The nervous system in a human body is made up of the brain, spinal cord and billions of neurons. The system helps the body to stimuli, and regulates and controls the working of the internal organs. The nervous system is sub-divided into central and peripheral nervous systems. While most people are aware of the functions of the central nervous system, they do not know the peripheral nervous system (PNS) functions.
There 2 kinds of cells in the PNS, the sensory nerve cells and the motor nerve cells. The former is in charge of carrying information to the CNS when an external stimulus is, while the latter is in charge of carrying the information from the CNS to the organs, glands and muscles of the body.
The motor nervous system is further sub-divided into somatic and autonomic nervous systems. The former has the duty of controlling the skeletal muscles and external sensory organs; while the latter is primarily in charge of controlling involuntary muscles. The somatic nervous system is often called as a voluntary system since the responses from the system can be controlled by the person. The only exception to the rule is the reflex reaction of the skeletal muscles.
The autonomic nervous system is subdivided parasympathetic and sympathetic nervous systems. The former is responsible for controlling a variety of bodily functions, such as reducing the rate of the heart, constriction of pupils and contraction of the urinary bladder. The sympathetic nervous system works opposite to the parasympathetic nervous system. In addition, this is the seat of the flight-or-fight response that people show when they are in a dangerous situation. When danger is perceived by the sympathetic nervous system, it prepares the body either to run away from the danger or to stand and fight the danger. So, in a dangerous situation, the heart rate and the metabolic rate increase.
The main function of the peripheral nervous system is to convey messages from the brain and the CNS to different parts of the body. The system is connection that joins the central nervous system to the different glands, blood vessels, organs and muscles in the body. Any problem with the peripheral nervous system can have a profound effect on the body. It can disrupt the transportation of information from the CNS to the body and as a result the different parts will not be able to function properly. Any problem with the peripheral nervous system can result in weakness, losing control of the limbs, gradual and progressive loss of the senses and bowel incontinence.
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Buzzle.com: Peripheral Nervous System