What Is A Neuron? Diagrams, Types, Function, And More - Healthline

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An Easy Guide to Neuron Anatomy with Diagrams

Medically reviewed by Heidi Moawad, M.D. — Written by Carly Vandergriendt and Rachael Zimlich, RN, BSN — Updated on August 1, 2025

Anatomy
Types
Function
Research
Takeaway

Neurons, also known as nerve cells, send and receive signals throughout your nervous system. While neurons have a lot in common with other types of cells, they’re structurally and functionally unique.

Specialized projections called axons allow neurons to transmit electrical and chemical signals to other neurons. Neurons can also receive these signals via rootlike extensions known as dendrites.

The human brain houses about 86 billion neurons.

The creation of new nerve cells is called neurogenesis. This process isn’t well understood. It happens throughout life, according to research from 2019, but it’s known to be most active during prenatal development and during early childhood.

As researchers gain insight into both neurons and neurogenesis, many are also working to uncover links to neurodegenerative diseases like Alzheimer’s and Parkinson’s.

Parts of a neuron

Neurons vary in size, shape, and structure depending on their role and location. However, nearly all neurons have three essential parts: a cell body, an axon, and dendrites.

Cell body

Also known as a soma, the cell body is the core section of the neuron. The cell’s nucleus contains genetic information. The cell’s body maintains the neuron’s structure, and provides energy to drive activities.

Like other cell bodies, a neuron’s soma contains a nucleus and specialized organelles. It’s enclosed by a membrane that both protects it and allows it to interact with its immediate surroundings.

Axon

An axon is a long, tail-like structure. It joins the cell body at a specialized junction called the axon hillock. Many axons are insulated with a fatty substance called myelin. Myelin helps axons to conduct an electrical signal.

Neurons usually have one main axon.

Dendrites

Dendrites are fibrous roots that branch out from the cell body. Like antennae, dendrites receive and process signals from the axons of other neurons. Neurons can have more than one set of dendrites, known as dendritic trees.

How many they have generally depends on their role. For instance, Purkinje cells are a special type of neuron found in a part of the brain called the cerebellum. These cells have highly developed dendritic trees which allow them to receive thousands of signals.

Types of neurons

Neurons vary in structure, function, and genetic makeup. Given the sheer number of neurons, there are thousands of different types, much like there are thousands of species of living organisms on Earth.

However, there are five major neuron forms. Each combines several elements of the basic neuron shape.

Multipolar neurons: These neurons have a single axon and symmetrical dendrites that extend from it. This is the most common form of neuron in the central nervous system.
Unipolar neurons: Usually only found in invertebrate species, these neurons have a single axon.
Bipolar neurons: Bipolar neurons have two extensions extending from the cell body. At the end of one side is the axon, and the dendrites are on the other side. These types of neurons are mostly found in the retina of the eye. But they can also be found in parts of the nervous system that help the nose and ear function.
Pyramidal neurons: These neurons have one axon but several dendrites to form a pyramid type shape. These are the largest neuron cells and are mostly found in the cerebral cortex. The cerebral cortex is the part of the brain responsible for conscious thoughts.
Purkinje neurons: Purkinje neurons have multiple dendrites that fan out from the cell body. These neurons are inhibitory neurons, meaning they release neurotransmitters that keep other neurons from firing.

In terms of function, scientists classify neurons into three broad types: sensory, motor, and interneurons.

Sensory neurons

Sensory neurons help you:

taste
smell
hear
see
feel things around you

Sensory neurons are triggered by physical and chemical inputs from your environment. Sound, touch, heat, and light are physical inputs. Smell and taste are chemical inputs.

For example, stepping on hot sand activates sensory neurons in the soles of your feet. Those neurons send a message to your brain through a neuronal pathway, which makes you aware of the heat.

Motor neurons

Motor neurons play a role in movement, including voluntary and involuntary movements. These neurons allow the brain and spinal cord to communicate with muscles, organs, and glands all over the body.

There are two types of motor neurons: lower and upper. Lower motor neurons carry signals from the spinal cord to the smooth muscles and skeletal muscles. Upper motor neurons carry signals between and within your brain and spinal cord.

When you eat, for instance, lower motor neurons in the nerves of your mouth, throat, and digestive system send signals to the smooth muscles in your esophagus, stomach, and intestines. These muscles contract, which allows food to move through your digestive tract.

Interneurons

Interneurons are neural intermediaries found in your brain and spinal cord. They’re the most common type of neuron. They pass signals from sensory neurons and other interneurons to motor neurons and other interneurons. Often, they form complex circuits that help you to react to external stimuli.

For instance, when you touch something sharp like a cactus, sensory neurons in your fingertips send a signal to interneurons in your spinal cord. Some interneurons pass the signal on to motor neurons in your hand, which allows you to move your hand away. Other interneurons send a signal to the pain center in your brain, and you experience pain.

How do neurons work?

