Saltatory conduction is the rapid transmission of nerve impulses alongmyelinated axons. In myelinated neurons, the axon is covered with a fatty insulating layer called myelin, which is interrupted at gaps known as nodes of Ranvier. During saltatory conduction, the electrical impulse "jumps" from one node to the next, greatly increasing the speed of signal transmission. Unmyelinated axons conduct impulses more slowly because the signal must travel continuously along the entire membrane. Dendrites receive signals rather than transmit them over long distances, and muscle cells do not conduct nerve impulses in this manner. The NEX Science exam commonly tests nervous system physiology, particularly mechanisms that improve conduction speed, making myelinated axons the correct answer.
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