Breathing ~ The Human Lungs

 BREATHING 

 BASICS 

• Air is constantly moved in and out of the lungs 
• Known as ventilation 
• Pressure changes and that is what leads to inspiration and expiration
• Breathing in oxygen and breathing out carbon dioxide maintains a steep diffusion gradient

 INSPIRATION 

• Breathing in 
• Active process
• External intercostal muscles contract 
• Internal intercostal muscles relax
• Ribs are pulled upwards and outwards, increasing the volume of the thorax
• Diaphragm muscles contract and flatten, increasing the volume of the thorax
• The increased volume in the thorax means the pressure in the lungs is reduced
• …