Neurons and Their Role in the Nervous System

Table of ContentsView AllTable of ContentsOverviewNeuron StructureFunction of a NeuronHow Neurons CommunicateNeurotransmittersHow Do Neurons Compare to Other Cells

Table of ContentsView All

View All

Table of Contents

Overview

Neuron Structure

Function of a Neuron

How Neurons Communicate

Neurotransmitters

How Do Neurons Compare to Other Cells

Close

A neuron is a nerve cell that is the basic building block of thecentral nervous systemandperipheral nervous system. Neurons are similar to other cells in the human body in a number of ways, but there is one key difference between neurons and other cells. Neurons are specialized in transmitting information throughout the body so we can walk, talk, and process information.

These highly specialized nerve cells are responsible for communicating information in both chemical and electrical forms. There are also several different types of neurons responsible for different tasks in the human body including sensory neurons, motor neurons, and interneurons. They come in different shapes and sizes depending on their specific location and purpose.

In this article, you will learn more about the structure and function of a neuron, how they communicate with each other, and how they are similar and different from other cells in our body.

Structure of a Neuron

There arethree basic parts of a neuron: the cell body, the dendrites, and the axon. However, all neurons vary somewhat in size, shape, and characteristics depending on the function and role of the neuron.

Thecell body(or soma) contains the nucleus and can be likened to a small factory that produces all of the proteins needed to keep the neuron healthy and functioning. The dendrites and axons extend from the cell body.

Dendritesare the extensions that branch off of the cell body and receive signals from other neurons. Some neurons have few dendritic branches, while others are highly branched in order to receive a great deal of information. For example, a single neuron in the brain can create thousands of connections with other neurons with its dendrites.

Theaxonextendsfrom the cell body and is what we commonly refer to as a nerve fiber. The axon transmits information away from the cell body to the nerve ending. Most neurons have only one axon, and it is often covered in a fatty substance called myelin that insulates the nerve fiber and assists with transmitting the signal. Depending on the area of the body, some neurons have very short axons, while others can be quite long.

The longest axon in the human body extends from the bottom of the spine to the big toe and averages a length of approximately three feet!

The nervous system is comprised of sensory neurons, motor neurons, and interneurons, each having a unique function. They also work together to perform complex functions in the human body.

Sensoryneurons(or afferent neurons) carry information from the sensory receptor cells located throughout the body such as the eyes, ears, and skin, to the brain for processing. Sensory neurons help you taste, see, hear, and smell. We can also feel touch, pressure, and temperature.

Interneuronsare responsible for communicating information between sensory and motor neurons via the spinal cord and brain. Complex movements such as walking and talking require the coordination of many muscles. This involves a sensory-motor feedback loop that allows for fine-tuning of gestures in real time. Interneurons also assist withreflexive actions, like pulling your hand off of the hot stove.

How do neurons transmit and receive information? In order for neurons to communicate, they need to transmit information both within the neuron and from one neuron to the next. This process utilizes both electrical signals as well as chemical messengers.

Electrical Signals

Electrical communication begins when the dendrites of a neuron receive a stimulus from an axon of another neuron. This triggers a change in the electrical charge of the cell membrane calleddepolarization, which continues to the cell body. Once the signal has arrived at the beginning of the axon, known as the axon hillock, if the impulse is strong enough, it will travel down the full length of the axon in the form of an electrical signal known as anaction potential.

How Do Neurons Fire?

Chemical Messengers

Once an electrical impulse has reached the end of an axon (axon terminal or nerve ending), the information must be transmitted across thesynaptic gap, the space between the axon terminal of one neuron and the dendrite of the adjoining neuron. The neuron sending the signal is called thepresynapticneuron. The receiving neuron is called thepostsynapticneuron.

How Neurotransmitters Work and What They Do

Neurotransmittersare an essential part of our everyday functioning. While it is not known exactly how many neurotransmitters exist, scientists have identified more than 100 of these chemical messengers.

Neurotransmitters are chemical messengers that are released from the axon terminals to cross the synaptic gap and reach the receptor sites of other neurons. When the neurotransmitters attach to their specific receptor site, like a lock and key, they either excite, inhibit, or modify the action of the postsynaptic neuron depending on what type of neurotransmitter has been received.

Excitatory neurotransmitters stimulate nervous system activity while inhibitory neurotransmitters do the opposite and dampen down nervous system activity. Modulatory neurotransmitters will coordinate the activity of other chemical messengers.

An excitatory neurotransmitter can result in the triggering of a muscle contraction, the release of a hormone from a gland, or simply stimulating another action potential in the next neuron.

The following are just a few of the major neurotransmitters, their known effects, and disorders they are associated with.

