The cause of your nervous system is genetics.
stimulants
The sympathetic division of your autonomic nervous system (ANS) increases the activity of most bodily systems excepting the digestive and urinary. The layman's term for the sympathetic nervous system is the "fight-or-flight" nervous system. The parasympathetic nervous system is the other division of the ANS and is termed the "rest and digest" nervous system.
the connection between the two is like this. the nervous system sends the signal to the skeletal muscle to contract. This contraction causes the muscle to pull the bone, and the bone bends. This would mean that the movement of the skeleton is caused by nervous system which triggers the skeletal muscle to move the skeleton.
Physical injury is one of the most common causes of damage to the nervous system.
stimulant
stimulant
stimulant
stimulant
Reflex Arc
Autonomous nervous system. Consisting of Parasympathetic nervous system and Sympathetic nervous system. Parasympathetic nervous system increases the secretions of digestive tract and Sympathetic system decreases the secretions. Parasympathetic system increases the contractions of smooth muscles and increases the rate and force of peristalsis and Sympathetic system does vise verse.
The sympathetic nervous system increases blood pressure by releasing adrenaline, which causes blood vessels to constrict and the heart to beat faster and stronger. This response helps the body prepare for fight or flight situations.