with the cornea. The middle layer is the iris, a flat, colored, ring-shaped membrane behind the cornea of the eye, with an adjustable circular opening (pupil) in the center, lens- the crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina , and ciliary muscle, the part of the eye that connects the iris to the choroid. It consists of the ciliary muscle (which alters the curvature of the lens), a series of radial ciliary processes  (from which the lens is suspended by ligaments), and the ciliary ring  (which adjoins the choroid). And the inner layer is made up of the retina, a layer at the back of the eyeball containing cells that are sensitive to light and that trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed and the optic nerve- each of the second pair of cranial nerves, transmitting impulses to the brain from the retina at the back of the eye.

=**Differences Between Rod and Cone Cells**= In your eyes there are two different cells, rod and cone cells. Although both of them help you see black and white and color, they do have some differences. According to the book titled Human Biology and Health, rod cells (to the left) appearance is long and narrow and cone cells (to the right) look like a cone-shaped hair comb. Both cells have a axon, which is the long threadlike part of a nerve cell which impulses are conducted from the cell body to other cells. The only differences between rod and cone cells is that cone cells have a larger nucleus, more mitochondria, and a different shaped photoreceptor pigment region and cone cells can detect color and rod cells only work in black and white. =**Differences Between Near and Farsightedness**= Nearsightedness is when you can see objects that are closer to you but you can’t see objects that are farther away. Nearsightedness is when the eyeball is too long so light has to travel a farther length to actually reach the retina. Farsightedness is when you can see far away but you can’t see things that are closer to you. Farsightedness is when the eyeball is too short and the object that you’re looking at doesn’t focus good on the retina. = = =**Different Eye Problems**= One eye difficulty is color blindness. Color blindness is when a person’s color perception is different from people without color blindness. When you have color blindness you can have one of three. One type is red-green color blindness which is the most common type of color blindness. Another type is blue-yellow color blindness. And the last type is total color blindness which is very rare. Color blindness is caused by abnormal photopigments that are in cone cells inside the retina. It can also be caused by a physical or chemical change to the eye, optic nerve, parts of the brain that process color and also with old age. Color blindness can make life difficult because it will be harder to read color-coded information, if you have red-green color blindness it might be hard to read a green chalk board while someone is using yellow chalk, art class may be difficult, and if a person is younger and has color blindness they might not want to eat certain foods because the color looks less appetizing. If you want to find out if you have color blindness click on this link and take the test. http://enchroma.com/test/instructions/

=**Conclusion**= Rod cells are like your seeing eye dogs. They help you see things that if you didn't have rod and cone cells you couldn't see. Rod cells have a long and narrow shape to fit in the back of the eye so they can help you see. Rod cells are an important cell because they help you see colors and black and white and because they mediate diverse kinds of vision. =**References**=

Claydon, Stephan. “The Eye.” Science Aid. Science Aid, 9 May 2012. Web. 24 Feb. 2016. . Coolidge-Stolz, Elizabeth. Human Biology and Health. Boston: Pearson Education, 2007. Print. “Eyes.” PowerKnowledge Life Science. The Rosen Publishing Group, Inc., 2016. Web. 24 Feb. 2016  “Eye’s Rods and Cones.” InnerBody. HOWTOMEDIA, n.d. Web. 24 Feb. 2016. . “Facts about Color Blindness.” NIH. Turning Discovery Into Health, Feb. 2015. Web. 26 Feb. 2016. . The Retina Discovery Education, 2004. Video Segment Discovery Education. Web. 17/2/2016. . Urquhart, Jackelyn. A Journey through the Human Eye. TedEd. Ted Conferences, n.d. Web. 26 Feb. 2016. . Viegos, Jennifer. Cell Functions Understanding How Cells Work. N.p.: The Rosen Publishing Group, 2005. Print. Vision Discovery Education, 2004. Video Segment
 * Discovery Education. Web. 17/2/2016. . **

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