Neurons

Neurons or nerve cells are the fundamental units of the nervous system, the complex network that controls and communicates information in the body. Neurons are specialized to transmit information throughout the body.

Structure

Neurons are cells with a number of long processes extending far from the nucleus. The human brain contains approximately 86 billion neurons. Each neuron is composed of a cell body or soma, dendrites, and an axon.

Soma

The soma is the cell body of the neuron. It contains the nucleus of the cell and is where the majority of the cell's protein synthesis occurs.

Dendrites

Dendrites are extensions of the neuron with many branches, and are the main components for receiving signals from other nerve cells.

Axon

The axon is a much longer process, and it carries nerve signals away from the soma (and also carries some types of information back to it).

Function

Neurons communicate with each other via synapses, tiny gaps where a dendrite from one neuron can interact with another neuron's axon. The neuron sending the signal is called the presynaptic neuron, and the neuron receiving the signal is called the postsynaptic neuron.

Classification

Neurons can be classified by the direction that they send information. Afferent neurons convey information from tissues and organs into the central nervous system and are also called sensory neurons. Efferent neurons transmit signals from the central nervous system to the effector cells and are also called motor neurons.

See also

• Nervous system
• Nerve
• Brain
• Spinal cord
• Synapse

References

Neurons Resources
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