Rod+Cells+-+HM

=Introduction=

You wake up when you hear something outside. You get up and your eyes need to adjust to the dim moonlight outside and you finally see that it's only your cat scratching on the door. You are able to see this because of your rod cells that work well in dim light. Your rod cells are made to take in light and transport the image to your brain. The structures of the rod cell like rhodopsin absorbs light and then it signals your rod cell. Without it your rod cell couldn’t function well. Rod cells aren’t immortal. They can be destroyed by a disease called retinitis pigmentosa.

=Function of rod cells= toc As you are looking at this sentence your rod cells are sending electrical impulses to your brain. You are receiving this image because of your rod and cone cells. Humans have more than 120 million rod cells in their retina.(Miller 107) Rod cells are different than cones. They can detect light but can't detect color. Rod cells work best in dim light. Rod cells are located in your retina and they look like rods.(Miller 106) Rod cell are connected to your brain from the optic nerve. The electrical impulses that they transport to your brain are the images and they are interpreted by your brain and then you can see the image. There is a process that happens that lets you see an image. First light hits an object and it reflects into your eyes. After that the light enters the cornea and it is pulled toward the rod and cone cells. Then the cornea helps focus the light through the small hole which is called the pupil. After that, the light goes through the lens and it hits the rods and cones. Next the rod cells transform the light signals into electrical impulses that are then transported to your brain on the optic nerve .( Padilla et al 194 ) The image is upside down when it gets to your brain and your brain flips the image over.(“Rod Retinal cell” )Finally it interprets the image and that lets you see the image. That's how you can see. That's also the reason why you are able to read this paragraph. media type="youtube" key="YcedXDN6a88" width="560" height="315" align="left"

= = = = = = = = = = = = = = =Structures of the rod cells= Did you know that the rod cell has more mitochondria than any other cell?Well rod cells have 4 to 5 times more mitochondria than other cells. The cell membranes on the rod cells contain a pigment called rhodopsin.(Miller 107) Rhodopsin is a chemical in the rod cell. It absorbs the light and it signals the cell that light has reached the cell. The reason why you can see is the electrical impulses going to your brain. The electrical impulses get to your brain by traveling from neuron from neuron because of the synapse.( Padilla et al 195) The synapse makes the neuron pass an electrical impulse to another neuron. That's how the signal reaches your brain. For example it's kind of like a car that reaches a river. Then it has to take a ferry across the river so it can get to its destination which in this case would be another neuron. That's how the electrical impulses get to your brain and that's why you are able to see.

 =Real world connection=

Your rod cells usually work well with your structures but there are diseases that can change that. A disease than can kill your rod and cone cells is called Retinitis pigmentosa. Retinitis pigmentosa is a group of diseases that can kill your rod cells.(“Learning About Retinitis Pigmentosa”) A side effect to this disease is not being able to adjust your eyes in dim light. Also if you have this disease you can’t look right or left without turning your head. It's kind of like looking through two straws. You can’t get this disease from any environmental factors. The only way to get this disease is if you're born with it. Retinitis pigmentosa kills your rod cells because you have a bad gene. A doctor can tell if a child has this disease around age 10.(“Learning About Retinitis Pigmentosa”) There is no known cure for this disease but they are working on a cure. On thing that they think could work is transplanting healthy genes into the retina. This is something that they could do but they don’t know if it's safe to do on humans. This is how retinitis pigmentosa affects the human eye. Maybe eventually scientists can figure out a cure for this disease?

= = =Conclusion=

All of this may see a bit confusing but it's worth looking further into. Imagine life without your rod cells. You wouldn’t be able to see well and you wouldn’t be able to see in the dark. Rod cells are the reason of why we can see. The electrical impulses from your rod cell help you see. Also Rhodopsin absorbs the bright and dim light that comes through your pupil. Your rod cell isn’t indestructible. They can be destroyed by diseases that there is no cure for. We shouldn’t take our rod cells for granted or maybe we should. Well Helen Keller said”It is a terrible thing to see and have no vision.

=References= Works Cited Cells Visual Learning Company, 2008. Full Video Discovery Education. Web. 30/1/2017. http://www.discoveryeducation.com.

The Editors of Encyclopædia Britannica, editor. “Rod.” Encyclopædia Britannica, 7 Aug. 2007, www.britannica.com/science/rod-retinal-cell. Accessed 30 Jan. 2017.

“Eyes.” BrainPOP, 2017, www.brainpop.com/health/bodysystems/eyes/. Accessed 30 Jan. 2017.

“How the Eye Works Animation - How Do We See Video - Nearsighted & Farsighted Human Eye Anatomy.” Youtube, uploaded by Animed, 3 Apr. 2016, www.youtube.com/watch?v=YcedXDN6a88. Accessed 4 Feb. 2017.

“Learning about Retinitis Pigmentosa.” NIH, 27 Dec. 2013, www.genome.gov/13514348/. Accessed 30 Jan. 2017.

Miller, Kenneth R., and Joseph S. Levine. Biology. 4th ed., Englewood Cliffs, Prentice Hall, 1998.

Padilla, Michael J., et al. Prentice Hall Science Explorer. Boston, Pearson Prentice Hall, 2007. Tortora, Gerard J., and Nicholas Peter Anagnostakos. Principles of Anatomy and Physiology. 6th ed., New York, Harper & Row, 1990.

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