There are about 100 billion in the brain and 13.5 million in the spinal cord ... The involuntary part of the PNS includes the sympathetic, parasympathetic, and enteric nervous systems.

is a potentially life-threatening condition that occurs in individuals with a spinal cord injury. Patients usually present with elevated blood pressure and bradycardia. Noxious stimuli to intact ...

It is classified in two divisions—the sympathetic and parasympathetic systems ... nervous system comprises neurons in the brain and spinal cord, the sympathetic, or peripheral, autonomic ...