Neurons and How They Work in Your Body

Neurons are information messaging cells within the central nervous system (CNS) and peripheral nervous system (PNS). They make it possible for your body to manage processes that you don't think about, like digestion, as well as decisions typically within your conscious control, like walking and talking.

There are three main categories of neurons: motor neurons, sensory neurons, and interneurons. Each is responsible for a different aspect of perception and movement, as well as essential brain functions like learning and decision-making.

Structure

Most neurons have three parts. These include:

• The cell body: It contains the nucleus of the neuron, where genetic information is stored. It also includes the cytoplasm, the fluid that houses the majority of cellular material within the neuron.
• The axon: This long, narrow connecting line snakes away from the cell body to send electrical impulses to other neurons. An axon looks like a long tail with branches to send these impulses.
  
• Dendrites: Dendrites also look like tree branches that extend from the neuron cell body, but they receive messages from a neuron. Each dendrite's end allows for cells to communicate.
  

Glial Cells

Neurons rely on another type of cell called glial cells. Glial cells are sometimes referred to as "nerve glue" because they provide connectivity between neurons to allow for the movement of information. They aid in the transport of nutrients, hormones, and neurotransmitters.

Function

The CNS includes the brain and spinal cord, while the PNS includes neurons throughout the rest of the body. Neurons use electrical impulses, chemical signals, and neurotransmitters to communicate information throughout the CNS and PNS.

Neurotransmitters travel across a small area between the axon of one neuron and the dendrite of another so that cells can communicate with each other immediately and constantly. This tiny space, which allows for information exchange, is called a synapse.

Neurons complete this task using a process called "action potential." Action potential is the quick flow of electrical voltage from the neuron down the axon. This voltage allows information to be transmitted from neuron to neuron all over the body.

This information exchange enables us to think, talk, feel, move, and do everything else that our bodies are capable of.

Types

There are three main types of neurons:

• Motor neurons connect the brain to muscles throughout the body. They transmit electrical impulses containing information to skeletal and smooth muscles, controlling all of our body movement.
• Sensory neurons are neurons that let us feel sensations. If you burn your hand, sensory neurons will send chemical and electrical impulses back through the nervous system to let your brain know that you feel pain in your hand.
• Interneurons are the nerve cells that connect motor neurons to other motor neurons and sensory neurons to other sensory neurons.

Motor Neurons

Motor neurons transmit electrical impulses and information from the CNS to muscles in the body.

There are two motor neuron subtypes:

• Upper motor neurons: Upper motor neurons are located in the brain and communicate with the lower motor neurons.
• Lower motor neurons: These neurons receive messages from upper motor neurons and communicate them to the lower portion of the body.

Lower motor neurons pool together in the spinal cord to control specific muscle groups. Motor neurons control movement throughout the body, including breathing, speaking, swallowing, and digestive movements like peristalsis, which moves food through the digestive tract.

Neurons are located in the brain and spinal cord, which are organs of the CNS. Neurons are also located throughout the rest of the body in the PNS.

Sensory Neurons

Sensory neurons allow us to feel sensations. For example, if you stub your toe, sensory neurons will send chemical and electrical impulses back through the nervous system to tell your brain that you feel pain.

Sensory neurons can be activated physically, such as feeling touch, or chemically, such as tasting a piece of cake. All five of our senses—sound, sight, touch, smell, and taste—are impacted by sensory neurons.

Some sensory neurons have specialized endings, such as free nerve endings or encapsulated receptors, to detect various stimuli, including touch, pressure, temperature, pain, and chemical signals. They then communicate this information about the world to the CNS for processing.

Interneurons

Interneurons are nerve cells that connect between motor neurons and sensory neurons. For example, if your sensory neurons detect that you have touched a hot stove, interneurons communicate that to your motor neurons so that you quickly move your hand away.

Interneurons can also send information to and from other interneurons. They can be quite different from one another in terms of their shape and physiology. They can be classified into two types:

• Local interneurons: These form circuits with nearby interneurons to analyze small pieces of information. Local interneurons have short axons.
• Relay interneurons: These connect the messages of neurons in various parts of the brain. Relay interneurons have long axons and involve connecting neurons between different regions of the brain.

Interneurons and Depression

Research has shown that drugs that inhibit a type of interneuron called gamma-aminobutyric acid (GABA) can have a rapid antidepressant effect. This suggests that interneurons play a role in depression, and drugs like ketamine that inhibit GABA and other interneurons might be a key to future depression treatments.

Summary

Neurons carry signals throughout the central and peripheral nervous systems. They send electrical impulses and chemical signals to and from the brain.

Most neurons have three parts: a cell body, which contains the nucleus and cytoplasm; an axon, which transmits information away from the nucleus; and dendrites, which receive messages from other neurons.

The main types of neurons include motor neurons, which transmit information to our muscles, sensory neurons, which transmit information to enable our senses, and interneurons, which aid transmission between motor and sensory neurons.

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

1. Faber DS, Pereda AE. Two forms of electrical transmission between neurons. Front Mol Neurosci. 2018;11:427. doi:10.3389/fnmol.2018.00427
2. National Institute of Neurological Disorders and Stroke. Brain basics: the life and death of a neuron.
3. Argente-Arizón P, Guerra-Cantera S, Garcia-Segura LM, Argente J, Chowen JA. Glial cells and energy balance. J Mol Endocrinol. 2017;58(1):R59-R71. doi:10.1530/JME-16-0182
4. National Institute of Neurological Disorders and Stroke. Motor neuron diseases.
5. D’Elia KP, Hameedy H, Goldblatt D, et al. Determinants of motor neuron functional subtypes important for locomotor speed. Cell Rep. 2023;42(9):113049. doi:10.1016/j.celrep.2023.113049
6. Donnelly CR, Chen O, Ji RR. How do sensory neurons sense danger signals? Trends Neurosci. 2020;43(10):822-838. doi:10.1016/j.tins.2020.07.008
7. Purves D, Augustine GJ, Fitzpatrick D, et al. Cutaneous and subcutaneous somatic sensory receptors. Neuroscience.
8. Fishell G, Kepecs A. Interneuron types as attractors and controllers. Annu Rev Neurosci. 2020;43:1-30. doi:10.1146/annurev-neuro-070918-050421
9. Zavvarian MM, Hong J, Fehlings MG. The functional role of spinal interneurons following traumatic spinal cord injury. Front Cell Neurosci. 2020;14:127. doi:10.3389/fncel.2020.00127
10. Fogaça MV, Wu M, Li C, Li XY, Picciotto MR, Duman RS. Inhibition of GABA interneurons in the mPFC is sufficient and necessary for rapid antidepressant responses. Mol Psychiatry. 2021;26(7):3277-3291. doi:10.1038/s41380-020-00916-y

By Sarah Jividen, RN
Jividen is a freelance healthcare journalist. She has over a decade of direct patient care experience working as a registered nurse specializing in neurotrauma, stroke, and the emergency room.

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