HUMAN PHYSIOLOGY: INTRODUCTION 301 



They are therefore known as food accessories. They are not 

 absolutely necessary as part of the diet, but, used in limita- 

 tion, they stimulate the appetite and favor the flow of diges- 

 tive juices. They, therefore, have a place upon the table. 

 If used in excess, however, they destroy the normal appetite 

 for natural flavors and may over-stimulate the glands that 

 furnish the digestive juices. 



Stimulants. — There are certain other substances that 

 primarily excite or stimulate the activity of certain parts 

 of the body, chiefly the nervous system, without providing 

 material for growth or repair, for heat or energy. These 

 are stimulants. They are chiefly tea, coffee, cocoa, chocolate 

 and alcoholic liquors. While in small amounts these may 

 be harmless, it is not easy to tell how small this amount 

 should be, and it differs with different dispositions. 



Their chief injury to the body lies in the fact that, by 

 stimulating the nervous system, they deprive the body of 

 the sense of fatigue, or of the desire for sleep, and so also 

 of the benefits derived from rest and sleep. 



Alcohol. — A true food is a substance which nourishes the 

 body, acts as a tissue builder or as a heat and energy producer. 



It has been determined by experiment, that in very small 

 amounts given at stated and widely separated periods, 

 alcohol is oxidized in the body, and thus produces heat and 

 energy as do the fat and carbohydrate foods. These are 

 such doses as the physician sometimes gives when for some 

 reason he must find an equivalent for fats and carbohydrates. 



In large amounts, alcohol has been found to act as a 

 drug, causing much harm to the tissues, poisoning them and 

 disarranging them seriously. 



Like other stimulants, and acting more quickly and in- 

 juriously, it excites the nervous system in a peculiar manner. 

 Unlike other poisons, its use establishes a craving or appetite 

 for it which eventually weakens the will and is apt to lead 

 to intoxication. 



