Rod+Cells+-+EW

=Introduction= toc Imagine walking into a room that is not very bright, though you can still make out everything in the room, when you turn on all the lights you can see everything clear as day. This would not be possible without rod and cone cells. With defects to the **rods** and **cones** you can be blind. =What are Rod Cells?= Rods are receptor cells that respond to light. They work best in dim light and enable you to see black white and shades of gray. When light hits rods and cones, nerve impulses travel to the **cerebrum** through the **optic nerves**. One optic nerve comes from the left and one from the right. The brain turns the image right side up, also it combines the images from each eye to produce a single image. The parts of rod cells are **photo receptor pigment** (a chemical) that allows for light detection and an **axon**, which is the support center within the cell.

This picture shows rods in blue and cones in purple. You can see that there many more rods than there are cones.

= = = = =What is the Difference Between Rods and Cones?= Cone cells, like rod cells, respond to light. Cones enable you to see colors, and rods enable you to see black, white, and shades of gray. Both cells function the same way, but according to the book //Cell Functions// by Jennifer Viegas "cone cells have a larger **nucleus**, more **mitochondria**, and a different shaped photo receptor than rod cells." There are 6-7 million cones and about 130 million rod cells in the **retina** (light sensitive part of the eye).

This image shows/labels how the light hits the eye and you can see what the rods and cones look like and where they are in the eye.

=Eye Defects=

__Colorblindness__- Most vision problems are inherited and are present at birth. People usually have three types of cone cells in the eye. Each type senses either red, green, or blue light. You see colors when your cone cells sense different amounts of these three colors . visit- [|__http://enchroma.com/test/result/normal/?completed=1&summary=normal&axis=-90.00&exta=6.17&extb=6.17&lcs=1.52__] to take a color blindness test to see if you are **colorblind**. __Retinitis Pigmentosa-__ An eye disease caused by the rod cells breaking down. This disease causes breakdown of **photoreceptor cells** (cells in the retina that detect light) and you see what the second picture below shows. RP is an inherited d isease that affects the retina. Rods are concentrated in the outer portions of the retina and are triggered by dim light. 100,000 people in the U.S. have RP.





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Watch this video  [] to learn even more about rods and cones

=Conclusion= In conclusion, rods and cones are very important because they help you see at night and the clors of the rainbow at day. Not too many people know a lot about rods and cones, but without them, you would have serious effects to your vision.

=References=

Works Cited “Eye´s Rods and Cones.” Inner Body. Inner Body, 2015. Web. 17 Feb. 2016. . Foundation Fighting Blindness. “Retinitis Pigmentosa.” Foundation Fighting Blindness. Foundation Fighting Blindness, 2016. Web. 7 Mar. 2016. . “Learning about Retinitis Pigmentosa.” National Human Genome Research Institute. National Human Genome Research Institute, 27 Dec. 2013. Web. 8 Mar. 2016. . Viegas, Jennifer. Cell Functions, Understanding How Cells Work. N.p.: Rosen Publishing Group, n.d. Digital file. Vision Discovery Education, 2004. Video Segment Discovery Education. Web. 17/2/2016. . Vision: Photoreceptors Rods and Cones. Narr. Khan Academy. 2013. Film.