Neurons
Neurons or nerve cells are the primary components or building blocks of the nervous system. About 86 billion neurons in the nervous system work together to keep the body functioning properly. They serve as the brain’s information processing and transmitting hubs and are highly specialised cells. Numerous neurons make up a nerve.
They come in a variety of sizes and qualities despite having a recognisable elongated shape, depending on their location and the functions they perform. They are similar to other cells in many ways, but they are very different from other cells in terms of structure and function. All neurons are primarily made up of three parts: axons, cell bodies, or somas, and dendrites. In addition to the three primary parts, there are additional. Axon terminal and synapse are also present at the neurons end in addition to the three main components.
Dendrites
They are specialised add-ons that look like tree branches. Dendrites contribute to a greater surface area being made available for connections with neighbouring neurons and subsequently for receiving incoming signals from them. Dendrites can be very short and tiny in certain neurons or quite long in others. While some neurons only have one dendrite, the majority of neurons have many.
Functions
Obtaining chemical input from neurons and other cellselectrical impulses from the chemical signalscarrying electrical signals to the cell body, the following component of the neuron,
Soma or the Cell Body
It is the centre of the neuron, analogous to the nucleus and other cellular organelles in a cell. The cell body, which is also the biggest component of a neuron, is protected from its immediate surroundings and enables interaction with the outside world by a cell membrane. They affix to every dendrite, integrating every signal as a result. The cell body, which also houses the DNA that makes up a neuron’s genetic makeup, is where all of the cell’s metabolic processes take place.
Axons
They are tiny, elongated membrane strands that resemble fibres in nerve cells. From one neuron cell body to the terminal of the following neuron, axons extend. They are the longest portion of the neuron and can range in length from as little as 0.1 millimetres to more than 3 feet. The rate of transmission of nerve signals increases with the axon’s diameter. Sometimes a single axon will have many branches to allow for better simultaneous communication with many target neurons.
Axon components:
- The portion of the axon that is still connected to the cell body or soma is known as a “axon hillock.”
- The layer of fatty acids known as the myelin sheath, which surrounds the axon, is created by specialised cells known as Schwann cells.
- Nodes of Ranvier – The spaces in the myelin sheath’s discontinuous path down the axon.
Functions
By modifying the electrical potential of the cell membrane known as the action potential, axons assist in receiving signals from other neurons and transmitting the outflow of the message to the neighbouring linked neurons as well as to other muscles and glands. Similar to an insulated electric line, the myelin sheath protects the axon by isolating it to prevent shock. Additionally, the myelin sheath accelerates the rate at which signals pass through the axon.Nodes of Ranvier permit ion diffusion into and out of the neuron, maintaining the neuron’s electrical potential.
Other structures (which are not basic parts) are present at the junctions between the neurons and assist in creating functional links or connections between them in addition to all the major parts that have thus far been described in a neuron:
Axon terminal and synapse: The Connecting Synapse of a Neuron
The terminal branches of the axon, also known as the synaptic bouton or terminal button, are found at the very tip of the neuron. They are the furthest from the soma and contain synaptic vesicles, which are specialised structures that house chemical messengers called neurotransmitters.
The minuscule space or cleft between two adjacent neurons is known as a synapse or synaptic cleft. It is created between the dendrites of the next neurons and the axon terminal of the preceding neuron.
Functions
Exocytosis is the process by which neurotransmitters are released from one neuron to the adjacent linked neurons through particular transport vesicles known as synaptic vesicles. one neuron’s synaptic vesicles for transferring nerve impulses to the linked neuron next to it via exocytosisusing neurotransmitters to transfer neuronal information between nerve cells as well as to other muscle or gland cellsextra neurotransmitters are repeatedly removed from the synaptic cleft.
References
Artificial Neural Network: tutorials point, simply easy learning PDF, page 8, no author cited, 2017, http://www.tutorialspoint.com
Sage Publications, “Neurons, Neurotransmission and Communication”, by Jim Barnes, 2012
Click to access 61038_book_item_61038.pdf
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