XVIII. THE HUMAN MACHINE AND ITS NEEDS 



Problem. To obtain a general understanding of the parts 

 and uses of the bodily machine. 



LABORATORY SUGGESTIONS 



Demonstration. Review to show that the human body is a complex of 

 cells. 



Laboratory demonstration by means of (a) human skeleton and (b) 

 manikin to show the position and gross structure of the chief organs of 

 man. 



Man and his Environment. In the last chapter we saw that 

 one factor in the improvement of man lies in giving him better 

 surroundings. It will be the purpose of the following chapters 

 to show how man is fitted to live in the environment in which 

 he is placed. He comes in contact with air, light, water, soil, 

 food, and shelter which make his somewhat artificial environment ; 

 he must adapt himself to get the best he can out of this environ 

 ment. 



The Needs of Living Things. We have already found that the 

 primary needs of plants and animals are the same. They both 

 need food, they both need to digest their food and to have it cir 

 culate in a fluid form to the cells where it will be used. They 

 both need oxygen so as to release the energy locked up in their 

 food. And they both need to reproduce so that their kind may be 

 continued on the earth. What is true of plants and other animals 

 is true of man. 



The Needs of Simple and Complex Animals the Same. 

 The simplest animal, a single cell, has the same needs as the most 

 complex. The cell paramcecium feeds, digests, oxidizes its food, 

 and releases energy. The cells of the human body built up into 

 tissues have the same needs and perform the same functions as 

 the paramcecium. It is the cells of the body working together 



266 



