Neurons (also known as neurones, nerve cells and nerve fibers) are a major class of cells (parenchyma) in the nervous system whose main role is to process and transmit information. In vertebrate animals, neurons are found in the brain, the spinal cord and in the nerves and ganglia of the peripheral nervous system.
Neurons are typically composed of a cell body, a dendritic tree and an axon. In the classic view of neuron function, the cell body and dendritic tree receive electrical signals from other neurons while the axon transmits electrical output signals. This is largely true for vertebrates. However invertebrate neurons are less well described in this manner.
Neurons are able to generate and propagate electrical impulses because they have excitable membranes. Neurons make connections with other neurons and transmit information to them via synaptic transmission. Different types of neurons have different shapes, possess specific electrical properties adopted for their function and use different neurotransmitters.