21st Century Biology    Back to Brain Awareness Week  The Neuron
Function of a Neuron  Neurons, or nerve cells, are the
functional unit of the nervous system for transmitting signals
through the body. They regulate the contraction of muscles and
secretion of hormones.  Organization of a Neuron  Neurons have
three main parts.   1. The cell body (yellow) contains the
nucleus, endoplasmic reticulum, mitochondria, nissel bodies etc.
2. Dendrites (purple) are short extentions of the cell body.
They receive information, and transmit it to the cell body.
Dendrites can be compared to the hearing part of a telephone--
the dendrite hears a message that is being sent from sensory
receptors or another neuron.   3. The Axon (orange) is a thin
tube that can be up to 3 feet long. This part of the neuron
takes impulses away from the cell body. Following the same
metaphor, the axon is like the telephone wire that transmits the
message. Axons are insulated by the myelin sheath (blue) that
are the stacked membranes of Schwan