use it controls activities of the body unconsciously. Examples of involuntary functions are controlling heart rate, blood circulation, respiration, and digestion. Autonomic functions are also influenced by the person’s emotions. The autonomic nervous system is divided into two parts: sympathetic and the parasympathetic system. The sympathetic system sends impulses that speed up the body’s response to pain, anger, and fear. The parasympathetic system controls involuntary functions such as secretion and digestion. Both of these systems work in the reverse order to balance out the other. For example, the sympathetic system speeds up the heartbeat, while the parasympathetic system slows down heartbeat. The most important element in the autonomic nervous system is the hypothalamus, which helps control the internal body, such as temperature, water balance, and food intake. The hypothalamus sends messages to the autonomic nervous system and it takes the appropriate action. For example, in cold temperatures the hypothalamus sends messages that the body is cold. The sympathetic system creates goose bumps by contracting the skin. The sympathetic system activates the adrenal medulla, a gland that helps humans release stress. It releases two chemicals (adrenaline and noradrenaline) into the bloodstream, which transports them to all tissues of the body. Adrenaline excites the heart to increases muscle strength, like the reaction that comes from anxiety. Noradrenaline constricts blood vessels and helps transmit nerve signals. These chemicals are vital to many autonomic activities.Although the autonomic nervous system acts automatically, it is possible to have control of some autonomic functions. Biofeedback is teaching a person to control body functions like reducing heart rate. The benefits are that it can be used to relieve headache by moving blood away from the head to lessen pressure or by lowering high blood pressure. The fact that t...
