What is a neuron and what are its three main parts?

A neuron is a nerve cell that transmits electrical and chemical signals throughout the nervous system. Its three main parts are the cell body, or soma, which contains the nucleus and maintains the cell's life functions; the dendrites, which are branching extensions that receive incoming signals from other neurons; and the axon, a long fiber that carries the electrical impulse away from the cell body toward other neurons, muscles, or glands. Many axons are covered by a myelin sheath, a fatty insulating layer that speeds up signal transmission.