McGraw-Hill Science Return to Book List
Sunflower Grade 2
 
Human Body: Heart and Lungs
 
Your Lungs at Work
 
  •  
    		• When you breathe in, your lungs take oxygen from the air. Oxygen is a gas you need to live.
  •  
    		• The diaphragm is the main muscle used in breathing.
  •  
    		• When you breathe in, your chest gets larger.
  •  
    		• When you breathe out, your lungs get rid of carbon dioxide, a waste gas.
  •  
    		• Your body makes carbon dioxide, but you do not need it. Too much of it can make you sick.
  •  
    		• When you breathe out, your chest gets smaller.