Neuron
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A neuron is a nerve cell, the basic signaling unit of the nervous system, which receives information and passes it on as electrical and chemical signals.
Also: nerve cell, neurone, neurons
Definition
What is a neuron?
A neuron, or nerve cell, is a cell built to carry information. A typical neuron has three parts: a cell body, or soma, that holds the nucleus; branching dendrites that collect incoming signals; and a single axon that carries signals away to other cells. The human brain holds roughly 86 billion neurons, which rely on glial cells to insulate, nourish and protect them.
Neurons communicate with a mix of electricity and chemistry. Inputs arriving at the dendrites and cell body shift the voltage across the cell membrane, and if the shift at the axon hillock reaches threshold, the neuron fires an action potential that races down the axon. At the axon terminals, that signal triggers the release of neurotransmitters across a synapse onto the next neuron, a muscle cell or a gland.
Neurons are grouped by shape, as multipolar (one axon and many dendrites, the most common kind), bipolar or pseudounipolar, and by job: sensory neurons bring information in, motor neurons carry commands out, and interneurons link the two. Bundles of axons form nerves outside the brain and spinal cord and tracts within them.
Word parts
Where does the word “neuron” come from?
- neur-
- nerve; originally sinew or cordGreek neuron
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Terms that go with it
- AxonAn axon is the single long projection of a neuron that carries electrical impulses away from the cell body toward other neurons, muscles or glands.
- DendriteA dendrite is one of the short, branching extensions of a neuron that receive signals from other cells and carry them toward the cell body.
- SynapseA synapse is the junction where a neuron passes a signal to another cell, usually by releasing a neurotransmitter across a narrow gap.
- Action potentialAn action potential is a brief, all-or-none reversal of the voltage across a nerve or muscle cell membrane that travels along the cell as a signal.
- MyelinMyelin is the fatty, layered sheath that glial cells wrap around many axons, insulating them so nerve impulses travel faster and more efficiently.
- NeurotransmitterA neurotransmitter is a chemical messenger that a neuron releases at a synapse to excite or inhibit a target neuron, muscle cell or gland cell.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Anatomy and Physiology 2e, 12.2 Nervous Tissue
- OpenStax Biology 2e, 35.1 Neurons and Glial Cells
- NCI Dictionary of Cancer Terms: neuron
- NCBI MeSH: Neurons
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