2 Physiology. 



air as those who live outdoors. An indoor life is always 

 more or less artificial, and we need to take especial care 

 that our bodies do not suffer. It is believed that one 

 seventh of the deaths among civilized races are due to lung 

 troubles. Those who live outdoors have little trouble of 

 such kind. We need to learn about the air and breathing, 

 about exercise and bathing, about food and digestion, about 

 blood and its circulation, about the nervous system, etc. 



Hygiene. Hygiene is the art of preserving the health. 

 This is the main object of our study of this subject. 



Physiology. Physiology is the science of the action of 

 the body and its various parts. We must know the natural 

 action of the parts of the body to be able to keep them in 

 good working order. 



Organ. An organ is any part of the body that has a 

 special work to do, as the hand, eye, or heart. 



Function. The work or action of an organ is its 

 function. 



Anatomy. Anatomy is the science of structure. We 

 need to know something of the structure of our bodies. 

 For this purpose we may study the internal structure of 

 the sheep, pig, calf, and rabbit which is very similar to 

 our own. . We can take the hearts, lungs, brains, eyes, arid 

 muscles of such animals to learn the structure of these 

 organs in our own bodies ; if we are not willing to do this, 

 we can never get a clear understanding of the subject. 



Tissues. Every organ is made up of several different 

 kinds of material. For instance, in a slice across a ham 

 we see skin on the outside, then fat meat, lean meat, and 

 bone. These " primary building materials " of the body 



