Notes on Chapter 3

Notes on Chapter 3 - Notes on Chapter 3 Chapter 3 takes us...

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Notes on Chapter 3 Chapter 3 takes us into the wonderful world of Latin names as we learn the parts of the nervous system. I have attempted to bring in function to facilitate this learning. It is important to keep these names straight since we will need them for the rest of the course. In chapter 4 we get into the details of what is a nerve impulse, neurotransmitters and the details of how the nervous system operates. It could be tough going, but we will need that information to explain so many wonderful things about brain and behavior. It will be more fun later. The first distinction we need is between central and peripheral nervous system. The brain and spinal cord are the central nervous system. In both there is what is called gray matter and white matter. The gray matter is tissues which look gray in the preserved sample and are actually areas where nerve cell bodies are tightly packed in. The gray matter in the brain is the cortex, the outer covering of the brain which is only a few millimeters thick. Anatomists distinguish 6 layers with many of the very large pyramidal cells in layer 5. The white matter is composed of a very large number of axons which are white because they are covered with the myelin (fat) layers which are constructed by glial cells. In the brain the neurons conduct nerve impulses down the axons at high speed. In some axons a nerve impulse may speed along at the rate of 100 yards/second! These axons are well covered with glial cells. In most neurons, when the impulse reaches the end of the axons, or the end feet, tiny amounts of neurotransmitters are released into a tiny gap between the end feet and the spine on the dendrite of another neuron. You can see from pictures in the book that a typical large neuron may have hundreds of spines on the dendrites. That chemical either excites or depresses the next neuron in line. This excitation and inhibition are necessary for normal functioning of the brain. In the spinal cord the gray matter comes in the center where nerve cell bodies are tightly concentrated. Surrounding the center are large axon tracts, some of which may run for long distances. The spinal cord is protected by being encases in the backbone, but if the backbone is injured the spinal cord could be pinched or even severed. The latter can lead to paralysis. Neuroscientists are making great efforts in animal research using stem cells to learn how to get these axons to repair themselves. The peripheral nervous system consists of neurons which fun from the spinal cord to the muscles and from sense organs to the spinal cord. These are known as motor neurons or sensory neurons. Motor neurons leave the spinal cord on the ventral side. These neurons are usually multipolar with large cell bodies in the gray matter and axons which travel down the spinal cord, possibly for long distances. Axons entering the spinal cord on the dorsal surface are carrying information from sensory structures on the body. When your doctor taps your leg right below
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This note was uploaded on 02/20/2012 for the course PSY 223 taught by Professor Charleskutscher during the Spring '12 term at Syracuse.

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Notes on Chapter 3 - Notes on Chapter 3 Chapter 3 takes us...

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