The Nervous System and Neurons

While hormones coordinate slow, widespread responses, the nervous system provides rapid, precise communication. It gathers information, processes it, and drives responses within milliseconds. At its core is a remarkable cell type: the neuron.

Neuron structure

A neuron is specialized to receive, integrate, and transmit electrical signals. Its main parts are:

• Dendrites — branched extensions that receive signals from other neurons.
• Cell body (soma) — contains the nucleus and organelles; integrates incoming signals.
• Axon — a long fiber that carries the signal away from the cell body toward other cells.
• Myelin sheath — a fatty insulating layer, produced by supporting cells, that speeds transmission. Gaps between segments are the nodes of Ranvier.
• Axon terminals — the endings that pass the sign