CHAPTER XVII 

 RESPIRATION AND EXCRETION 



Prot)lems : A study of respiration to find out: 

 {a) What changes in the blood and in the air take place within the 

 lungs. 



(h) The mechanics of respiration. 

 A study of ventilation to discover : 

 (a) The reasons for ventilation. 

 (6) The best method of ventilation. 

 A study of the organs of excretion. 



Laboratory Suggestions 



Demonstration. Comparison of the lungs of the frog with those of a bird or 

 a mammal. 



Experiment. The changes taking place in the air in the lungs. 



Experiment. The use of the ribs in breathing. 



Demonstration experiment. What causes the filling of air sacs in the lungs? 



Demonstration or home experiment. How to perform the Schaefer method 

 of artificial respiration. 



Demonstration experiment. Best methods of ventilating a room. 



Demonstration. Best methods of dusting and cleaning. 



Demonstration. Beef or sheep's kidney to show its structure. 



Necessity for Respiration. — We have seen that plants and 

 animals need oxygen in order that the life processes may go on. 

 Food is oxidized to release energy, just as coal is burned to give 

 heat to run an engine. As a draft of air is required to make a fire 

 under the boiler, so, in the human body, oxygen must be given so 

 that food in the tissues may be oxidized to release energy- used in 

 work. This oxidation takes place in the cells of the ])ody, be they 

 part of a muscle, a gland, or the brain. 



The Organs of Respiration in Man. — We have noted the fact 

 that the lungs are the organs which give oxygen to the blood and 

 take from it carbon dioxide. Air passes through the nostrils into 

 the windpipe. This cartilaginous tube, the top of which may 



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