Acetylcholine:Associated with memory, learning, and muscle contractions. A lack ofacetylcholinein the brain is associated with Alzheimer’s disease.

Endorphins:Known as our “natural pain reliever,” these chemical messengers are similar to opiate drugs such as morphine but are significantly stronger. The body releasesendorphinsin response to injury, fear, or trauma. Endorphins are associated with emotions, pain perception, sexual response, and maternal behavior.

Dopamine:Known as the “feel good chemical,“dopamineis associated with pleasurable feelings, as well as motivation, mood, attention, and movement.Parkinson’s diseaseis one illness associated with the death of dopamine-producing cells in certain parts of the brain,whereas researchers have found strong links betweenschizophreniaand excessive amounts of dopamine in other parts of the brain.

Serotonin: Plays a role in mood stabilization, learning and memory, blood clotting, digestion, bone health, and sleep.Serotoninhas been implicated in several mental disorders such as depression, anxiety, and obsessive-compulsive disorders. Some of the associated physical health problems are gastrointestinal disorders, high blood pressure, cardiac arrhythmias, and a life-threatening condition calledserotonin syndrome.

The Chemistry of Depression: Neurotransmitters and More

Neurons are similar to other cells in the human body in a variety of ways, but there are also some very unique differences.

Similarities

Differences

11 SourcesVerywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Stifani N.Motor neurons and the generation of spinal motor neuron diversity.Front Cell Neurosci. 2014;8. doi:10.3389/fncel.2014.00293National Institute of Biomedical Imaging and Bioengineering.Neuromuscular junction, how’s that function?Purves D, Augustine GJ, Fitzpatrick D, et al. Neuroscience. 3rd ed. Sunderland: Sinauer Associates; 2008.Ferreira-Vieira TH, Guimaraes IM, Silva FR, Ribeiro FM.Alzheimer’s disease: Targeting the cholinergic system.Curr Neuropharmacol. 2016;14(1):101-115. doi:10.2174/1570159x13666150716165726Pilozzi A, Carro C, Huang X.Roles of β-endorphin in stress, behavior, neuroinflammation, and brain energy metabolism.IJMS. 2020;22(1):338. doi:10.3390/ijms22010338Inagaki TK.Opioids and social connection.Curr Dir Psychol Sci. 2018;27(2):85-90. doi:10.1177/0963721417735531National Institute on Aging.Parkinson’s disease: causes, symptoms, and treatments.Brisch R, Saniotis A, Wolf R, et al.The role of dopamine in schizophrenia from a neurobiological and evolutionary perspective: Old fashioned, but still in vogue.Front Psychiatry.2014;5:47. doi:10.3389/fpsyt.2014.00047De Deurwaerdère P, Di Giovanni G.Serotonin in health and disease.IJMS. 2020;21(10):3500. doi:10.3390%2Fijms21103500Kumar A, Pareek V, Faiq MA, Ghosh SK, Kumari C.Adult neurogenesis in humans: A review of basic concepts, history, current research, and clinical implications.Innov Clin Neurosci. 2019;16(5-6):30-37.Fuchs E, Flügge G.Adult neuroplasticity: More than 40 years of research.Neural Plasticity. 2014;2014:1-10. doi:10.1155/2014/541870Additional ReadingKandel ER, Koester J, Mack S, Siegelbaum S, eds.Principles of Neural Science. Sixth edition. McGraw Hill; 2021.

11 Sources

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Stifani N.Motor neurons and the generation of spinal motor neuron diversity.Front Cell Neurosci. 2014;8. doi:10.3389/fncel.2014.00293National Institute of Biomedical Imaging and Bioengineering.Neuromuscular junction, how’s that function?Purves D, Augustine GJ, Fitzpatrick D, et al. Neuroscience. 3rd ed. Sunderland: Sinauer Associates; 2008.Ferreira-Vieira TH, Guimaraes IM, Silva FR, Ribeiro FM.Alzheimer’s disease: Targeting the cholinergic system.Curr Neuropharmacol. 2016;14(1):101-115. doi:10.2174/1570159x13666150716165726Pilozzi A, Carro C, Huang X.Roles of β-endorphin in stress, behavior, neuroinflammation, and brain energy metabolism.IJMS. 2020;22(1):338. doi:10.3390/ijms22010338Inagaki TK.Opioids and social connection.Curr Dir Psychol Sci. 2018;27(2):85-90. doi:10.1177/0963721417735531National Institute on Aging.Parkinson’s disease: causes, symptoms, and treatments.Brisch R, Saniotis A, Wolf R, et al.The role of dopamine in schizophrenia from a neurobiological and evolutionary perspective: Old fashioned, but still in vogue.Front Psychiatry.2014;5:47. doi:10.3389/fpsyt.2014.00047De Deurwaerdère P, Di Giovanni G.Serotonin in health and disease.IJMS. 2020;21(10):3500. doi:10.3390%2Fijms21103500Kumar A, Pareek V, Faiq MA, Ghosh SK, Kumari C.Adult neurogenesis in humans: A review of basic concepts, history, current research, and clinical implications.Innov Clin Neurosci. 2019;16(5-6):30-37.Fuchs E, Flügge G.Adult neuroplasticity: More than 40 years of research.Neural Plasticity. 2014;2014:1-10. doi:10.1155/2014/541870Additional ReadingKandel ER, Koester J, Mack S, Siegelbaum S, eds.Principles of Neural Science. Sixth edition. McGraw Hill; 2021.

