Ralph Hutchings

Image 64 of 74
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Resin cast of the human bronchial tree (yellow) and the airways of the lungs (white). The lungs take in around 0.5 liters of air in every breath, with around 12 breaths per minute at rest. The lungs have a large network of airways, which gives them a huge surface area for oxygen to diffuse into the blood and carbon dioxide to diffuse out.