nerve fiber
Definition
Noun: A long, slender projection of a nerve cell (neuron) that conducts electrical impulses. It is the primary structure for transmitting signals within the nervous system.
Usage
The term "nerve fiber" refers specifically to the axon of a neuron, which is the part that carries nerve impulses away from the cell body. It is a core anatomical and physiological concept in biology and medicine.
Examples
- Damage to a single nerve fiber can disrupt the signal to a specific muscle.
- The sciatic nerve contains the longest nerve fibers in the human body.
- Researchers are studying how to regenerate nerve fibers after spinal cord injuries.
Advanced Usage
- Myelinated vs. Unmyelinated Nerve Fibers: This distinction is critical. Myelinated fibers are insulated by a fatty sheath (myelin), which allows signals to travel faster. Unmyelinated fibers lack this sheath and conduct impulses more slowly.
- Sensory and Motor Nerve Fibers: Nerve fibers are classified by function. Sensory (afferent) fibers carry signals the central nervous system (e.g., touch, pain). Motor (efferent) fibers carry signals the central nervous system to muscles or glands.
Variants and Related Words
- Axon (n): A synonym for "nerve fiber"; the neuronal process that conducts impulses.
- Neuron (n): The entire nerve cell, including the cell body, dendrites, and axon (nerve fiber).
- Nerve (n): A bundled group of many nerve fibers (axons) along with supportive tissue.
- Neurofibril (n): A fine filament within the nerve fiber/axon.
Synonyms
- Axon
- Neurite (a general term for any projection from a neuron cell body, which includes axons and dendrites, though often used interchangeably with axon in some contexts).
Notes on Meaning
The term "nerve fiber" is sometimes used more loosely to refer to any slender process of a neuron. However, in precise anatomical and physiological contexts, it is synonymous with the axon. It is distinct from a "nerve," which is a macroscopic structure containing many fibers.
Noun
-
a threadlike extension of a nerve cell
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