Central nervous system (CNS) – consists of the brain and spinal cord
Peripheral nervous system (PNS) – peripheral nerves and ganglia
Nervous system is divided functionally into two major components:

Somatic nervous system – conscious voluntary movements
Autonomic nervous system – regulates the functions of internal organs – further divided into two subdivisions:
Sympathetic nervous system – involved in functions requiring quick responses (i.e., stress, impending danger, and fight or flight response)
Parasympathetic nervous system – regulates functions that do not require a quick response
Although the CNS will be briefly examined, most of the emphasize will be on the PNS.