HOW WASTES ARE REMOVED FROM THE BODY 145 



How wastes are 

 removed from the 

 human body. We 

 have seen that the 

 human body uses 

 foods wherever work 

 is done in it. After 

 the food is digested 

 in the food tube it 

 is absorbed by the 

 blood which carries 

 it through a system 

 of pipes called veins 

 to a pumping station 

 called the heart. 

 This is a double 

 station ; the left side 

 of it forces the blood 



The upper cavities in the heart are called auricles (right 

 or left), the lower, the ventricles (right or left). 

 Follow the arrows. In what respect is the heart 

 like a force pump ? 



through the arteries (see diagram) to all parts of the body, 

 while the right side pumps blood to the lungs. Here, as 



we have seen before, 



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The exchange between blood and the cells of the body. Called 

 H.-WHIT. CIV. SCI. IN THE HOME IO 



it gives up carbon 

 dioxide, and receives 

 its burden of oxygen. 

 Before the blood 

 reaches the cells, the 

 little units of building 

 material of which the 

 body is composed, the 

 vessels containing it 

 divide into tiny tubes 

 capillaries. 



