Mechanics of Breathing - Answers

• When the diaphragm contracts, what happens to its shape and position?
  


• It flattens and moves down




• How is air drawn into the lungs?
  
  
  • An increase in space within the chest cavity occurs when the diaphragm flattens and the intercostal muscles expand the rib cage
  
  
  • The increase in space means the air pressure is lower inside than outside, causing a rush of air into the lungs
  
  
  
• Which part of the brain controls the breathing rate?
  
  
  • Medulla oblongata
  
  
  
• What do stretch receptors within the bronchi and bronchioles do?
  
  
  • Prevent excess inspiration
  
  

• If carbon dioxide levels get too high, what happens to increase the rate of ventilation and remove the excess CO2?


• Carbonic acid is released which causes an increase in Hydrogen ions. This rise stimulates increased ventilation.