Cells of the nervous system, called nerve cells or neurons, are specialized to carry messages through an electrochemical process. The human brain has approximately 100 billion neurons. To learn how neurons carry messages, read about the action potential.Neurons come in many different shapes and sizes.Some of the smallest neurons have cell bodies that are only 4 microns wide. Some of the biggest neurons have cell bodies that are 100 microns wide. (Remember that 1 micron is equal to one thousandth of a millimeter!).owever, neurons differ from other cells in the body because: 1  Neurons have specialize cell parts called dendrites and axons. 2  Neurons communicate with each other through an electrochemical process. 3  Neurons contain some specialized structures (for example, synapses) and chemicals (for example, neurotransmitters).