350 



Our Surroundings 



Glass PI Tube 



Notice that the lime water becomes milky in appearance. Carbon 

 dioxide, a waste gas thrown off by breathing, causes the change 

 in the lime water. 



Experiment to Illustrate the Action of the Lungs and 

 the Diaphragm in Breathing. Remove the bottom from a 



large water bottle. Insert a 

 Y-tube into the bottle, pass- 

 ing the upper end up through 

 the cork of the bottle after 

 attaching a small balloon to 

 each branch of the tube. Ad- 

 just the tube so that the bal- 

 loons will be suspended free 

 in the bottle. Then tie a piece 

 of sheet rubber, to the middle 

 of which a cord has been at- 

 tached, over the opening in the 

 bottom of the bottle. The rub- 

 ber represents the diaphragm 

 and the balloons the lungs. 

 When the cord is pulled the 

 rubber will come down and 

 the air pressure in the bottle will be reduced. The balloons will 

 immediately expand, owing to the air pressure down the tube. 

 When the rubber returns to its former position the air in the 

 balloons will pass out through the opening in the tube and they 

 will become less rigid. How does this experiment represent the 

 action of the lungs and diaphragm in breathing? 



SUMMARY 



Respiration is the life process by which energy is made avail- 

 able in the body. It includes breathing and oxidation. 



Breathing is the process by which air is taken into the lungs 

 and carbon dioxide is removed from them. 



Oxidation in the body is the combining of oxygen taken from 

 the air with food substances in the cells. It releases energy for 

 the body's needs. 



Cork 



Bottle 



with bottom 

 removed 



Balloons 



nrlubber Diaphradrn 

 r o 



APPARATUS TO SHOW THE PROCESS 

 OF BREATHING 



