Rod+Cells+-+KE

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** Introduction ** Picture this. You are outside and it is around 8:30. You look up into the sky there are millions and billions of stars. You are seeing these stars with a cell in your retina called ** rod cells **. These cells are meant to work when it is dark out. They work at levels of low light. Without these cells you wouldn't be able to see anything at night time like stars. Better yet, you wouldn’t be able to see anything at all.

= Why are Rod Cells Important? = Rods and cones are two cells in your retina. The rod cells let you see vision at low light levels. the rod cell is a photoreceptor in your retina that lets you see things while it is dark out. Rods are important because they are used for seeing shades of gray dim light. They allow us to see shapes and movement. These cells don’t always work when you need them to to see. They can get many diseases as well. Without Rod cells, we wouldn’t be able to see.



The Functions of Rod Cells Rod cells are a cell in the retina that allow you to see when it is dark out. There are about 6,000,000 more rods than cones in the retina. If you star out into the moonlight at night, you cannot see any color. Rod cells are concentrated at the outer edge of the retina and are used in peripheral vision. These rod cells are called photoreceptor cells. They function in less intense light. = The Structures Of Rod Cells = There are two types of photoreceptor cells in the retina, which are rods and cones. Rods handle vision at low light levels which is **scotopic vision**. Scotopic vision is the eye under low light level. They don’t produce color vision and have a **low spatial acuity.** Low spatial acuity means that you can't see things as well as others. For an example, if you were to look at the white board in a classroom and it has a word on it, if you were 2twenty feet away and ten other people were 25 feet away and you couldn´t make out the word, but they can, this means you have a low spatial acuity because most people could see what he word was and you couldn´t from closer up. Different from rods, cones handle light at high levels which is **photopic vision**. Photopic vision is the eye under high light levels or a **high spatial acuity( the opposite of low spatial acuity).** They are capable of color vision and have a high spatial acuity. There are 3 types of cones in the retina, The short-wavelength sensitive cones, the middle-wavelength sensitive cones, and the long-wavelength sensitive cones. They are called the S-cones, M-cones, and L-cones for short. media type="youtube" key="r5RkXV3emLY" width="560" height="315"

= What Diseases Affect Rod Cells? = = = Rod cells also have diseases that can attack them as well as working in the retina. One disease that can affect retinitis pigmentosa. Retinitis pigmentosa is the name of a group of diseases that affect rod cells. RP causes the breakdown of photoreceptor cells (cells in the retina that detect light.) When the photoreceptor cells break down and die, patients experience progressive vision loss. RP is an inherited disorder. It is not caused by injury, infection, or any other external or environmental factors. People suffering from the disorder or disease are born with it programmed into their cells. You can get this disease/disorder as early in your life as age 10. CRD's are another one of many diseases. Like RP, it is progressive and there is no way to cure this disease right now. They may have several syndromes but will ultimatley lead to vision loss or blindness = =

= How Do Rods and Cones See Light/Dark? = Rods cells are made up of an inner segment, outer segment, the cell body, and the synaptic region. The outer segment has a bunch of close together disks surrounded by membranes. They contain the photoreceptor **rhodopsin**. The synaptic region is the site where the rod cell gives its information to neurons in the retina. These neurons connect with ganglion neurons. whose axons form the approximately one million fibers of the optic nerve. Rods and cones are very alike in many ways. Rods cells are sleaker than cone cells ==

= Conclusion = Rod cells are the things that make you see and if you didn't have them, you wouldn't be able to see. Researchers are still trying to find new ways too see without rod cells and also trying to create rod cells themselves. As you can see, pun intended, rod cells are very important to the human eye. As the mysteries are unsolved about rod cells, it is only to see what happens to rod cells.

References

** Works Cited ** ** “Learning About Retinitis Pigmentosa.” National Human Genome Research Institute. N.p., n.d. Web. 27 Dec. 2013. . **
 * Carl Bianco “How Vision Works” 1 April 2000. **
 * HowStuffWorks.com.  17 February 2016 **
 * “The Eye.” science aid.co.uk. N.p., n.d. Web. 9 May 2012. . **
 * “Eye’s Rods and Cones.” InnerBody.com. N.p., n.d. Web. 10 Mar. 2016. . **
 * Grade(s) 6-8CC©2004 Discovery Education **