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Article: Nervous Systems
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- Biology
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CopyrightCOPYRIGHT 2002 The Gale Group Inc. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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Nervous Systems
The nervous system is a network of nerve cells and, in most animals, a brain. In vertebrates, it also includes a spinal cord. The primary cell type found in the nervous system is the
neuron
, which has a cell body, containing the
nucleus
, and long extensions to carry information from one part of the body to another.
The nervous system has two primary functions that are critical in maintaining the life of the organism. First, sensory receptors allow the organism to monitor its external environment and detect changes that occur (for example, an increase in temperature). The nervous system then activates structures such as muscles and glands, which permit the organism to ...