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• Types of nervous systems
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• Neuromuscular diseases

The nervous system is a collection of cells, tissues, and organs through which an organism receives information from its surroundings and then directs the organism as to how to respond to that information. As an example, imagine that a child accidentally touches a very hot piece of metal. The cells in the child's hand that detect heat send a message to the child's brain. The brain receives and analyzes that message and sends back a message to the child's hand. The message tells the muscles of the hand to pull itself away from the heat.

The basic unit of the nervous system is a neuron. A neuron is a nerve cell capable of passing messages from one end to the other. In the example above, the "hot" message was...