Dendrite refers to the ‘Trees‘ in Greek, so these are the branched small extension of the nerve cell. Axon refers to the ‘axis‘ in Greek, so axon is the long slender like protrusion of the neuron or nerve cell.
Secondly, dendrite receives messages or information or electrochemical impulses from the external environment or other neurons, so they work as the input for the neuron. The role of the axon is to send messages or any information or electrochemical impulses to the external environment or other neurons. So they are the output for the neuron.
Neurons or nerve cells or neurones are the most basic and essential part of the nervous system and brain. These cells are specialized in sending and receiving the motor commands and sensory inputs, respectively to and from the outer environment. In short, they relay and transforms the electrical signals at every action done by our body.
Above that, nerve cells are responsible for our thought process, so they define or represents our way of thinking, that how we react and take actions in each and every step.
Likewise, a tree, a neuron or nerve cell has three main parts: an axon, dendrites and a cell body or soma, which can be referred as roots, branches and trunk of a tree. In this article, we will be going through the difference between the dendrites and axons and also going through their description.
Content: Dendrite Vs Axon
|Basis for Comparison||Dendrite||Axon|
|Meaning||Dendrite is an expansion of a nerve cell, and these are short branched development, numerously present in a cell.||Axon is the projection in the long slender form of a neuron or nerve cell that are single per cell.|
|Other features||There are many dendrites in a nerve cell.||There is only one axon per neuron or nerve cell.|
|Dendrites are very short.||Axon is very long.|
|They have all over branches, like the branches of a tree.||Axons are branched at the end side.|
|Dendrites have their origin from the nerve cell.||Axon originates from the axon hillock, which is the conical projection.
|1. There are numerous spines on dendrites that provide the surface for other nerve cells to synapse on or to form a neuronal junction (the platform of transmission of an electric nerve between two neurons). |
2. These synapses receive information from an outer environment or other cells, so dendrites become postsynaptic.
|Axons are presynaptic because at the end they have terminal boutons or synaptic knobs where synapse is located.|
|The junction between dendrites that synapse on axons is called axodendritic.||The synaptic knobs of the axons hold neurotransmitter that contains numerous vesicles. They also have channels like 'Ca2+ channels' in their membrane.
|The junction between dendrites that synapse on other dendrites is known as dendrodendritic.||The synaptic cleft (space between another cell and terminal boutons) has a thickness of about 20nm.|
|Dendrites bear Nissl's granules.||Axons do not have Nissl's granules, but neurofibrils are present.|
|Ribosomes are present in dendrites, having tapering ends due to which their diameter goes on decreasing.||Axons do not have ribosomes, and they have a uniform diameter.|
|Functions||Receive messages or signals or nerve impulses from the external environment or other nerve cells.||Axon sends or transfer signals or nerve impulses to the outer environment or other neurons.|
Definition of Dendrite
The outgrowth or the extended part of the nerve cell or neuron is called a dendrite. As said above that dendrites are spread or branched like the shape of a tree, and there are many dendrites in one nerve cell. These branches help and support in receiving signals from the other synapses.
The main function of the dendrite is to receive the nerve impulse or signals coming to form other synapses and forward it to the cell body. Dendrite signals or electrochemical messages are in the form of neurotransmitters, sent by other neurons through the special receptor present on the exterior of dendrites.
Dendrites are non-myelinated, due to short-projections and tapering ends. Dendrite was discovered by the ‘Wilhelm His (Mall 1905), he was Swiss anatomist in the year 1889.
Definition of Axon
The nerve fibre or axon is the critical part of a nerve cell (neuron) that carries signals or information in the form of nerve impulses from the cell body to the outer environment. As said, the nerve cell has only one axon, which long slender projection and connects it with other muscle, gland cells and other neurons.
The length of axons are quite long, and some may be as long as the spinal cord to the toe. In the vertebrates, axons are enclosed within a myelin sheath and result in an increase or quick transmission of impulse; like some large axons transmit impulse at the speed of 90 metres (300 feet) per second. Presence of this myelin (fatty substance) is responsible for white matter of the brain.
The axon is the long cable that elongates from the nerve cell or neuron of brain to other body parts, and these are even thinner than the hair and work in transmitting the electrical impulses from the nerve cell to other neurons.
The axons have side branches known as axon collaterals, these help in sending the same information to other neurons. These collaterals are extended in the same way as the roots of the tree, which has sub roots that splits as the terminal branches; and each of their tip has synaptic terminal.
The communication point for the neurons are the synapses, that is the junction between the axon terminals and cell bodies or dendrites of the other cell. At this point, the electrical signals coming through axons are converted into chemical signals, with the help of neurotransmitter and then again converted back into electric signals and transfer to other neurons.
Key Differences Between Dendrite and Axon
Following points are essential one to differentiate the two most important part of the nerve cell, which are dendrite and axon:
- As per the ‘Greek’ word ‘dendrite‘ refers to a ‘tree’ and so dendrite is an expansion of a nerve cell, these are short branched development, numerously present in a cell. On the other hand, ‘axon‘ refers to ‘axis’ in ‘Greek’, so axon is the projection in the long slender form of a neuron or nerve cell, that are single per cell.
- There are many dendrites in a nerve cell and are short in length; while there is only one axon per neuron or nerve cell, but their length is long.
- Branches of dendrites are spread all over, just like the branches of a tree, whereas axons are branched at the end side known as axons collateral.
- Dendrites have their origin from the nerve cell; although axon originates from the axon hillock, which is the conical projection.
- There are numerous spines on dendrites that provide the surface for other nerve cells to synapse on or to form a neuronal junction (the platform of transmission of an electric nerve between two neurons). These synapses receive information to form an outer environment or other cells, so dendrites become postsynaptic. On the other hand, axons are presynaptic, because at the end they have terminal boutons or synaptic knobs where synapse is located.
- The junction between dendrites that synapse on axons is called axodendritic; The synaptic knobs of the axons holds neurotransmitter, that contains numerous vesicles. They also have channels like ‘Ca2+ channels’ in their membrane.
- The junction between dendrites that synapse on other dendrites is known as dendrodendritic; The synaptic cleft (space between another cell and terminal boutons) has a thickness of about 20nm.
- Dendrites bear Nissl’s granules and are non-myelinated, although axons do not have Nissl’s granules, they are myelinated
- Functions of the dendrite are to receive messages or signals or nerve impulses from the external environment or other nerve cells, whereas axon sends or transfer signals or nerve impulses to the outer environment or other neurons.
- Axons and dendrites are the extended or outgrowth of the nerve cell or neuron, but play a critical role for the nerve cell.
- Both are helpful in the transmission of nerve impulse or signals.
- Both have neurofibrils and are branched structure.
So, from the above content, we can say that dendrite is the afferent while axon is the efferent components of the nerve impulses and work in sending and receiving electric impulse. As we know dendrites have a shorter length than axons, although axons are myelinated dendrites are not, this enhances the speed of sending the signal to other cells.