Rod+Cells+-+WM

=Introduction= toc Imagine you are in a dark room. You open your eyes struggling to see where you are. Your rod cells kick in and everything becomes more clear. Working like a flashlight, the rod absorbs the little light there is and makes a clear picture. Rod cells are one of the most important cells in your body. They absorb light and make a picture to send to your brain. They are specially structured in order to do this. However, some people’s rod cells don’t work so easily. People who suffer with retinitis pigmentosa have a hard time seeing with their rods, whether it be not seeing in dim light, or losing peripheral vision. Continue to read in order to learn more about these cells.

The Function of the Rod
Have you ever wondered how your eyes can develop a image so quickly? Or how these images get to your brain? Well thank the photoreceptors in the back of your eyes. There are two types of photoreceptors and they are located in the back of your eye. These receptors are called rods and cones. There are over 120 million rods and only 6 or 7 million cones. (Brain Pop-Eyes) Rods can be triggered by a single light photon, well cones are not as reactive. (Brain Pop-Eyes). Light is directed through the lens and is absorbed by rhodopsin at the top of the eye. Rods pick up images in black and white, well cones pick up color.(Miller et al 106). Once these images are received in the eye it is sent to the brain through the optic nerve. (Miller et al 106). Once the images gets to the brain, the brain flips it around and processes it. This process is not easy on the rods and cones, though. Let’s take a look at what structure enables it to perform this process.

=The Rod Structure= Picture a pancake stack like structure that almost magnetizes light towards it. Well this is a perfect example of the rod. The rod is a stick like structure that has many features that help it do its job. Starting with arguably the most important feature, the top of the rod is packed with many layers of cell membrane, or “disks”. (Pearson 194) Many people compare these disks to looking like a stack of pancakes, as they are layered on top of one another. The rod is constantly in a cycle of getting rid of old disks at the top, and generating new ones at the bottom. These disks are packed with a chemical called rhodopsin. Rhodopsin absorbs light to the rod. (Miller 106) You may be wonderi ng how does such a small cell do all this? (A rod cell is only .00007874 inches in diameter by the way!) Well the answer to that question is the number of mitochondria. A rod cell could have 4-5x as many mitochondria than the average cell, which helps it produce so much energy. (Miller 106) Finally, all the way at the bottom of the rod is the synaptic terminal. It works almost like a n airport, by receiving electric signals from the rest of the rod, and sending those exact signals through the optic nerve and upto the brain. However, not everybody's rods work so proficiently. Some people have diseases that affect their rods.

= = = = A diagram of a single rod cell (Above) =Eye diseases= Rods and cones are vital cells in the body. This is why it is a very challenging task for people who have been diagnosed with retinitis pigmentosa or other diseases that affect the rods. Retinitis pigmentosa is a group of diseases which affects the rods. Retinitis pigmentosa usually starts with night blindness(seeing poorly or not at all in dim light). As the disease progresses you could then be diagnosed with tunnel vision, a disease where you lose your peripheral vision, and can only see out of a small center field. Finally, as you may assume if this disease progresses any more you could possibly become blind. (Goldberg) There are plenty of other diseases that affects these cells. One example is a disease that affects the cones. Color vision deficiency, more commonly known as color blindness is a disease that affects approximately 1 in 12 men and 1 in 200 women in the world, so it may be more common than you think. Contrary to popular belief, color blindness is very rarely lacking complete vision, but usually is just difficulty telling certain colors apart. For example, green may appear brown in a l ot of cases. This is caused by abnormalities in the pigment of the cones. (“Eyes” ) media type="youtube" key="hHiu3cTMgMs" width="234" height="174"Retinitis pigmentosa information (Right =Conclusion= Now I hope you can see how vital the rod cell is to everyday living. The structure of the rod helps it do its job of absorbing and sending pictures to the brain. Although many people count on these cells to live their daily lives, some people are not as fortunate, as they can have defects that do not let their rods work as well. I hope this enables you to be grateful for your rods and to understand how important these cells are for daily living. For more information on rod cells, visit http://health.howstuffworks.com/mental-health/human-nature/perception/eye2.htm

=References=

“Eyes.” PowerKnowledge Life Science, Rosen Publishing, www.pklifescience.com/article/426/eyes. Accessed 30 Jan. 2017. “Eyes.” BrainPOP, www.brainpop.com/health/bodysystems/eyes/. Accessed 30 Jan. 2017. Goldberg, Morton F. “Eye.” World Book Student. World Book, 2017. Web. 30 Jan. 2017. Miller, Kenneth R., and Joseph S. Levine. Biology. 4th ed., Englewood Cliffs, Prentice Hall, 1998. Neuroscience for Kids. Eric H. Chudler, faculty.washington.edu/chudler/retina.html. Accessed 30 Jan. 2017. Tortora, Gerard J., and Nicholas Peter Anagnostakos. Principles of Anatomy and Physiology. 6th ed., New York, Harper & Row, 1990.