Glossary
neuron
A neuron is a nerve cell that receives, carries and passes on information as an electrical impulse, and its working parts are the dendrites, the cell body and the axon.
A neuron is the cell that carries information in the nervous system as an electrical impulse. It has three functional parts. Dendrites branch off the cell body and receive signals from other cells. The cell body, or soma, holds the nucleus and does the cell's metabolic work. The axon is the single long process that carries the impulse away, and at its far end it branches into terminals. Many axons are wrapped in myelin, a fatty insulation laid down by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system, with gaps called nodes of Ranvier where the impulse is regenerated. At the terminals the neuron releases neurotransmitters across a synapse to the next cell. Neurons are classified by direction: sensory (afferent) neurons carry information toward the central nervous system, motor (efferent) neurons carry commands away from it, and interneurons connect the two inside the brain and spinal cord. A neuron does not divide, and most of them are present for life.
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Related terms
- synapse — A synapse is the junction where a neuron passes its signal to another cell, across a narrow gap, by releasing a neurotransmitter.
- myelin sheath — The myelin sheath is fatty insulation wrapped around some axons that speeds the impulse by letting it jump between the nodes of Ranvier.
- reflex arc — A reflex arc is the pathway a reflex travels — receptor, sensory neuron, a synapse in the CNS, motor neuron and effector — without waiting for the brain.
Source: The anatomy and physiology guide in this course, whose organ and tissue descriptions follow the US National Cancer Institute's SEER Training Modules and MedlinePlus consumer health pages. Both are US federal government material, not subject to copyright in the United States. The definition above is written for this course in our own words. (SEER Training Modules accessed 2026-10-26; definition written 2026-10-27)