Biology AS (1) AQA Lungs

Ventilation Route...

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.

Alveoli - 

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…