A cell that is specialized to conduct nerve impulses; SYN. neuron.
Or neuron; Elongated cell, the basic functional unit of the nervous system that transmits information rapidly between different parts of the body. Each nerve cell has a cell body, containing the nucleus, from which trail processes called dendrites, responsible for receiving incoming signals. The unit of information is the nerve impulse, a traveling wave of chemical and electrical changes involving the membrane of the nerve cell. The cells longest process, the axon, carries impulses away from the cell body.
The impulse involves the passage of sodium and potassium ions across the nerve-cell membrane. Sequential changes in the permeability of the membrane to positive sodium (Na+) ions and potassium (K+) ions produce electrical signals called action potentials. Impulses are received by the cell body and passed, as a pulse of electric charge, along the axon. The axon terminates at the synapse, a specialized area closely linked to the next cell (which may be another nerve cell or a specialized effector cell such as a muscle). On reaching the synapse, the impulse releases a chemical neurotransmitter, which diffuses across to the neighboring cell and there stimulates another impulse or the action of the effector cell.
Nerve impulses travel quicklyin humans, they may reach speeds of 160 m/525 ft per second.
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