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Classification of Neurons

Classification of Neurons - axonal endings of one neuron...

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Classification of Neurons Classified structurally and functionally. Structurally they are grouped according to the number of processes extending from the body. Three major neuron groups: multipolar: 3 or more processes bipolar: 2 processes - an axon and a dendrite extend from opposite sides unipolar: single process; very short and divides t-like. Functional classification according to the direction in which the nerve impulse travels relative to the CNS. Sensory or afferent: transmit impulses from sensory receptors in the skin or internal organs toward the CNS. Motor or efferent: carry impulses away from the CNS to the effecter organs (muscles, glands). Virtually all sensory neurons of the body are unipolar and their cell bodies are located in sensory ganglia outside the CNS. Motor neurons are multipolar, and their cell bodies are located in the CNS. The Synapse The operation of the nervous system depends on the flow of information through circuits consisting of chains of neurons connected by synapses. Most synapses occur between the
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Unformatted text preview: axonal endings of one neuron and the dendrites or the cell bodies of other neurons. Less common are the synapses between axons, between dendrites, or between dendrites and cell bodies. The neuron conducting impulses toward the synapse is called the preslynaptic neuron (information sender). The neuron that transmits the electrical activity away from the synapse is the postsynaptic neuron (information recipient). Most neurons function as both presynaptic and postsynaptic neurons, receiving information from some neurons and dispatching it to others. A typical neuron has thousands of axonal terminals making synapses and is stimulated by an equal number of other neurons. In the body periphery, the postsynaptic cell may be either another neuron or an effecter cell. Synapses between neurons and muscle cells are neuromuscular junctions. Synapses between neurons and gland cells are neuroglandular junctions. There are two varieties of synapses: electrical and chemical....
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