2.5 Diffusion gradients

Concentration gradient

a difference in the concentration of a substance between two regions

How are steep diffusion gradients maintained?

Two processes work together:

Ventilation: replaces alveolar air, bringing in oxygen and removing carbon dioxide

Blood supply: Carries oxygen away and brings more carbon dioxide-rich, deoxygenated blood to the lungs

Diffusion, osmosis, active transport gradients

• high → low

• high → low

• low → high

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