This is the body’s main coordinating system. It takes all the input from the environment that enters the body through the brain and all nerve tissues, and sends messages to various parts of the body.
The body’s nervous system is made up of two parts: the central nervous system and the peripheral nervous system.
The Central Nervous System
As shown in the illustration above, this is made up of the brain and the spinal cord and is the body’s processing center. It is responsible for the regulation of the body’s vital functions, e.g. breathing, heart beat, sensations, and movement, among others.
The brain is the body’s most vital organ. It processes inputs and transmits the responses to the other parts of the body.
It is generally divided into four lobes: frontal lobe, parietal lobe, temporal lobe, and occipital lobe. These along with the cerebellum and the brain stem make up the entire brain system.
The frontal lobe is responsible for problem solving, emotional traits, reasoning, speaking, and voluntary motor activity.
The parietal lobe is responsible for your sense of direction, sensation, reading, and body orientation.
The occipital lobe is responsible for vision and color perception.
The temporal lobe is in charge of understanding language, behavior, memory, and hearing.
The cerebellum is in charge of balance, coordination and control of voluntary movement, and fine muscle control.
The brain stem is in charge of breathing, body temperature, digestion, alertness or sleep, and swallowing.
The spinal cord is a length of nerve cells that run from the brain stem to the end of the spine. It is responsible for connecting the brain to the rest of the body, including the limbs.
The Peripheral Nervous System
This is the part of the nervous system that feeds information from most of the body’s senses into the brain. Some of these signal include those concerned with muscle movement and those from unconscious processes such as heartbeat and breathing.
This division of the nervous system is made up of two parts:
- somatic nervous system controls all skeletal muscle motor function and governs voluntary movements and reactions
- autonomic nervous system regulates automatic processes such as heartbeat, blood pressure, breathing, sweating and digestion; this is the part that is being monitored using the sensors in the polygraph machine; it is further divided into two parts:
- sympathetic directs the body’s fight or flight response
- parasympathetic in charge of relaxing the body to conserve and maintain energy