Summary
The nervous system is made up of neurons and glia. Neurons are specialized cells that are capable of sending electrical as well as chemical signals. Most neurons contain dendrites, which receive these signals, and axons that send signals to other neurons or tissues. There are four main types of neurons: unipolar, bipolar, multipolar, and pseudounipolar neurons. Glia are non-neuronal cells in the nervous system that support neuronal development and signaling. There are several types of glia that serve different functions.
Glossary
astrocyte
glial cell in the central nervous system that provide nutrients, extracellular buffering, and structural support for neurons; also makes up the blood-brain barrier
axon
tube-like structure that propagates a signal from a neuron’s cell body to axon terminals
axon hillock
electrically sensitive structure on the cell body of a neuron that integrates signals from multiple neuronal connections
axon terminal
structure on the end of an axon that can form a synapse with another neuron
dendrite
structure that extends away from the cell body to receive messages from other neurons
ependymal
cell that lines fluid-filled ventricles of the brain and the central canal of the spinal cord; involved in production of cerebrospinal fluid
glia
(also, glial cells) cells that provide support functions for neurons
microglia
glia that scavenge and degrade dead cells and protect the brain from invading microorganisms
myelin
fatty substance produced by glia that insulates axons
neuron
specialized cell that can receive and transmit electrical and chemical signals
nodes of Ranvier
gaps in the myelin sheath where the signal is recharged
oligodendrocyte
glial cell that myelinates central nervous system neuron axons
radial glia
glia that serve as scaffolds for developing neurons as they migrate to their final destinations
satellite glia
glial cell that provides nutrients and structural support for neurons in the peripheral nervous system
Schwann cell
glial cell that creates myelin sheath around a peripheral nervous system neuron axon
synapse
junction between two neurons where neuronal signals are communicated