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Neurons can be classified by function or by structure

Neurons can be classified by function or by structure - •...

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Neurons can be classified by function or by structure. Functionally, they fall into three groups:  Sensory neurons  (  afferent  neurons) transmit sensory impulses from the skin and other  sensory organs or from various places within the body toward the central nervous system  (CNS), which consists of the brain and spinal cord.  Motor neurons  (  efferent  neurons) transmit nerve impulses from the CNS toward effectors,  target cells that produce some kind of response. Effectors include muscles, sweat glands, and  many other organs.  Association neurons  (  interneurons ) are located in the CNS and transmit impulses from  sensory neurons to motor neurons. More than 90 percent of the neurons of the body are  association neurons.  Neurons are structurally classified into three groups, as shown in Figure 1: 
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Unformatted text preview: • Multipolar neurons have one axon and several to numerous dendrites. Most neurons are of this type. • Bipolar neurons have one axon and one dendrite. They emerge from opposite sides of the cell body. Bipolar neurons are found only as specialized sensory neurons in the eye, ear, or olfactory organs. • Unipolar neurons have one process of emerging from the cell body that branches, T-fashion, into two processes. Both processes function together as a single axon. Dendrites emerge from one of the terminal ends of the axon. The trigger zone in a unipolar neuron is located at the junction of the axon and dendrites. Unipolar neurons are mostly sensory neurons....
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