CHAPTER XXI 

 USE AND CARE OF THE NERVOUS SYSTEM 



Activity of the nervous system. By means of the 

 nervous system, we get all our information as to the 

 outside world in the form of a constant stream of sen- 

 sations pouring in through each of our sense organs. 

 By means of it, also, our activities from the least to 

 the greatest, from the secretion in a tiny gland to the 

 putting forth of great muscular or mental effort, are 

 started and guided. During our waking hours, there is 

 no second of time when millions of neurons are not 

 actively at work. During our sleep, there is no time 

 when all the neurons are at rest, for the vital processes 

 of the body, the beating of the heart, the movements 

 of breathing, the activity of many glands, the resupply- 

 ing of tissues with food materials and the clearing away 

 of waste, must all be carried on. The nervous system 

 must therefore, in spite of its sensitiveness, be long en- 

 during, and it must further be cared for in such a way 

 as to keep it strong and efficient. Like all the other 

 tissues of the body, it develops strength through use 

 and thrives on good hard work, provided only that the 

 conditions under which it works are wholesome and 

 the \vork is not too long continued. 



Value of sleep. The most fundamental condition for 

 the health of the nervous system is sufficient regular 

 sleep. Sleep is more important even than food or drink, 

 since without it life more quickly becomes impossible. 



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