Webster, Douglas B. Department of Otorhinolaryngology and Biocommunication, Louisiana State University Medical Center, Baton Rouge, Louisiana.
Last reviewed:January 2019
Show previous versions
- Links to Primary Literature
- Additional Readings
A nerve cell; the functional unit of the nervous system. A neuron is a specialized, basic nerve cell that transmits and receives information, in the form of electrical impulses, throughout the body. It is the fundamental component of the nervous system. Structurally, the neuron is made up of a cell body (soma) and one or more long processes—a single axon and dendrites (see illustration). The cell body contains the nucleus and usual cytoplasmic organelles with an exceptionally large amount of rough endoplasmic reticulum, called the Nissl substance (or Nissl body) in the neuron. The longest cell process is the axon, which is capable of transmitting propagated nerve impulses. There may be none, one, or many dendrites composing part of a neuron. If there is no dendrite, it is a unipolar neuron; with one dendrite, it is a bipolar neuron; if there is more than one dendrite, it is a multipolar neuron. The dendrites are shorter and more branched than the axon. Dorsal-root spinal ganglia (groups of nerve cell bodies) and most cranial nerve ganglia have unusual pseudounipolar neurons. In pseudounipolar neurons, which are always sensory, a single process leaves the soma and then bifurcates, sending a long peripheral process to skin, muscle, or viscera and sending a central process into the spinal cord or brain. Both processes can conduct nerve impulses. In most neurons, only the axon propagates nerve impulses; the dendrites and somas are also irritable, but they do not propagate nerve impulses. See also: Autonomic nervous system; Brain; Central nervous system; Endoplasmic reticulum; Ganglion; Nerve; Nervous system (invertebrate); Nervous system (vertebrate); Neurobiology; Neuronal replacement therapy; Spinal cord
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 9000 highly qualified scientists and 43 Nobel Prize winners.
MORE THAN 8500 articles and Research Reviews covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information