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=Introduction= toc A photoreceptor cell is an important cell in the retina that helps you see during the day or the night. Two specific cells, rods and cones, are the main cells in your everyday vision. Every time you look at something, your rods and cones are helping you see it. Rods and cones work from when you wake up all the way until you go to sleep. These rods and cones never stop, unless confronted by their arch nemesis, Retinitis Pigmentosa. A **photoreceptor cell** is a specialized cell in the retina that is able to make light into electrical signals (also known as **phototransduction** ). Photoreceptor proteins in the cell consume photons which makes the cell’s membrane change itself to work to its full potential. Rod and cone cells are two types of photoreceptor cells. A photoreceptor cells are important to the human body because they help you see. Rods and cone cells are the main helpers in helping you see everyday things, like a banana or a table. However, when we see a banana it's yellow, but only because our brain and our cells process it like that. In reality, a banana could be purple but we will never know because our eyes process it differently. Anyways, photoreceptor cells are able to make light into signals, or **phototransduction**. **Phototransduction is when a photon is turned into a signal and carried to one cell to another.** This helps us piece together pictures. The two cells talked about in this article are the rod and cone cells. Rod and cone cells are also part of this "system", as they are photoreceptor cells and photoreceptor cells are able to complete phototransduction. =**Structure of Rod and Cone Cell**= Rod cells and cone cells look very simple on the outside: A rod, shaped like a rod, and a cone, shaped like a cone. But on the inside, these cells are very busy! Inside these cells you see different organelles such as the **mitochondria, rhodopsin, and** **synaptic endings.** In the picture to th e right, you can see the abundance of ** mitochondria ** in the rod and cone cells. ** mitochondria are ** **organelles that are considered the powerhouses of the cell because they produce a lot of the cell’s energy**. Mitochondria are v ery important to the rod and cones cells because rod and cone cells need a lot of energy in order to be able to see at their best and deliver messages to one another saying what they see! If they didn't have a lot of mitochondria, they wouldn't be able to work because they wouldn't have any energy! Mitochondria are the producers of energy in the cell, so imagine this: we eat food, so that is our nutrients. However, without a digestive system (or, in this case, mitochondria) this food would be useless because we wouldn't get any energy out of it. The mitochondria, like our digestive system, work hard to give the cell/our bodies energy to keep moving. Also inside rod cells only are **rhodopsins**. **Rhodopsin are a pigment in the rod cell that are very sensitive to light.** See how there is a relationship between the organelle and the cell? The rhodopsin are sensitive to light, and so are rod cells. This is because rhodopsin are the main helpers in seeing in low light. Have you every been in a dark room, but you can still see? This is because a rod cell that contains rhodopsin is better at seeing than a cone cell, that doesn't have rhodopsin. That's also why you might be able to see in the dark but you may not be able to see much color. The final organelle I will talk about are the **synaptic endings**. Once a rod or cone has energy to work (mitochondria) and able to see (rhodopsin in the dark) it has to send all of its information to each other and eventually to the brain. But there needs to be a way for the cells to communicate (and no, they don't have CELLphones or email). This is what a synaptic ending is for. On the end of every rod and cone cell, you can find a synaptic ending. **A synaptic**** ending resembles little tentacle-like things that, when they touch, transmit signals to one another. ** These synaptic endings give off these signals super fast so you can see everything you're seeing right now. Pretty cool, huh? =**Rod and Cone: Same But Not**= A rod cell works in black and white, and is, in a way, color blind. On the other hand, a cone cell can see in 3 different colors (red,blue, and g reen). When mixed together, the different colored cones make the different colors we see on a daily basis. Ever wonder why it’s hard to see colors in the dark? Well, that’s because a cone cell functions better in the light than in the dark. However, you can probably still see, thanks to rod cells. Even though they cannot detect color, they function better in the dark than in the light. Think of it like this: your rod and cones are activated by a switch; in this case, the switch is light. The rod cell switch is off while you are in light, while cones are on. Shut off the lights, and the cone cell switch goes off and the rod cell switch turns on. ( Please note that rods still work in the light, just not as well, and cones still work in the dark, just not as well). Rods and cones are vital to your vision, and even though they are incredibly different, they collaborate together to create the amazing phenomenon of sight. =**Retinitis Pigmentosa: The Enemy of Your Eyes**=
 * Photoreceptor Cells **
 * Photoreceptor Cells **



**Retinitis Pigmentosa is a disease where the person who gets it can get horrible vision and, in some cases, become blind**. Retinitis Pigmentosa is not contagious, but it is inherited from another family member. People with Retinitis Pigmentosa are born with the disease already in them, or it is developed with some syndromes, such as Bassen-Kornzweig disease or Kearns-Sayre syndrome.

There are many different symptoms and signs to show cases of retinitis pigmentosa. Some symptoms include:


 * ** Nyctalopia **, or the inability to see well at night
 * **Central vision**, or loss of peripheral vision
 * **Peripheral vision**, or the loss of central vision
 * Slow to adjust from dark to light
 * Slow to adjust from light to dark
 * Blurry vision
 * Unable to identify different colors easily

Thankfully, there are multiple medications and treatments to help manage retinitis pigmentosa. Some of these treatments include:

=**Where Are Rod and Cone Cells Found?**=
 * **Docosahexaenoic acid,** a fatty acid and antioxidant\
 * **Acetazolamide,** which helps improve vision function
 * **Lutein/zeaxanthin,** which helps increase macular pigment
 * [[image:http://starizona.com/acb/ccd/advimages/eye01.gif width="227" height="227" align="center" caption="This picture is a simple diagram of where you can find rod and cone cells in the eye. (Please note you can find rods and cones in other places, this is just to portray a general idea of where they are found)."]]

A rod cell and a cone cell both are in the eye, but some are more plentiful in places than others. As you can see in the picture to the right, the cone cells are plentiful exactly behind the lens, while the rod cells are found to the left and right of the cones. The cones are in the middle and the rods aren't because you use rod cells more in your peripheral vision, which is why you may be able to see things in your peripheral vision move quicker, as rods are amazing at sensing motion. However, rods and cones are in more places than just the back of the lens. There are an abundance of cones in fovea, while the fovea contains no rod cells. Rods are found in every other part of the eye. =**Conclusion**= Photoreceptor cells are the geniuses of the eye. Since rods can detect as little as 5 photons of light and cones are able to see in color, they are the geniuses of sight. Turning light into electrical signals (phototransduction) and sending them through synaptic endings is something only the photoreceptor cells can do. These cells work all day to keep up with you. Next time you look at something, like a book or anything really, thank your rod and cones cells for helping you. =**References**=

Picture: [] http://starizona.com/acb/ccd/advimages/eye01.gif Works Cited Green, Dan, and Simon Basher. //Biology: [life as We Know It!]//. New York: Kingfisher, 2008. Print. “Photoreceptor Cell.” //Wikipedia//. Wikipedia, n.d. Web. 23 Jan. 2015. . “Your Eyes.” //Kids Health//. Nemours, 2015. Web. 23 Jan. 2015. .