Module 5 - Polygraph Testing & Forensic Document Analysis

Organization of the Human Nervous System

Image courtesy of National Institutues of Health (www.diabetes.niddk.nih.gov):
Keep your nervous system healthy, September, 2003.

To understand the stress indicators that are exhibited by a person who is lying, one must learn some basics about the human nervous system, which is the area of the body that initiates the body's stress responses: .

The nervous system has two main parts: the central nervous system and the peripheral nervous system.  The central nervous system is comprised of all the neural matter in the brain and spinal cord; the peripheral nervous system contains all the neural matter outside the brain and spinal cord (such as limbs and organs).  The peripheral nervous system is composed of two parts: the autonomic nervous system and the somatic nervous system.  The autonomic system controls all the body's involuntary actions (such as breathing, digestive activities, and heart rate). The somatic nervous system controls the body's voluntaryactions (such as talking and walking).

The autonomic nervous system is further organized into the parasympathetic nervous system and the sympathetic nervous system.  The parasympathetic nervous system is responsible for maintaining all the body's involuntary actions during normal activities; the sympathetic nervous system controls all the body's involuntary actions during times of stress.

Image courtesy of National Institutes of Health (www.diabetes.niddk.nih.gov): 
Keep your nervous system healthy, September, 2003.

Did you know?

The rate of growth of the cells in the human nervous system during early pregnancy is 250 000 cells per minute.

Source:  http://faculty.washington.edu/chudler/facts.html#brain