Nerve cell (neuron), illustration. Neurons are responsible for passing information around the central nervous system (CNS) and from the CNS to the rest of the body. Each nerve cell comprises a body (top) surrounded by numerous extensions called dendrites. Dendrites collect information from other nerve cells or from sensory cells. Each neuron also has one process called an axon (down centre), which passes information to other nerve cells, or to effector cells such as muscle fibres. The axon appears segmented as it is surrounded by a myelin sheath (blue) that contains gaps, called nodes of Ranvier. The myelin insulates the axon, allowing signals to be transmitted more quickly.