Rod+Cells+-+SM

=**Introduction**= The puck comes flying in and then all of a sudden the goalie catches the puck in his gloves and the crowd goes wild.Then he freezes the puck and it is a face off. But what you haven't noticed is that the rod cells are controlling the eyes. They are like the captains on a hockey team because they send the signal to the brain so that the brain understands what to do with the picture and stop the puck clean. The rods and cones are like teammates because they both do different jobs to send the picture to the brain. The rod cells absorb the light of the picture and turn the picture upside down, then the cones add the color to the picture so the brain can do its job.



=**Function**=

Rod cells are a very important part of the eye. Rod cells are photoreceptor cells which means that the light hits an object and it reflects the light into your eye. Also the rod cells have partners in the eye and they are called cones.These cones pick up color that can work the best in the brighter light and dimmer light.The human eye contains around 130 million rod cells in one single eye and with about 7 million cones.This means that it takes a lot of effort to send a picture to the brain through the retina, because all of the different cells in the body have a different job to do inside the eye so the process is time worthy. We use Rods and for night vision because only a few bits of light can activate a rod cell.

=**Structures**=

An amazing process takes place as the rod cells enable the human eye to see. (Power Knowledge ¨rod and cones¨)Light hits an object and then it reflects the picture into your eyes.Therefore, the light then enters the cornea since it is being pulled toward the rod cells. Then the cornea helps focus the light light through a small hole called the pupil.Then the light goes through the lens and it hits the rods and the retina. Lastly, the rods transport the light signals into electrical impulses that are transported to your brain through the optic nerve.(Brain Pop ¨Eyes¨ Also the bigger the rod cell is it will help more with transferring the light to the optic nerve because they have a lot more power to transport the electrical impulses.

== =**Eye Diseases**=

Did you know rod cells can cause vision loss? A disease called Retinitis Pigmentosa is the name given to eye diseases that affect the retina. The retina is the light sensitive part of the eye. Retinitis Pigmentosa causes the photo-receptor cells to breakdown in the eye. The photoreceptor cells in the retina detect light. Photo-receptor cells take in and process light and this helps us to see. When photo-receptor cells break down and die, a person will have vision loss. (Natural Human Genome Research center) The most common feature of Retinitis Pigmentosa is the breakdown of the rod cells. The rods cells detect dim light and color. Retinitis Pigmentosa causes the breakdown of rod cells. The disease usually begins with night blindness. Night blindness is like the moment when you enter a dark movie theatre on a bright, sunny day. However, patients with Retinitis Pigmentosa cannot adjust their vision to dark and low light environments.



=**Conclusion**=

Rod cells are like a camera because they are called photo receptor cells and what they do is they convert light into signals that travels to the brain and then the brain takes the picture and registers it so you are able to see the image.And the two main photo-receptor cells are rods and cones, they each contribute information to the brain used by the visual system of the eye.

= = = = = = = = =**Sources**=

Coolidge-Stolz, Elizabeth, et al. Human Biology and Health. Boston, Pearson, 2009. “Eyes.” BrainPOP, 2017, www.brainpop.com/health/bodysystems/eyes/. Accessed 30 Jan. 2017. “Human Eye: 03: Rod Cell.” YouTube, uploaded by DNAunion, 25 Apr. 2010, www.youtube.com/watch?v=EqXld_e9YDM. Accessed 2 Feb. 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. “Rod cell.” New World Encyclopedia, 9 Sept. 2008, www.newworldencyclopedia.org/entry/Rod_cell. Accessed 30 Jan. 2017. wikipedia. 2017, en.wikipedia.org/wiki/Rod_cell. Accessed 30 Jan. 2017.