Unipolar vs. bipolar vs. multipolar neurons: How do they compare? 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Neurons use electrical impulses and chemical signals to transmit information between the central nervous system (CNS) and the rest of the body. There are different types of neurons, and scientists distinguish each type by its number of components and its structure. Multipolar neurons can transfer the most information between cells, and they are the most common form of neuron in the human nervous system. This article takes a closer look at unipolar, bipolar, and multipolar neurons. What is a neuron Share on Pinterestkoto_feja/Getty ImagesA neuron is a nerve cell that passes information around the body through electrical impulses and chemical signals. The cell structure enables neurons to pass on information, as they have long extensions from the cell body for transmitting and receiving information. The components of the neuron work together to facilitate nerve function. The three main parts of a neuron are:Cell body, or soma: The cell body has a nucleus that contains the cell’s genetic material and controls the cell’s activities.Axon: This part, which looks like a long tail, transmits signals from the cell.Dendrite: This part, which looks like the branches of a tree, receives signals for the cell. Neurons send information to each other by transmitting chemical signals called neurotransmitters across special junctions called synapses. These synapses are present at the tips of dendrites. There are several types of neurons with different structures. Some neurons contain multiple dendrites, while others have none. The types include:unipolar neuronspseudounipolar neuronsbipolar neuronsmultipolar neuronsanaxonic neurons What are unipolar neurons A unipolar neuron only has one nerve process extending from the cell body: an axon that extends into dendrites. Unipolar neurons only occur in invertebrates, such as flies, and are not present in humans. In invertebrates, unipolar neurons play a role in the glands and muscles. Although the human body does not contain unipolar neurons, pseudounipolar neurons are present. A pseudounipolar neuron is a cell that only occurs as a sensory neuron. In a pseudounipolar neuron, the nerve process extending from the cell body splits into two branches or axons. As a result, the neuron has two separate axons that independently divide into dendrites at the ends. This form is similar to that of a bipolar neuron. What are bipolar neurons A bipolar neuron has two distinct structures extending from the cell body. One is an axon, and the other is a dendrite. Bipolar neurons are uncommon and only occur in a few specific areas within the body. These include:the olfactory epithelium, which is nerve tissue that runs along the nasal cavity and plays a role in smellthe retina, a thin layer of tissue at the back of the eye that receives light signalscertain nerves within the ear What are multipolar neurons Multipolar neurons are the most common type of neurons in the human body. They are present throughout a person’s CNS, including the brain and associated nerves in the autonomic nervous system. A multipolar neuron has the highest number of structures extending from the cell body. There is only one axon, but each cell has many dendrites, making it easier for the neuron to exchange information. Similarities Unipolar, bipolar, and multipolar neurons have some similar characteristics. They all feature long structures extending from the cell body. Additionally, they all have the main components of the cell body, axon, and dendrite. Despite occurring in different areas within the body, the neurons play a similar role, as they are responsible for passing information between the brain and the CNS. Differences The number and structure of components differ among unipolar, bipolar, and multipolar neurons. For example, the dendrites only occur at the tips of the axon in unipolar neurons, but multiple dendrites stem from the cell body of a multipolar neuron. The structure of bipolar neurons is similar to that of pseudounipolar neurons in that two distinct structures stem from the cell body. However, instead of starting as one extension that splits into two, the structures grow independently out of the cell body. The structure of a multipolar neuron is different again, as more than two structures extend from the cell body. The table below summarizes the differences between unipolar, bipolar, and multipolar neurons.UnipolarBipolarMultipolarOccurrence in the human bodynonerarecommonLocation—ear, nose, eyethroughout the CNSStructureone extension from the cell body, containing one axon with dendrites at its tiptwo extensions from the cell body, including one axon and one dendritemultiple extensions from the cell body, including one axon and many dendrites Frequently asked questions Below, we answer some common questions about unipolar, bipolar, and multipolar neurons. Is a sensory neuron unipolar bipolar or multipolar Most of the sensory neurons in a human body are pseudounipolar. However, unipolar and bipolar types can also be sensory neurons. What anatomical characteristics determine whether a neuron is unipolar bipolar or multipolar The structural components of a neuron determine whether it is unipolar, bipolar, or multipolar. These components are called axons, which transmit information, and dendrites, which receive information.A unipolar neuron has one axon which extends into dendrites, though this splits into two parts in pseudounipolar neurons.A bipolar neuron has two completely independent structures extending from the cell body, one of which is an axon and the other a dendrite.A multipolar neuron only has one axon extending from the cell body, but multiple dendrites grow out of it, making transmitting information easier. Are unipolar neurons present in humans No, humans do not have unipolar neurons. However, they do have pseudounipolar neurons. Summary Neurons are nerve cells that transfer information around the body, and some types form part of the CNS. The three main types of neurons are unipolar, bipolar, and multipolar. Other forms, including pseudounipolar and anaxonic neurons, also exist. Three major components make up a neuron. These are the cell body, axons, and dendrites. The arrangement of these components determines the type of neuron. Unipolar neurons are the simplest form, with one axon extending from the cell body. The axon splits up into dendrites at the ends. Unipolar neurons do not occur in humans. Bipolar neurons have one axon and one dendrite extending from the cell body. Their presence in humans is limited, but they play an important role within the ears, nose, and eyes. Multipolar neurons are the most complex and commonly occurring type of neuron within the human body. Each neuron has one axon but multiple dendrites extending from the cell body. Multipolar neurons occur throughout the CNS. Last medically reviewed on July 29, 2022Biology / BiochemistryNeurology / Neuroscience 7 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.35.2: Neurons and glial cells - neurons. (2022).https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/35%3A_The_Nervous_System/35.02%3A_Neurons_and_Glial_Cells_-_NeuronsBrain basics: The life and death of a neuron. (2022).https://www.ninds.nih.gov/health-information/patient-caregiver-education/brain-basics-life-and-death-neuronLudwig, P. E., et al. (2021). Neuroanatomy, neurons.https://www.ncbi.nlm.nih.gov/books/NBK441977/Multipolar neuron. (n.d.).https://www.sciencedirect.com/topics/neuroscience/multipolar-neuronNeurons and glial cells. (n.d.).https://oertx.highered.texas.gov/courseware/lesson/1789/overviewRolls, M. M., et al. (2015). Neuronal polarity: An evolutionary perspective.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4334146/Unipolar neuron. (n.d.).https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/unipolar-neuronFEEDBACK:Medically reviewed by William C Lloyd III, MD, FACS — By Helen Millar on July 29, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageWhat are the similarities and differences between DMDD and bipolar disorder?Medically reviewed by Akilah Reynolds, PhD Learn about the symptoms and treatments of disruptive mood dysregulation disorder (DMDD) and bipolar disorder (BD) and how the two conditions compare.READ MOREHow do genetic differences affect the risk of bipolar disorder? 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