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Axon Function, Meaning & Types | What is an Axon?

Keta Bhakta, John Williams
  • Author
    Keta Bhakta

    Keta Bhakta graduated from University of Minnesota with a B.S. in Neuroscience and then with a D.D.S. as a dentist. She has tutored many students in various math and science subjects. She began working as a professor at the University of Minnesota School of Dentistry in 2013.

  • Instructor
    John Williams
In this lesson, learn what is an axon and the functions performed by axons. Diagrams are used to show the various parts of an axon such as the axon terminal. Updated: 07/29/2021

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What Is An Axon?

The human body is made up of millions and millions of cells. There are many different types of cells that comprise the body and perform specific and important functions in order to achieve the function of that particular tissue, organ, and organ system. One such cell located primarily within the nervous system, i.e. the brain and the spinal cord, is called a neuron or a nerve cell. A neuron is the most elementary unit of function within the nervous system and it works by relaying messages to other neurons, muscle cells, cardiac cells, glandular cells, etc., in the form of electrical impulses. There are three main types of neurons in the human body that further perform specific and crucial functions: sensory, motor, and interneurons or relay neurons.

The characteristic or feature that is common to these three different types of nerve cells is their structure, which is comprised of dendrites, soma (cell body with nucleus), and axon. The dendrite receives input from other cells while the cell body contains major organelles such as the nucleus. The axon directs messages away from the neuron towards other cells. The focus of this article will be on this crucial component within a neuron called an axon.

An axon is a cable that transmits messages away from the cell body or soma towards the dendrites of other neurons or the sensory receptors of other types of cells to impact them directly. Each axon typically has multiple branches coming off the main branch of the axon known as axon collaterals, which then split into terminal branches. And each axon terminal has an output receptor at the end of it known as a synaptic terminal. The synaptic terminal transmits chemical messages and release neurotransmitters onto other cells. The space between the synaptic terminal and the input receptor of the next cell is known as a synapse. Electrical signals are used within the neuron itself in the form of action potentials.

The main branch of axons are also typically coated with a fatty tissue known as a myelin sheath, which greatly increases the speed of conductance of the electrical impulse or message down the axon by acting as an insulator. An axon can be thinner than the width of the human hair. Axons can vary in length anywhere from 1 mm in the brain to over 1 meter in the spinal cord.

Neurotransmitter release

Neurotransmitter release

Axon Functions

An axon performs a very crucial function within a neuron. It directs electrical impulses or action potentials away from the cell body or soma of a neuron towards another cell (another neuron, muscle cell, etc.). While a neuron can have many dendrites to receive impulses, there is typically only one axon per neuron. An axon from a motor neuron can have a synapse onto a muscle cell which would either signal the muscle fiber to fire and move a muscle or relax and cease any movement, depending on which kind of neurotransmitter or electrical impulse is transmitted. Similarly, an axon from a sensory neuron can have a synapse with a sensory receptor in the fingertip which would eventually allow the brain to sense a specific touch or temperature being perceived at that fingertip.

Axonal transport refers to the transference of various substances through a nerve cell, and it can be divided into anterograde or retrograde transport. Anterograde transport means that materials such as organelles like mitochondria or neurotransmitters are moved from the cell body toward the axon. Meanwhile, retrograde transport moves waste products away from axon terminals towards the cell body for processing. Just like how a regular cell contains a cytoplasm, an axon within a neuron contains an axoplasm. There are transport protein scaffolding materials known as microtubules and neurofilaments arranged in the axoplasm of the neuron that allows both anterograde and retrograde transport of materials in both directions within an axon. Anterograde transport uses kinesin protein to aid with the transport while retrograde transport uses dynein.

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  • 0:00 Introduction To Axons
  • 0:48 Structures Of Axons
  • 1:42 Communication Via Axons
  • 2:42 Lesson Summary
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Axon Structure

There are many important structures within an axon as listed below:

Neuron structure

Neuron structure

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Frequently Asked Questions

What are axons in the nervous system?

Axons are part of a neuron that relay action potentials within a neuron and transform them into chemical messages to then be transmitted to other cells.

What do terminal branches do?

The terminal branches of an axon change electrical impulses or action potentials within a neuron into chemical messages in the form of neurotransmitters. These neurotransmitters are released from terminal branches into synapses to relay messages to other neurons or other types of cells like muscle cells.

What is the function of the axon and dendrite?

The dendrite receives input messages from a neuron and other cells, whereas an axon relays output messages away from the neuron towards other cells.

Where is the axon of a neuron?

The axon is located at the distal end of a neuron and relay output messages. The dendrites are located at the proximal end and they receive information from other neurons and cells.

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