The myelin sheath is a fatty substance that often covers axons, acting as an insulator. This covering is crucial for increasing the speed at which neural impulses are transmitted along the axon.

Myelin Sheath

Cells that create and apply the myelin in the peripheral nervous system. 

Grinnell College

The main types of the neurons (nerve cells) and the glial cells, which come in various forms.
- astrocyte
- microglial cell
- oligodendrocyte
- Schwann cell

Specialized Cells

Breedlove, S. & Watson, N. (2017). Behavioral neuroscience, eighth edition. Oxford University Press.

Behavioral Neuroscience 8th Edition

Neurons, also known as nerves if they're in the peripheral nervous system, are the information carriers. There are aproximately 80-90 billion neurons in the adult human brain, arranged in complex networks and circuits that control behavior and body functions. The current theory about neurons is the neuron doctrine.

Neurons

The star-shaped cell. It extends in multiple directions connecting to multiple neurons. Astrocytes recieve synapses directly from neurons and seems to share information between multiple neurons at once. There is evidence that the astrocyte acts as a tripartite synapse. They are also involved in the formation and pruning of synapses.

Astrocyte

They are very small, highly active cells that continuously extend and withdraw. They act in sites of damage to form containment zones around the injury. It acts as a cleanup crew to remove debris from injured or dead cells. They also appear to be involved in the neural pain systems.

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