FEATURES OF A GOOD GAS EXCHANGE SURFACE:
• large surface area for the alveoli
• numerous capillaries around the alveoli
• thin walls of the alveoli and capillaries meaning a short distance between the alveolar air and
the blood in the capillaries
THE RATE OF DIFFUSION DEPENDS ON:
• surface area – rate of diffusion is directly proportional to the surface area
• concentration gradient – rate of diffusion is directly proportional to the difference in concentration across the gas exchange surface.
• thickness of the gas exchange surface – the rate of diffusion is inversely proportional to the thickness of the gas exchange surface. (the thicker the surface the slower the rate of diffusion)
