View source for Neuron

{{Distinguish|Neutron}}
[[File:Neuron.svg|thumb|right|300px|Diagram of neuron]]

A '''neuron'''<ref name=":0">{{Cite web|title=MeSH Browser|url=https://meshb.nlm.nih.gov/record/ui?ui=D009474|access-date=2026-04-12|website=meshb.nlm.nih.gov}}</ref> (or '''neurone''') is a nerve cell which uses electrical impulses<ref name=g1>{{cite book|first=Ann|last=Fullick|title=Edexcel ICSE Biological Revisions Guide1|year=2011|url=https://archive.org/details/edexceligcsebiol0000full|isbn=9780435046767|page=[https://archive.org/details/edexceligcsebiol0000full/page/40 40]|publisher=Pearson Education Limited }}</ref> to carry out their purpose. Neurons are the basic units of our [[nervous system]]. Their purpose in the nervous system is to receive, transmit, and carry electrical impulses<ref name=":0" /> called [[Action potential|action potentnials]].

Neurons have a cell body (soma or cyton), [[dendrite]]s and an [[axon]].<ref name=g1 /> Dendrites and axons are nerve fibers. There are about 86 billion neurons in the human brain. Almost all brain cells are neurons. The human brain has about 16 billion neurons in the [[cerebral cortex]]. The neurons are supported by [[glial cell]]s and [[astrocyte]]s.<ref>{{Cite web|date=2017-12-07|title=Neurons: What are they and how do they work?|url=https://www.medicalnewstoday.com/articles/320289|access-date=2026-04-12|website=www.medicalnewstoday.com|language=en}}</ref>

Neurons are connected to one another, but they do not actually touch each other. Instead they have tiny gaps called [[synapse]]s. These gaps are [[chemical synapse]]s or [[electrical synapse]]s which pass the signal from one neuron to the next.
== Types of neurons ==

== By connection ==
There are three classes of neurons: motor neurons, sensory neurons and inter neurons.
* Sensory neurons carry information from tissues and organs into the [[central nervous system]]
* Motor neurons transport signals from the [[central nervous system]] to the effector cells
* Interneurons connect neurons within the [[central nervous system]]
== By function ==
*Sensory neurons carry signals from sense organs to the [[spinal cord]] and brain
*Relay neurons carry messages between sensory or motor neurons and the central nervous system
*Motor neurons carry signals from the CNS to muscles, motor neurons are connected to the relay neurons. The signal passes between the neurons via synapses. Synapses are microscopic voids between cells where chemicals are released from the axon terminal of one cell to specialized chemical receptors on the dendrite of the receiving cell
== Cell division ==
Mature neurons never divide: that is the general rule. They do not undergo [[mitosis|cell division]]. In most cases, neurons are generated by special types of [[stem cell]]s. A type of [[glial cell]], called [[astrocyte]]s, have also been seen to turn into neurons. In humans, neurogenesis (the origin of new nerve cells) largely ceases during adulthood {{ndash}} but in two brain areas, the [[hippocampus]] and the [[olfactory bulb]], there is strong evidence for substantial numbers of new neurons.<ref>{{cite news| url=https://www.nytimes.com/1999/10/15/us/brain-may-grow-new-cells-daily.html | work=The New York Times | first=Nicholas | last=Wade | title=Brain may grown new cells daily| date=1999-10-15}}</ref><ref name=r1>{{cite journal|doi=10.1073/pnas.0605605103|title=Stable neuron numbers from cradle to grave|year=2006|last1=Nowakowski|first1=R.S.|journal=Proceedings of the National Academy of Science|volume=103|issue=33|pages=12219–12220 |pmid=16894140|pmc=1567859|bibcode=2006PNAS..10312219N|doi-access=free | issn=0027-8424 }}</ref><ref name="r1" /><ref>Blinkov S.M. & Glezer I.I. 1968. ''The human brain in figures and tables: a quantitative handbook''. New York, Plenum.</ref><ref>Roth, Gerhard 2013. ''The long evolution of brains and minds''. Springer, Dordrecht.</ref>

== Neuron Media ==
<gallery widths='160px' heights='100%' mode='traditional' caption=''>
File:Gyrus Dentatus 40x.jpg|[[Golgi stain|Golgi-stained]] neurons in human [[hippocampal]] tissue

File:SUM 110913 Cort Neurons 2.5d in vitro 488 Phalloidin no perm 4 cmle-2.png|Actin filaments in a mouse cortical neuron in culture

File:GFPneuron.png|Image of pyramidal neurons in mouse [[cerebral cortex]] expressing [[green fluorescent protein]]. The red staining indicates [[GABA]]ergic interneurons.

File:Structural_classification_of_neurons_by_polarity_hariadhi.svg|Different kinds of neurons

File:Neurotransmitters.jpg|Synaptic vesicles containing neurotransmitters

File:Chemical synapse schema cropped.jpg|A signal propagating down an axon to the cell body and dendrites of the next cell

File:Neuro Muscular Junction.png|A neuromuscular junction (or myoneural junction) is a chemical synapse formed by the contact between a motor neuron and a muscle fiber. It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.*Labels from top right: myelin sheath, mitochondria, 

File:All-or-none law en.svg|As long as the stimulus reaches the threshold, the full response will be given. A larger stimulus does not result in a larger response, and vice versa.{{Rp|31}}

File:Golgi Hippocampus.jpg|Drawing by Camillo Golgi of a [[hippocampus]] stained using the [[silver nitrate]] method

File:Purkinje cell by Cajal.png|Drawing of a Purkinje cell in the [[cerebellar cortex]] done by [[Santiago Ramón y Cajal]], demonstrating the ability of Golgi's staining method to reveal fine detail
</gallery>
== Related pages ==
*[[Artificial neural network]]
*[[Brain cell]]
*[[Neurotransmitter]]
== References ==
{{reflist}}
== Other websites ==
* [http://www.eurekalert.org/pub_releases/2007-07/uoc--bcp070307.php Fibrinogen found to inhibit EGFR in neuronal cells] {{Webarchive|url=https://web.archive.org/web/20210413061840/http://www.eurekalert.org/pub_releases/2007-07/uoc--bcp070307.php |date=2021-04-13 }} ''Blood clotting protein may inhibit spinal cord regeneration'' 
* [http://ccdb.ucsd.edu/CCDB/index.shtml Cell Centered Database] {{Webarchive|url=https://web.archive.org/web/20070813131941/https://ccdb.ucsd.edu/CCDB/index.shtml |date=2007-08-13 }} UC San Diego images of neurons.
* [http://brainmaps.org High resolution neuroanatomical images of primate and non-primate brains] {{Webarchive|url=https://web.archive.org/web/20190621124504/http://brainmaps.org/ |date=2019-06-21 }}.

[[Category:Anatomy of the nervous system]]
[[Category:Cells]]