Neuron+-+EM

=Intro= toc Anyone reading this knows how much it hurts when you touch something hot and don’t expect it. That is your neurons at work, sending lightning-fast electrical impulses to your brain. Without your neurons, you wouldn't have known to pull your arm away and would possibly burn your arm on the stove. Neurons are an essential part of the human nervous system, and without them you wouldn't be able to complete everyday functions. = = =**Ch.1 What Are Neurons?**= Neurons are nerve cells that that transmit nerve impulses from one part of your body to your brain. Neurons enable you to feel what you are touching. Without neurons, you wouldn't really wouldn't be able to function. Neurons work lightning fast, literally, as mentioned earlier, they use nerve impulses, or, electricity to send messages to the brain.

There are three types of neurons. Sensory neurons, motor neurons, and interneurons. Sensory neurons provide stimulatory feelings. Motor neurons are made to react fast, hence the name, and tell the brain to react to pain. Interneurons connect other neurons aside from the dendrites and axons. Although they do different things, all three neurons have a very similar anatomy with minor changes in axon placement. Scientists have estimated that there are more than 1,000 billion neurons working together in the human body. The spinal cord area has the largest concentration of neurons in the human nervous system.



=**Ch.2 How do Neurons Work so Fast?**=

The shape of neurons can vary, but they all have the same general shape. Neurons are somewhat shaped like arms because they need to be close to each to transmit nerve impulses. Nerve impulses are sent by the axon to the dendrites of another axon to the next, and eventually to the brain. As a result, the process of transmitting to the brain is very quick as long as the neurons are near each other. Because of the way they function, neurons form a network so that the impulses can reach your brain from any neuron in your body, there is never a lone neuron.

The axon is protected by the myelin sheath, which also enhances the speed in which it transmits to the next neuron. The Schwann’s cell is located under the axon and creates the myelin sheath. Every axon has a nucleus which is surrounded by the cell body were the dendrites are located. Axon terminals are what transmit the nerve impulses to the dendrites of another neuron. Dendrites are short branched extensions of a neuron, along which receive nerve impulses from the axon. On the other hand, the axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body.

http://www.wpclipart.com/medical/anatomy/cells/neuron/neuron.png =**Ch.3 Are There Different Types of Neurons?**=

Neurons come in various shapes and sizes there are three distinct types of neurons. Interneurons, Motor neurons, and Sensory neurons. Each type of neuron is specialized for a certain task. **Interneurons** are connectors that bridge between motor and sensory neurons. **Motor neurons** are made to react quick and relay pain to the brain. Finally, **sensory neurons** relay sensations such as feeling or warmth, etc.

As mentioned earlier, neurons come in many shapes and sizes, this is why interneurons are needed. The help connect interneurons and sensory neurons which are found in different areas of a body. Interneurons are the only way the two different types of neurons can project nerve impulses to each other. Interneurons basically simplify the messages so that other neurons can transmit them.

Motor neurons have to be VERY fast. Because they tell your brain when you are feeling pain, they have to work fast so that you know when something hurts, when they don’t work, bad things happen. Motor neurons are made, and mostly concentrated around the spinal and vertebral.

Sensory neurons, send sensations to the brain. These include, warmth, cold, touch, taste, and other things of that nature. They are the most widespread throughout the body but do not work as fast as motor neurons.

=**Ch.4 How do Neurons Work so Fast?**=

Neurons have to react fast. They control your reaction to touch, and other senses. Say you touch a hot stove and burn your hand, if you didn't have neurons, you would not feel the pain, or the fact that you are touching something. The neurons in your hand send electrical impulses to your brain through an interconnecting web of neurons, therefore telling you to flinch and remove your hand from the stove.

Neurons form somewhat of a net, coming close to each other, but not quite touching. Although they are both neurons, motor neurons and sensory neurons cannot directly send messages to each other without the help of an interneuron. Because of the network like form around your body, there is never one neuron without another close by. This network is also extremely effective at allowing the nerve impulses to reach the brain quick. As mentioned earlier, nerves are an essential part of the human nervous system, one type of neuron cannot function without either of the other two types. http://ldletkeman.com/blog/wp-content/uploads/2013/02/iStock_000003469801Medium_gfxtra.com_.jpg

=**Ch.5 How do Neurons die and What Happens?**=

Neurons may be the longest living neurons in the human body, but that doesn’t mean they can’t die. During migrations around the body, many, many neurons die. Although it sounds bad, neurons dying during migration is natural. Things really get bad when neurons die because of a disease.

-In Parkinson’s disease, neurons that help with movement die off in an area of the brain that controls body movements. This causes difficulty initiating movement. - In Huntington’s disease, a genetic mutation causes over-production of a neurotransmitter called glutamate, which kills neurons in a section of the brain. As a result, people twist and writhe uncontrollably. - In Alzheimer’s disease, unusual proteins build up in and around neurons in the neocortex and hippocampus, parts of the brain that control memory. When these neurons die, people lose their capacity to remember and their ability to do everyday tasks. Physical damage to the brain and other parts of the central nervous system can also kill or disable neurons. - Blows to the brain, can kill neurons outright or slowly starve them of the oxygen and nutrients they need to survive. - Spinal cord injuries can disrupt communication between the brain and muscles when neurons lose their connection to axons located below the area injured. These neurons may still live, but they lose their ability to communicate.

There are many ways to inflict damage to your neurons, as mentioned earlier when neurons die they usually have some physical effect on the body and of movement of said body. =Conclusion= In the end, I think it is clear that neurons have to be one of the most important cells in the human nervous system. I know, that is a huge claim to make but neurons are one of those cells that simply can't be replace. Without neurons, we would not be able to function in everyday activities like school or sports. Neurons are an essential part of life and they are the only way we can feel.

= Works Cited =

Cardoso, Silvia Helena. “Neurons: Our Internal Galaxy.” Brain & Mind. Henry Holt And Company, 1996. Web. 18 Dec. 2014. .

Coolidge-Stolz,, Elizabeth, M.D. Science Explorer. Boston: Prentice Hall, 2009. Print.

“Neuron.” Science Daily. Science Daily, n.d. Web. 28 Jan. 2015. .

Williams, Frances. Human Body. New York: DK, 1997. Print.