The nervous system is a very fascinating system it is broken into two parts and is collaborates and functional with every other system in the body, particularly the endocrine system. The nervous system is broken down into the Central Nervous System, which consist of the brain and the spinal cord (with its afferent and efferent neurons). The other system is called the peripheral (so named because it handles things which are not normally consciously focused upon to be maintained in the human body). This system is broken down yet again: The somatic, which transmits messages from information from the sensory organs to the CNS's afferent neurons, which carry the information to the brain and the autonomic which is manly responsible for the "flight or fight response". The autonomic system is broken down into two final parts. The sympathetic (probably named because the body is assumed to be sympathetic to the needs of the situation) and the parasympathetic. These two work parallel to each other. Upon danger the sympathetic system causes the body to dilate the pupils, accelerate heartbeat, constrict arterioles, dilates bronchi, inhibits motility and secretion, inhibits pancreas and adrenals, inhibits intestinal motility, and relaxes the bladder.