The key difference between axon and dendrites is the function of these two types of cytoplasmic extensions of the neuron. Axon passes nerve impulses away from the cell body while dendrites pass nerve impulses towards the cell body.
Neurons are of three main types; motor neuron, sensory neuron and interneuron. All neurons are composed of a cell body that does all the functions and cytoplasmic extensions that can either be axons or dendrites. Therefore, the functions of axon and dendrites occur upon the direction in which the nerve impulse is transmitted.
CONTENTS
1. Overview and Key Difference
2. What are Axons
3. What are Dendrites
4. Similarities Between Axons and Dendrites
5. Side by Side Comparison – Axons vs Dendrites in Tabular Form
6. Summary
What are Axons?
Axon is a long cytoplasmic extension arising from the cell body of the neuron. It passes nerve impulses away from the cell body to effectors located in muscles and glands. Each neuron has a single axon, although an axon may also branch to stimulate some cells. A myelin sheath encases axons, and there are Schwann cells located on the myelin sheath. Axons can further be myelinated or non-myelinated. Myelination increases the speed of nerve impulse transmission. Therefore it acts as an insulator for the nerve impulse transmission
Figure 01: Axon
Several myelin sheaths wrap around a single axon, and in between, there are gaps giving rise to nodes of Ranvier. Axons contain neurofibrils but not Nissl’s granules.
What are Dendrites?
Dendrites are the short cytoplasmic extensions arising from the cell body and enable neurons to receive nerve impulses simultaneously from different receptors located all over the body. Motor neurons and interneurons usually possess highly branched dendrites.
Figure 02: Dendrites
Certain neurons have numerous extensions arising from their dendrites called dendritic spines, and that increases the surface area available to receive nerve impulses. Dendrites do not contain neurofibrils, but Nissl’s granules are present.
What are the Similarities Between Axons and Dendrites?
- Both Axons and Dendrites are parts of a neuron.
- Axons and Dendrites arise from the cell body.
- Both Axons and Dendrites are involved in transporting nerve impulses.
What is the Difference Between Axons and Dendrites?
Axons vs Dendrites |
|
| The axon is the long extension of the neuron that passes nerve impulses away from the cell body. | The dendrites are the short extensions that pass nerve impulses towards the cell body. |
| Structure | |
| Axons are a long thin process of uniform thickness and smoothness. | Dendrites are short processes, thickness diminishes, and the branches are studded with spiny projections. |
| Number per Cell Body | |
| One neuron has one axon. | One neuron has multiple projections of dendrites. |
| Neurofibrils | |
| Neurofibrils are present in axons. | Neurofibrils are absent in dendrites. |
| Presence of Nissl’s Granules | |
| Nissl’s granules are absent in axons. | Nissl’s granules are present in axons. |
| Ribosomes | |
| Ribosomes are absent in axons. | Ribosomes are present in axons. |
| Myelin Insulation | |
| Myelin sheath may be or may not be present in axons. | Myelin sheath is absent in dendrites. |
| Branching Points | |
| Branching points of axons branch away from the cell body. | Branching points of dendrites branch closer to the cell body. |
Summary – Axons vs Dendrites
Axons and dendrites are important structures found in a neuron. The neuron is the main structural and functional unit of the nervous system. The axons involve in taking nerve impulses away from the cell body. These signals are passed on to effector cells such as muscles and glands. Dendrites are involved in transmitting nerve impulses towards the cell body. The nerve signals received by sensory organs are passed on to the cell body. This is the difference between axons and dendrites.
Image Courtesy:
1.’Blausen 0657 MultipolarNeuron’By BruceBlaus – Own work, (CC BY 3.0) via Commons Wikimedia
2.’Dendrite (PSF)’By Pearson Scott Foresman (Public Domain) via Commons Wikimedia