Central nervous system is one of a chief system of our body. It controls our body in different ways. It has nerves that transmit signals from central nervous system to the parts of the body. The basic unit of the central nervous system is neuron. It is defined as a specialized cell that transmits nerve impulses; it is also called a nerve cell. Axons and Dendrites are the part of the neuron. Axon is the long threadlike part of a neuron along which the nerve impulse travel from the cell body to other parts. Whereas, a dendrite is a short part extension of a neuron by which impulses are received from the center and are further transmitted to the cell body or axon of a neuron. In simple words, axons are the output of neuron and dendrites are the input of the neuron. Dendrites receive information from the external or internal environment and transmit information to the cell body and axon of a neuron. Dendrites are multiple in number and short while axon is single but varies in length.
What are Axon?
Axon is derived from a Greek word which means axis. Axon is the output of the neuron. Its function is to transfer information from the body of the neuron to the other part of the body or the another neuron. Axons have a uniform diameter and a smooth surface. Only one axon per cell is present. Axon begins as axon hillock, which is a swelling at the junction between soma and axon of a neuron. It has many sodium (Na) channels in them which help in the generation of action potential throughout neuron. Axons are usually long, and they end as axon terminal on the other neuron or part of the body. Note that axon has branches only at its terminal. Axons also have many vesicles in them in which different neurotransmitter are present. It also has calcium (Ca) channels in its membrane. Axons do not contain Nissl’s granules. It also has no ribosome. Axons are of two types: myelinated axons and unmyelinated axons. Myelinated axons have myelin sheath around them. Myelin sheath act as an insulator and also forms Nodes of Ranvier which help in salutatory conduction. Unmyelinated axons lack myelin sheath around them. Axons end via a synapse, if axon of one neuron is connected to the axon of another neuron, it is called axoaxonal. If axon of one neuron is connected to the dendrite of another neuron, it is called axodendritic. And if axon of one neuron is connected directly to the soma, it is known as axosomatic. Axons also form neuromuscular junctions at muscle by directly ending on them.
What are Dendrites?
Dendrite is derived from a Greek word which means tree. Dendrite is the input of the neuron. Its function is to receive information from the center and transmit it to the cell body of the neuron. Axons have a nonuniform diameter and a rough surface. There are many dendrites per cell. Dendrite receives information from the surroundings and transmits it forward to the cell body and axon of a neuron. Dendrites are numerous in a single neuron and are relatively shorter as compared to axons; it also has many branches that are present only at its origin. If dendrite of one neuron is connected to the axon of the other neuron, it is known as axodendritic. And if dendrites are connected to the dendrite of another neuron, it is known as dendrodendritic. Dendrites contain Nissl’s granules and have ribosomes. They have no myelin sheath around them and have branches near the cell body of the neuron.
Axon vs. Dendrite
- Axon takes information or impulse away from the cell body, whereas Dendrites bring information or impulse to the cell body of the neuron.
- Axons are long and single per cell while dendrites are short and multiple per cell.
- Axons do not have ribosomes, although they may have myelin sheath while dendrites have ribosomes but no myelin sheath around them.
- Axons have branches far away from the cell body, and these branches are present at the terminal point or axon terminal of a neuron and contrary to this dendrites have branches near the cell body, and these branches are present at the origin of the neuron.
- Axons do not contain Nissl’s granules, on the other hand, dendrites have Nissl’s granules.
- Axons have vesicles that contain neurotransmitter in them, but dendrite has no vesicles.