HYGIENIC ASPECTS OF NUTRITION 267 



cooking should always precede the introduction of food into 

 the body. The body is a machine, and food is the material 

 that builds it up and supplies the energy to run it. Filth and 

 disease bacteria interfere with the normal work and efficiency 

 of the machine. 



294. Circulation and nutrition. The r61e of the circulation 

 in carrying digested food to the tissues has already been dis- 

 cussed. It must be clearly understood, therefore, that anything 

 which makes the circulation abnormal will affect nutrition. In 

 most adults the heart beats about seventy-two times per min- 

 ute. In children and youths the rate is likely to be higher, 

 while in old people 'it may be lower. By placing a finger upon 

 the inside of the wrist one can usually feel the pulse, which 

 tells accurately how many times per minute the left ventricle 

 is contracting. Count your pulse beats during each of several 

 minutes and determine what the normal average is. By having 

 all members of the class of students report on such calculations 

 the average pulse and the greatest variation of pulses in the 

 class may be determined. After having determined the normal 

 pulse rate, if violent exercise is taken, it will be found that the 

 pulse rate has been increased. 



During severe exercise increased release of energy from 

 broken-down protoplasm takes place, and there is increased 

 demand for oxygen and food. This results in increased heart 

 action. In some cases of severe illness during high fever a 

 similar demand is made, with a similar increase of heart action. 

 Prolonged increase above the normal rate means excessive 

 wear upon the parts of the human machine that are affected. 

 A brief period of this unusual stimulation is not necessarily 

 harmful and may often be decidedly helpful. 



During digestion excessive exercise retards or stops the 

 digestive processes ; hence care should be taken to avoid vio- 

 lent exercise immediately after a heavy meal. Wild animals 

 which feed at irregular intervals, and eat to distention when 

 they do feed, usually become quiet and often sleep for some 



