Dendrites are extensions of neurons, that receive chemical signals, in the form of neurotransmitters, from neighboring neurons at synapses. These incoming signals are processed and when they reach a certain threshold, the neuron generates electrical impulses, known as action potentials. This electric impulse propagates along the axon to transmit a signal to other neurons. Dendrites help in the transmission and processing of information within the nervous system.
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Dendrite Definition
Dendrites are the branched extensions of neurons that receive and process incoming signals from neighbouring neurons, enabling communication within the nervous system.
What is Dendrites?
Dendrites are the protoplasmic projections of the neuron and they receive the cellular signals from the other neurons through synaptic junctions. They are the first to receive information from the neighbouring neurons and are covered in tiny protrusions called dendritic spines, which increase their surface area for connecting with other neurons. The direction of flow of signals within a neuron is unidirectional. The signals travels from dendrites to the cell body and then along the axon to communicate with other neurons.
These signals are transmitted from one neuron to another in the form of chemical neurotransmitters across synapses, the junctions between neurons. Dendrites process these incoming signals, add them up within the neuron and generate an electrical impulse known as an action potential.
Diagram of the Dendrites
The diagram of the Dendrites is as follows:
Structure of Dendrites
The dendrites receive, process, and transfers the incoming signal to the axon of neuron. The structure of the dendrite is as follows:
- Dendrites are projections that extends from the cell body of a neuron towards axon.
- Each dendrite is about 2 µm in length and mostly 5 – 7 dendrites are present in one neuron cell.
- A complex interwoven structure is formed by them close to the neuron called the dendritic tree.
- It is covered in small, bulbous protrusions called dendritic spines, which increase their surface area for receiving signals.
- Dendrites are present in various shapes and sizes, depending on the type of neuron and the function it perform within the nervous system.
- Dendritic spines changes in shape and size, this is known as synaptic plasticity, which is required for learning and memory.
- Dendrites act as the receptive surfaces of neurons, that receives chemical signals from other neurons at synaptic junction.
- Dendrites contain various cytoplasmic components, like cytoskeletal structures and organelles such as Golgi apparatus, ribosomes, and smooth endoplasmic reticulum. These components support the protein synthesis required for dendritic function during signal transmission.
Types of Dendrites
Dendrites can be divided into various types depending upon the dendrite morphology and dendrite branching. The types of dendrites are as follows:
- Adendritic Dendrite: As the name suggests there are no branches of dendrites,
- Spindled Dendrite: From two opposite ends of the neuronal cell body, two branches of dendrites are formed Example: Bipolar neurons.
- Spherical Dendrite: All around the neuronal cell body dendritic branches are present thereby giving a spherical appearance to the dendritic tree, Example: Cerebellar granule cells.
- Laminar Dendrite: From the neuronal cell body, the dendritic branches extends in a planar fashion. Example: Retinal ganglion cells.
- Cylindrical Dendrite: From the neuronal cell body, the dendritic branches radiates in all directions in a disc-like manner. Example: Pallidal neurons.
- Conical Dendrites: From the neuronal cell body, the dendritic branches protrude in a conical fashion. Example: Pyramidal cells.
- Fanned Dendrite: From the neuronal cell body, the dendritic branches protrude in a flat fan-like shape. Example: Purkinje cells.
Function of Dendrites
Function of dendrites are as follows:
- Dendrites act as a primary receptor surfaces of a neuron. They receive chemical signals in the form of neurotransmitters released at synapses by neighboring neurons.
- Dendrites process the incoming signals by adding up the excitatory and inhibitory inputs they receive and generate an electrical impulse called an action potential.
- The weak signals are amplified by it that enables the neuron to determine and respond to specific information.
- It processes and filters incoming information, allowing neurons to differentiate between different types of signals.
- Dendritic spines are present on dendrites which can change their shape and size, a process known as synaptic plasticity. This helps in learning and keeping memory about things.
FAQs on Dendrites
1. What are dendrites?
Answer:
Dendrites are the branching extensions of neurons that receive and process incoming signals from other neurons in the nervous system.
2. What is the function of dendrites in neurons?
Answer:
Dendrites receive, integrate, and process incoming signals or information from neighbouring neurons and transmit information within the nervous system.
3. What is the relationship between dendrites and axons?
Answer:
Dendrites are first one to receive the signals and they transmit them toward the cell body, while axons transmit signals away from the cell body to communicate with other neurons.
4. Where are dendrites located?
Answer:
Dendrites are present on the neurons and radiates from the cell body of the neuron. They branch out to receive signals from other neurons at synapses.
5. How do dendrites receive signals?
Answer:
Dendrites receive signals in the form of chemical neurotransmitters released by neighboring neurons at synapses. These neurotransmitters bind to receptors on the dendritic spines.