Neurons send signals using action potentials. An action potential is a shift in the neuron’s potential electric energy caused by the flow of charged particles in and out of the membrane of the neuron. When an action potential is generated, it’s carried along the axon to a presynaptic ending.

Action potentials can trigger both chemical and electrical messages. Synapses are locations where neurons can pass these electrical and chemical messages between them. Synapses are made up of a presynaptic ending, a synaptic cleft, and a postsynaptic ending.

Chemical synapses

In a chemical synapse, the neuron releases chemical messengers called neurotransmitters. These molecules cross the synaptic cleft and bind to receptors in the postsynaptic ending of a dendrite.

Neurotransmitters can trigger a response in the postsynaptic neuron, causing it to generate an action potential of its own. Alternatively, they can prevent activity in the postsynaptic neuron. In that case, the postsynaptic neuron doesn’t generate an action potential.

Electrical synapses

Nerve endings have a space between them called a synapse, also called a gap junction. Chemicals or electrical signals communicate by releasing neurotransmitters or electrolytes into the synapse. This gap is made up of ion channels that help transmit a positive electrical signal.

Research

While research has advanced our understanding of neurons in the last century, there’s still much we don’t understand. More research is needed to better understand what really happens.

There is still hope, though, that neural stem cells might be used to make new neurons. Neural stem cells may produce new neurons, according to the National Institute of Neurological Disorders and Stroke. But researchers are still trying to figure out the best way to use these stem cells to produce specific types of neurons in the laboratory setting.

If this can be done, these nerve cells could theoretically be created to replace those that are lost through age, damage, and disease.

Ongoing clinical trials

Many clinical trials are currently underway to test the use of newly created neural cells. For example, a 2019 study used fluorescent probes to observe real-time activity in the nerve cells of mice. This technology could be used to help map brain activity, uncover the problems that lead to neurological disorders, and advance the field of artificial intelligence.

Educational resources

Want to see how much you learned today? Use the resources below to quiz yourself (or your students) on the anatomy and different types of neurons.

Anatomy of a Neuron study guide
Anatomy of a Neuron quiz
Types of Neurons study guide
Types of Neurons quiz

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Quiz yourself on the anatomy of a neuron!

Takeaway

Nervous system cells are called neurons. They have three distinct parts, including a cell body, axon, and dendrites. These parts help them to send and receive chemical and electrical signals.

While there are billions of neurons and thousands of varieties of neurons, they can be classified into three basic groups based on function. These are motor neurons, sensory neurons, and interneurons.

There’s still a lot we don’t know about neurons and the role they play in the development of certain brain conditions. But many research projects and clinical trials are underway to try and find those answers.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Brain basics: The life and death of a neuron. (2025).https://www.ninds.nih.gov/health-information/public-education/brain-basics/brain-basics-life-and-death-neuron
Catani M. (2022). Neuroanatomical bases of human behavior.https://www.sciencedirect.com/science/article/pii/B9780128196410001675
Hale J. (2020). How many neurons are in the human brain? A journey to find the answer.https://centerforinquiry.org/blog/how-many-neurons-are-in-the-human-brain-a-journey-to-find-the-answer/
Kumar A, et al. (2019). Adult neurogenesis in humans: A review of basic concepts, history, current research, and clinical implications.https://pmc.ncbi.nlm.nih.gov/articles/PMC6659986/
Neurons -- Multipolar neurons. (n.d.).http://vanat.cvm.umn.edu/neurLab1/neuron.html
Piatkevich KD, et al. (2019). Population imaging of neural activity in awake behaving mice.https://www.nature.com/articles/s41586-019-1641-1
Scientists build largest maps to date of cells in human brain. (2023).https://www.nih.gov/news-events/nih-research-matters/scientists-build-largest-maps-date-cells-human-brain
Sorrells SF, et al. (2018). Human hippocampal neurogenesis drops sharply in children to undetectable levels in adults.https://www.nature.com/articles/nature25975
Steinberg G. (2025). A safety and tolerability study of neural stem cells (NR1) in subjects with chronic ischemic subcortical stroke (ISS).https://clinicaltrials.gov/ct2/show/NCT04631406
Thomason ME, et al. (2021). Development of brain networks in utero: Relevance for common neural disorders.https://pmc.ncbi.nlm.nih.gov/articles/PMC7808399/
Types of neurons (n.d.).https://qbi.uq.edu.au/brain/brain-anatomy/types-neurons
Van der Heijden ME, et al. (2022). Interactions between Purkinje cells and granule cells coordinate the development of functional cerebellar circuits.https://pmc.ncbi.nlm.nih.gov/articles/PMC7736359/
What is a neuron? (n.d.).https://qbi.uq.edu.au/brain/brain-anatomy/what-neuron

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Medically reviewed by Heidi Moawad, M.D. — Written by Carly Vandergriendt and Rachael Zimlich, RN, BSN — Updated on August 1, 2025

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