436 Our Surroundings 



body are affected, since the nervous system controls, coordinates 

 and adjusts all the organs of the body by means of stimuli or 

 nervous impulses which it originates and transmits. 



It is the function of the cerebellum to regulate and coordinate 

 the impressions which it receives from the trunk and limbs of the 

 body. The power of walking steadily and balancing the whole 

 body properly depends upon the normal functioning of the cere- 

 bellum. When this organ is disturbed -by alcoholic poison there 

 occurs more or less loss of control of the action of certain organs, 

 especially of the lower limbs. Hence the staggering movements 

 of the intoxicated man. Precision of movements of any kind 

 is rendered impossible. 



It is an accepted fact that alcohol and similar drugs attack 

 the more complex and more delicate parts of the body and seri- 

 ously injure them. Alcohol from the first has an unfavorable 

 influence on the finer brain cells. Since the brain is the organ of 

 the mind, the effect on thought and motion is soon apparent in the 

 conduct and work of man under the influence of liquor. 



Effect of Tobacco on the Nervous System. Nicotine, the 

 active agent in tobacco, acts on the nervous system as a poison. 

 Although the use of tobacco is not so serious in its effects as the 

 use of alcohol and certain other drugs, it often brings on a 

 nervous derangement known as "tobacco heart" and sometimes 

 causes a nervous disorder of the retina of the eye. 



SUMMARY 



Coordination means the working together in harmony of the 

 various parts of the body. This is brought about by the nervous 

 system. 



The most important parts of the nervous system are the brain, 

 the spinal cord and the nerves. 



The brain is composed of three principal parts, the cerebrum, 

 the cerebellum, and the medulla. 



The cerebrum is the seat of thought. 



The cerebellum regulates the movements of the parts of the 

 body. 



