Sympathetic and Parasympathetic Nervous system

Sympathetic Nervous system

(1) Sympathetic Nervous System is formed by 22 pairs of sympathetic ganglia. These ganglia are linearly arranged on two sympathetic cords. Sympathetic nerve cords run on either side of the vertebral column. 

 (2) Sympathetic nerve cords are connected to CNS by rami communicans of spinal nerve fibers. 

 (3) This system works during stress, pain, anger, fear or emergency. It is supposed to bring about fight, flight or fright reactions. 

(4) Action of sympathetic nervous system is dependent on adrenaline or noradrenaline. The neurotransmitter is secreted by the sympathetic nervous system as an emergency hormone.

 Parasympathetic Nervous system

(1) Parasympathetic nervous system consists of nerve fibers of some cranial nerves, sacral nerves and parasympathetic ganglia. 

 (2) These parasympathetic ganglia are present on the sides of visceral organs like heart lungs, stomach, kidney, etc. 

 (3) Parasympathetic parasympathetic ganglia gives out fibers which innervates these involuntary organs. 

 (4) Parasympathetic nervous system works through release of acetylcholine which acts as neurotransmitter. It is an inhibiting neurotransmitter which affects visceral organs. 

 (5) This system works during rest and brings about relaxation, comfort, pleasure, etc.