Organization of the nervous system

The primary organization of the nervous system is into the central and peripheral nervous systems. 

The central nervous system (CNS) consists of the brain and spinal cord. The brain is located in the skull and it the central control point of the nervous system.

It generates the commands about how the peripheral tissue should function, while also receiving sensory information about the state of those tissues. The brain processes that information, based on which it generates new commands on tissue functioning in order to preserve bodily homeostasis. The spinal cord continues to the inferiormost part of the brain and it is located in the vertebral canal of the spine.

It is a conduit for the signals coming from the brain, responsible for distributing them throughout the set of spinal nerves that emerge from it. Besides conducting the information, the spinal cord is also capable of generating some on its own, but mostly the involuntary reflexes.

The peripheral nervous system (PNS) consists of all the other nervous tissues beyond the CNS (e.g. cranial nerves, spinal nerves, plexuses, ganglia). Functionally, the PNS is divided into:

• Autonomic nervous system (ANS), which is the center of involuntary activities of our body (e.g. heartbeat, breathing, etc.). This system is further subdivided into two divisions: sympathetic nervous system (SNS) and parasympathetic nervous system (PSNS).  Some authors describe them as antagonistic, however they are rather complementary with each other, since without the functions of one, the function of the other would be impaired.
• Somatic nervous system (PNS), which is the center of voluntary bodily functions (e.g. speech, movement)

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