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Stifani N.Motor neurons and the generation of spinal motor neuron diversity.Front Cell Neurosci. 2014;8. doi:10.3389/fncel.2014.00293National Institute of Biomedical Imaging and Bioengineering.Neuromuscular junction, how’s that function?Purves D, Augustine GJ, Fitzpatrick D, et al. Neuroscience. 3rd ed. Sunderland: Sinauer Associates; 2008.Ferreira-Vieira TH, Guimaraes IM, Silva FR, Ribeiro FM.Alzheimer’s disease: Targeting the cholinergic system.Curr Neuropharmacol. 2016;14(1):101-115. doi:10.2174/1570159x13666150716165726Pilozzi A, Carro C, Huang X.Roles of β-endorphin in stress, behavior, neuroinflammation, and brain energy metabolism.IJMS. 2020;22(1):338. doi:10.3390/ijms22010338Inagaki TK.Opioids and social connection.Curr Dir Psychol Sci. 2018;27(2):85-90. doi:10.1177/0963721417735531National Institute on Aging.Parkinson’s disease: causes, symptoms, and treatments.Brisch R, Saniotis A, Wolf R, et al.The role of dopamine in schizophrenia from a neurobiological and evolutionary perspective: Old fashioned, but still in vogue.Front Psychiatry.2014;5:47. doi:10.3389/fpsyt.2014.00047De Deurwaerdère P, Di Giovanni G.Serotonin in health and disease.IJMS. 2020;21(10):3500. doi:10.3390%2Fijms21103500Kumar A, Pareek V, Faiq MA, Ghosh SK, Kumari C.Adult neurogenesis in humans: A review of basic concepts, history, current research, and clinical implications.Innov Clin Neurosci. 2019;16(5-6):30-37.Fuchs E, Flügge G.Adult neuroplasticity: More than 40 years of research.Neural Plasticity. 2014;2014:1-10. doi:10.1155/2014/541870

Stifani N.Motor neurons and the generation of spinal motor neuron diversity.Front Cell Neurosci. 2014;8. doi:10.3389/fncel.2014.00293

National Institute of Biomedical Imaging and Bioengineering.Neuromuscular junction, how’s that function?

Purves D, Augustine GJ, Fitzpatrick D, et al. Neuroscience. 3rd ed. Sunderland: Sinauer Associates; 2008.

Ferreira-Vieira TH, Guimaraes IM, Silva FR, Ribeiro FM.Alzheimer’s disease: Targeting the cholinergic system.Curr Neuropharmacol. 2016;14(1):101-115. doi:10.2174/1570159x13666150716165726

Pilozzi A, Carro C, Huang X.Roles of β-endorphin in stress, behavior, neuroinflammation, and brain energy metabolism.IJMS. 2020;22(1):338. doi:10.3390/ijms22010338

Inagaki TK.Opioids and social connection.Curr Dir Psychol Sci. 2018;27(2):85-90. doi:10.1177/0963721417735531

National Institute on Aging.Parkinson’s disease: causes, symptoms, and treatments.

Brisch R, Saniotis A, Wolf R, et al.The role of dopamine in schizophrenia from a neurobiological and evolutionary perspective: Old fashioned, but still in vogue.Front Psychiatry.2014;5:47. doi:10.3389/fpsyt.2014.00047

De Deurwaerdère P, Di Giovanni G.Serotonin in health and disease.IJMS. 2020;21(10):3500. doi:10.3390%2Fijms21103500

Kumar A, Pareek V, Faiq MA, Ghosh SK, Kumari C.Adult neurogenesis in humans: A review of basic concepts, history, current research, and clinical implications.Innov Clin Neurosci. 2019;16(5-6):30-37.

Fuchs E, Flügge G.Adult neuroplasticity: More than 40 years of research.Neural Plasticity. 2014;2014:1-10. doi:10.1155/2014/541870

Kandel ER, Koester J, Mack S, Siegelbaum S, eds.Principles of Neural Science. Sixth edition. McGraw Hill; 2021.

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