Breathing

• Breathing in:

  • External intercostal muscles contract – pulls rib cage upwards and outwards
  • Diaphragm muscles contract – diaphragm moves downwards
  • Lung volume increases – and pressure falls
  • Air rushes in to equalise pressure

  
• Breathing out:

  • External intercostal muscles relax – rib cage falls downwards and inwards
  • Diaphragm muscles relax – returns to dome shape
  • Lung volume decreases – and pressure increases
  • Air is forced out

  
• Internal intercostal muscles: are used in coughing and sneezing.

  
• Mucus & cilia: goblet cells produce sticky mucus to trap and eliminate particulate matter and microorganisms.

  
• Ciliated cells have cilia: little hairs which sweep back and forward in a coordinated way to brush mucus up the lungs into the mouth