Rod+Cells+-+ED

=Introduction= toc Ben was walking outside at night on the sidewalk with me. We were talking and not paying attention to the street. We were almost at the house then there was a car coming, but we couldn't see it. Ben was on the street and the car came closer and closer. He looked and saw the shape of a car so he ran to the other side. That’s why rod cells are an important cell in our body. When it’s dark, rod cells help us see the shapes of things at night.

=Rod Cells=

Did you know that there are special cells in our body, and their only job is to help us see? These cells are called rod cells and cone cells, and are only found in our eyes. They are located in the retina, which is a layer of tissue in the back of our eyes. There are about 120 million rod cells and about 6-7 million cones in our retina. They are important cells because they helps us to see. We can see When the eye sees an image is send to our retina that helps us turn the image around so we can see it right side up. Our retina is a muscle in the back of our eye in which the rod cell and cone cell are located in. Thats how our eyes can see. So you should be happy to have good eyes.

=How Does a Rod Cell React to Its Environment=

Rod cells first react when they come into contact with light that enters our eye. Rod cells mostly react to dim, or low light. First, dim light hits our retina, then a chemical reaction occurs in the rod cell and an upside down image appears on our retina. Remember, the retina is the layer of rod and cone cells that line the back of the eye. These cells in the retina sense light. Next, the retina turns the image around so that we can see it the right way.

The chemical that is formed in this reaction is call ** Rhodopsin **. It is a ** photosensitive ** chemical that creates an electrical impulse in the eye. Rhodopsin is also called visual purple and it is a mixture of protein and vitamin A. Did you ever hear someone say “eat lots of carrots because they help your eyes?” Well, that’s because carrots have lots of vitamin A !! =Rod Cells Help Us With A Lot of Things=

A rod cells job is to process light and help us see in the dark. Rod cells help us see the shapes of things in dark light. There are other cells in the retina, called cones, that help us see in bright light. Rod cells help us see only the colors black, white, and gray. In fact, rod cells can’t tell the difference between bright colors. The cone cells help us see bright colors.

Its interesting because the number of rod and cone cells is different in some animals. Animals have different instincts and habits so the amount of rod and cone cells depends on that. For example, a hawk has more cones than humans because a hawk has to hunt for its food. Hawks have to be able to see small animals from farther away, so they have more cone cells to help them with that. Animals that are **nocturnal** (go out at night and sleep in the day) need more rod cells so they can see better at night.

=Shape and Structure Of a Rod Cell=



A rod cell has a very unique shape. It’s a **receptor** cell, meaning it has to receive impulses, so that is why the shape is different. The cell is shaped like a rod and is divided into two sections. The bottom portion is called “the inner segment.” It has the nucleus and the ** synaptic ending **, (the area where the information travel across). The top part of the rod cell is the disks with the

**rhodopsin**, the chemical that makes the electrical impulse happen.It has two parts because its doing its job in two stages. In the first stage it rod cell is reacting to light It has two parts because its doing its job in two stages. In the first stage it rod cell is reacting to light

=Vision Problems=

The a disease called Retinitis Pigmentosa it can cause you to get blind. It is a disease when the retina is damaged. It is an inherited disease. When you have the disease its usually because the rod cells have decreased. It runs in families so if there is no history then you probably won't get it. Usually the first signs happen in childhood but the vision is not severely limited until early adulthood. The symptoms are loss of night vision, loss of ** peripheral vision ** (side vision), and loss of central vision in the advanced stage. Some people need glasses or contact lenses because they have bending light rays. Glasses help make those light rays straight again.

=Conclusion=

Our Rod and cone cells are like the camera in your body. They help us see a lot of things. Have you ever seen the little dots in your eyes when it suddenly goes dark? That is because our eyes are adjusting to darkness from bright light. Those are the cone cells and rod cells doing their job. Without your eyes you would not be able to see everything in the world so you should be happy that you have rod and cone cells. =References= Works Cited The Eye: Structure and Function Discovery Education, 2004. Full Video.Discovery Education. Web. 19 December 2014. . “The eye struture.” Scince aid. N.p., 9 May 2012. Web. 18 Dec. 2014. . The First Steps of Human Vision. Activities Exchange. N.p., 2015. Web. 21 Jan. 2015. . Padilla, Michael J., et al. Prentice Hall Science Explorer. Boston: Pearson, 2009. Print. “Retinitis pigmentosa.” Pubmed Health. A.D.A.M., Disclaimer, 2013. Web. 23 Jan. 2015. . Szaflarski, Diane. “Rod cell.” How wee see. N.p., n.d. Web. 21 Jan. 2015. . Vison loss. Russel Family Acupuncture. Russel Family Acupuncture, 2014. Web. 19 Dec. 2014. .

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