Nose or Mouth - cilia which traps mucus,lowers chance of infectious organisms reaching lungs.
Tranchea - wide tube, epiglottis closes over when we swallow.
Bronchi - also have cartilage in their walls
Bronchioles - also have cartilage in their walls, some only have muscle and elastic fibres though - so they can expand and contract easily during ventilation.
Effecient gas exchange surface needs..
- A large surface area, compared to the volume of the organism. - Each bronchus divides repeatedly into small tubes called bronchioles which lead to a vast number of very small alveoli…