Neuron
lastmod 2018-08-17created 2015-12-234 edits
A neuron (nerve cell) is the main cell that makes up the nervous system. By expressing ion channels such as sodium channels and potassium channels, neurons, unlike other cells, can transmit signals electrically. They also receive and store diverse information by exchanging signals with adjacent neurons through structures called synapses. The human brain is estimated to contain about 10 billion neurons in the cerebral cortex alone.
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Structure
- Cell body
- The cell body (soma) is the central part of the neuron and contains the cell's nucleus and organelles.
- Dendrite
- Dendrites extend out in numerous branches and are mainly the part where the neuron receives signals.
- Axon
- The axon is a very long extension from the cell body that transmits signals passed through the dendrites and cell body to other neurons or cells. The axon hillock, where the axon begins from the cell body, has a high density of voltage-gated sodium channels, which generate action potentials in response to incoming signals and transmit them along the axon.
- Synapse
- A synapse is a structure formed where two adjacent neurons meet. A signal transmitted electrically is converted into a chemical signal called a neurotransmitter and passes through the synapse. Relative to the synapse, the neuron sending the signal is called the presynaptic neuron, and the neuron receiving the signal is called the postsynaptic neuron. A single neuron forms roughly 1,000 or more synapses, which form the basis of neural networks, and the strengthening of synaptic signal transmission is accepted as the mechanism of learning and memory.