CHAPTER XXXIV 

 OUR NERVOUS SYSTEM AND HOW IT WORKS 



In studying the muscular system, the circulatory sys- 

 tem, and the other wonderful working parts of our bodies, 

 we have seen how each has its own vital task to perform. 

 We have seen, too, that each system depends on every 

 other system to such an extent that if one breaks down or 

 fails to work properly all others are seriously affected. 

 Good "team work" is necessary for health. 



So complicated and so interrelated are our bodily 

 processes that general control and direction are necessary 

 for bodily health and for usefulness. This is the particular 

 task of our nervous system, consisting of brain, spinal cord 

 and nerves. 



We may think of the brain as in authority, recording 

 and classifying information coming from all parts of the 

 body, deciding on action and issuing orders to the 

 muscles. For this work the nervous system becomes the 

 bodily telephone exchange. The nerves are the individual 

 wires, reaching every part of the body. The spinal cord is 

 a trunk line, gathering these wires into large groups. The 

 brain acts as a central switchboard. 



This wonderful apparatus is automatic to a surprising 

 extent, in part from habit, having made the same connec- 

 tions with certain muscles for certain acts, over and over 

 again. How this delicate, sensitive apparatus is con- 

 structed and protected and how it works is a story well 

 worth knowing. 



The word coordination is used to express the idea of the 

 cooperation, or working in harmony, of the various parts of the 

 body. You have undoubtedly noticed that in as simple an act as 

 spreading butter on bread, one hand holds the bread, and the 

 other the knife, and the movements of both hands are such as to 

 effect the purpose desired. Numerous illustrations of cooperation 

 of parts of the body may easily be found. They occur in dancing, 



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