The central nervous system (CNS) is the brain and spinal cord, and the peripheral nervous system (PNS) is everything else ( Figure 12.2 ). Relate the functional and structural differences between gray matter and white matter structures of the nervous system to the structure of neurons

The picture you have in your mind of the nervous system probably includes the brain , the nervous tissue contained within the cranium, and the spinal cord , the extension of nervous tissue within the vertebral column. That suggests it is made of two organs—and you may not even think of the spinal cord as an organ—but the nervous system is a very complex structure.

nervous system — composed of many organs that all look similar and can only be differentiated using tools such as the microscope or electrophysiology. neuron — neural tissue cell that is primarily responsible for generating and propagating electrical signals into, within, and out of the nervous system. peripheral nervous system (PNS) — anatomical division of the nervous system that is largely outside the cranial and vertebral cavities, namely all parts except the brain and spinal cord. brain — the large organ of the central nervous system composed of white and gray matter, contained within the cranium and continuous with the spinal cord.

Be able to identify the anatomical and functional divisions of the nervous system; list the basic functions of the nervous system; describe the basic structure of a neuron.