Autonomic nervous system consists of 1:12 Parasympathetic nerves from cranio-caudal outflow as well as the brain centres that mediate them in the pontomedullary axis with the hippocampal gyrus as the highest point of control in the mid brain.2.The Sympathethic nervous outflow as their synaptic control centres in the central nervous system as well as peripherl ganglia like , cervical,coeliac,aortic ,pelvic or iliac ganglia and plexuses respectively.
They serve to maintain homeostasis or vegetative functions of the body and work in opposition to each other.When the sympathethic system is enhancing a process in the body the parasympathethic is opposing such function and vice versa.
Heart rate ,Body temperature,blood pressure,Respiratory rate as well as the bodys' 'fight or flight mechanism are all controlled by the autonomic nervous system.