nerve cell
Meaning of nerve cell: Every thought, movement and sensation depends on these cells passing electrical and chemical signals to one another.
Definition of nerve cell
A nerve cell is the basic working unit of the nervous system, built to carry information as brief electrical signals. It has a cell body, branching dendrites that collect incoming messages, and a long fiber called an axon that passes signals on. Chemical messengers carry each signal across the narrow gap between one nerve cell and the next.
What are the parts of a nerve cell?
Each part has one job, and the shape of the cell follows from those jobs.
| Part | What it does |
|---|---|
| Cell body | Holds the nucleus and keeps the cell alive |
| Dendrites | Short branches that receive signals from other cells |
| Axon | A single long fiber that carries the signal away |
| Myelin sheath | A fatty wrapping that makes the signal travel faster |
| Axon terminal | Releases chemical messengers onto the next cell |
How does a signal travel?
Inside the cell the signal is electrical. A wave of charge sweeps down the axon, always in one direction, and it either fires at full strength or not at all. At the end of the axon the electrical signal stops. The cell releases a chemical messenger into the tiny gap, called a synapse, and that chemical lands on the next cell and starts the process again. A single nerve is a bundle of many such fibers wrapped together, in the way a cable holds many wires.
Do nerve cells grow back?
It depends on where they are. Fibers running to the arms, legs and skin can regrow after injury, slowly and not always accurately. Nerve cells in the brain and spinal cord largely cannot, which is why damage there tends to be permanent. The optic nerve behaves like brain tissue in this respect rather than like a limb nerve, despite its name.
Also known as
Used in a sentence
The biopsy showed a marked loss of nerve cells in the affected region of the cortex.
Good to know
Nerve cell and neuron name the same structure. Glial cells are also part of nervous tissue but support nerve cells rather than carry signals themselves.
Word origin
Where “nerve cell” comes from
The alternative name neuron comes from the Greek neuron, meaning sinew or cord, later applied to nerves.