Peripheral Nervous System
The peripheral system is made of two divisions, the somatic nervous system and the autonomic nervous system, which is further divided as the sympathetic nervous system and the parasympathetic nervous system. Each of these interact with various organs, glands or muscles, providing information to and from the central nervous system.
Autonomic Nervous System:
- the "involuntary" or autonomic nervous system is responsible for homeostasis, maintaining a relatively constant internal environment by controlling such involuntary functions as digestion, respiration, and metabolism, and by modulating blood pressure. Although these functions are generally outside of voluntary control, they are not outside our awareness, and they may be influenced by one's state of mind.
- The autonomic nervous system is divided into two subsystems, the sympathetic and the parasympathetic, which work in tandem, either in a synergistic or an antagonistic way. The sympathetic system is responsible for providing responses and energy needed to cope with stressful situations such as fear or extremes of physical activity. In response to such stress, the sympathetic system: raises blood pressure, heart rate, and the blood supply to the skeletal muscles at the expense of the gastrointestinal tract, kidneys, and skin; dilates both the pupils and the bronchioles, providing improved vision and oxygenation; and generates needed energy by stimulating glycogenolysis in the liver and lipolysis in adipose tissue. In general, it serves to stimulate organs and to mobilize energy.
- Between stressful situations, the body needs to rest, recover, and gain new energy. These tasks are under the control of the parasympathetic system, which lowers the heart rate and blood pressure, diverts blood back to the skin and the gastrointestinal tract, contracts the pupils and bronchioles, stimulates salivary gland secretion, and accelerates peristalsis. The parasympathetic system influences organs toward restoration and the saving of energy.
Detailed Graph of Details of the Individual Components of the A.N.S.:
Somatic Nervous System:
- The somatic nervous system is that part of the peripheral nervous system associated with the voluntary control of body movements through the action of skeletal muscles. The somatic nervous system consists of afferent fibers which receive information from external sources, and efferent fibers which are responsible for muscle contraction.