The human brain has about 100 billion neurons. To learn more about how neurons carry messages, read about the action potential . Some of the smallest neurons have cell bodies that are only 4 microns wide, while some of the biggest neurons have cell bodies that are 100 microns wide. Neurons have a nucleus that contains genes. Neurons carry out basic cellular processes like protein synthesis and energy production.
Neurons have specialized extensions called dendrites and axons .
Dendrites bring information to the cell body and axons take information away from the cell body. Neurons communicate with each other through an electrochemical process. Actually, these cells have 2 axons rather than an axon and dendrite. One axon extends centrally toward the spinal cord, the other axon extends toward the skin or muscle. Covered by a membrane.