Rod+Cells+-+NK

=Introduction= toc  There are over 120 million Rod cells in the retina of your eye, working together to let you see a cars shape down the street so you know when to cross the street so you can get home in time for dinner, to see an enemy to take out during the night, or to go to the bathroom in the middle of the night. Rods are made to work with Cones to give you vision of what's around you from the retina. With its rod shape, and its positioning, it will get you the partial scotopic (night vision) you need so you can be safe. But the retina is not safe, disease can strike and that 120 million can shrink, sometimes to nothing.

=Job of the Rod Cell=


 * Rod Cells ** retrieves light in almost any lighting condition but is especially useful at night. They are a type of sensory neuron, which sends a message in the format of nerve impulses to a location by sending the impulses through other neurons.

The surrounding neurons has the nucleus, arm like extensions called dendrites, and an ** axon **, a tube that connects to a tip. **Dendrites** transfers nerve impulses to the neurons body, while the axon does the opposite; carry away impulses away from the cells body. Impulses start at the Dendrite and move down the Axon away from the cell body into a tip, which transfers the impulse to another neuron. There can be any amount of dendrites in a neuron but there is always 1 axon.

=Location of Rods=

The Rod Cells as well as cones, are located in the retina of the eye The **retina** is the innermost layer of the eye and carries nerve impulses to the optic nerve, which sends them to the brain. The retina is inverted, meaning light must reach the back then bounced into rods and cones. The brain sees the image upside down as well as other effects, so the brain corrects these mistakes and as a result, we can see.

In the retina, the layout is ganglion cells, inward to bipolar cells, connected to rods and cones, lastly the pigmented retina. **bipolar cells** bring the light image to **ganglion cells** which sends images to the thalamus, (which relays signals of consciousness, sleep, and alertness) hypothalamus, (which controls ** A diagram of the back of of the retina. **

the release of hormones) and **mid-brain**, or the mesencephalon (which is a part of the nervous system, and works with vision, motor control, awake/sleep, and hearing). In The retina, there is approximately 4 to 5 rods then a cone, which also means rods outnumber cones 20:1. This can affect your vision by getting more accurate light.

=Shape of Rods=

Rod Cells are shaped like a rod of course. In the rod cell, there is a synaptic terminal, an inner segment, and an outer segment.

The **synaptic terminal** makes a synapse with another neuron. The 2 segments, inner and outer, are connected by a cilium, which is a fine hair. The inner segment holds the nucleus and organelles. The outer segment is pointed inward towards the back the eye which has light absorbing materials and also has **rhodopsin**, a pigment that filters light by constantly bending a vitamin A with opsin.

=**Rods vs Cones**= Rod Cells gets light and can get you partial night vision in 45 min of darkness, they outnumber Cones in the retina, and they are smaller than cones. Rods end up getting a moonlight like color on objects. While **Cone cells** get color and clarity, they are less sensitive to light and they have color sensitivity/vision, they are outnumbered to rods 20 to 1, and they are larger than rods. Cones boosts your vision with color and clarity.

=Disease?=

There is a disease called ** Retinitis Pigmentosa **, that damages the retina, which is a layer of tissue that turns light images into nerve signals and sends them to the brain. Retinitis Pigmentosa can make you lose vision, and possibly enough to make you blind. Sadly there is no treatment or cure for this. Retinitis Pigmentosa demolishes light receptors, causing the eye to not pick up as much light than it can pick up. It is a progressive disease. The disease starts by attacking rod cells, decreasing your ability to see in the dark. The disease starts to get noticed by the patient by Retinitis Pigmentosa attacking cones and other parts of the retina, reducing the patients vision over time.

=Conclusion=

Rod cells are like solar panels, collecting the light photons. They convert that light into nerve impulses and it goes on to the brain, all 120 million of them to get you your vision. They are positioned and shaped to get the most light it can with the help of cones. They help get you scotopic vision and overall everyday light and help your senses function to keep you safe, all from the back of the retina.

=References=

Works Cited “Anatomy of a Rod Cell.” Wikipedia. Wikimedia, n.d. Web. 20 Jan. 2015. . Direction of light. BioNinja. N.p., n.d. Web. 20 Jan. 2015. . The Eye: Structure and Function Discovery Education, 2004. Full Video. Discovery Education. Web. 19 December 2014. . Padilla, Michael J., et al. Prentice Hall Science Explorer. Boston: Pearson, 2009. Print. “Retina.” mrotheory. N.p., n.d. Web. 15 Jan. 2015. . “Retina Bipolar Cell.” Wikipedia. Wikimedia, n.d. Web. 15 Jan. 2015. . “Retinal Ganglion Cell.” Wikipedia. Wikimedia, n.d. Web. 15 Jan. 2015. . “Rod.” Encyclopædia Britannica. 2014 Encyclopædia Britannica, Inc., 19 Mar. 2013. Web. 18 Dec. 2014. . “Symptoms.” Wikipedia. Wikimedia, n.d. Web. 20 Jan. 2015. . Wertenbaker, Lael Tucker. The Eye: Window to the World. Washington: U.S. News, 1981. Print.