Data Bases • Custom Term Papers • Free Term Papers • Free Research Papers • Free Essays • Free Book Reports • Plagiarism? Links • Top 100 Term Paper Sites • Top 25 Essay Sites • Top 50 Essay Sites • Search 97,000 Papers @ DirectEssays.com • Search 101,000 Papers @ ExampleEssays.com • Search 90,000 Papers @ MegaEssays.com Free Essays • Term Paper Sites • Chuck III's Free Essays • Free College Essays • TermPaperSites.com • My Term Papers • Get Free Essays • Essay World • Planet Papers	Search Lots of Essays Back to Subjects - Psychology Nervous system Nervous system The nervous system of the human body is responsible for sending, receiving and processing nerve impulses. It controls the actions and sensations of all the parts of the human body as well as your thoughts, emotions and memories. The nervous system is a “speedy electrochemical communication system of all the nerve cells of the peripheral and central nervous system”. The most basic and important part in the usefulness of the Nervous System is the Neuron. The neuron is the functional unit of the Nervous System consisting of 100 billion neurons in 1 human brain alone. While they vary in size and shape, all neurons have 3 identical parts that enable them to function. The first part of a neuron, the Cell Body, contains the nucleus, mitochondria and other organelles which are all critical elements of a neurons character. Second, Dendrites, are the area of the neuron that receive information from other cells and transmit the message to the cell body, while the last element known as the Axon conducts messages away from the cell. These 3 specific areas are an important asset to the function of each neuron. Each containing the previously listed areas of the neuron, there are three separate types of neurons occurring in the Nervous System. One being the Sensory neurons, which carry incoming messages from sensory receptors to the Central NS. Another, Motor neurons, transmit the outgoing messages from the Central NS to the body’s muscles and glands. Although our nervous system has millions of sensory and motor neurons, it consists of billions of interneurons. Interneurons are found only in the Central NS where they connect neuron to neuron to provide communication throughout each cell. Together these multiple systems help to make up one section of the Nervous System known as the Peripheral Nervous System. The Peripheral NS consists of the “sensory and motor neurons that connect the Central NS to the rest of the body”. It consists of two components, the Somatic nervous system, which controls the movements of our skeletal muscles and the Automatic nervous system, which controls the glands and muscles of our internal organs. The automatic nervous system is a dual system that has influence over the heartbeat, digestion, and glandular activity. These two systems which make up the automatic NS are known as Sympathetic and Parasympathetic NS. The Sympathetic NS stimulates the body for defensive performance. If someone should become frightened or infuriated about something, the sympathetic NS will accelerate the bodies heartbeat, raise blood sugar and dilate your arteries to prepare you for action. When someone feels stressed, their Parasympathetic NS produces opposite effects such as decreasing the heartbeat and lowering blood sugar in an attempt to relax the body. On a daily basis, these two systems work together so that the body can remain in a stable interior condition. The Peripheral Nervous System lays the groundwork for the most important area of the Nervous System, the Central NS. Consisting of the brain and Spinal cord, the Central NS is often compared to a powerful computer since its purpose is so complex. The Central NS enables humans to think, feel and act, AND without this area, other parts of the human body would be nonexistent. The gray area of the Spinal cord consists mostly cell bodies and dendrtites, while the surrounding white matter contains bundles of interneural axons. These Axons allow the Spinal cord to function in the Nervous Sysytem by transmitting ascending impulses to the brain and descending impulses from the brain to the rest of the body. The Spinal cord is also involved in reflexes that do not immediately involve the brain. For example, a spinal reflex pathway is composed of one sensory neuron and one motor neuron, which exchange information through an interneuron. This pathway allows for the “pain reflex”. Therefore, if you were to touch a flame on a candle or a gas stove, neural activity energized by the heat would move to the sensory neurons and then into the interneurons and finally into your Spinal cord. The interneurons react by stimulating motor neurons into the muscles in your arm. Because the simple pain reflex pathway runs through the Spinal cord and out, your hand jerks away from the flame before your brain receives and responds to the message. This leads us to the role the brain plays throughout the Nervous System and the entire body. In the Nervous System, the brain receives and interprets information as well as decides responses. These reactions occur in thousands of neural networks located in the brain. To better clarify these networks and other functions the brain provides, Betty Ann will explain. Bibliography: Word Count: 772
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