ANATOMY

Detailed explanation-1: -Membrane surface area – the larger the surface area, the faster the rate of diffusion. The lungs normally have a very large surface area for gas exchange due to the alveoli.

Detailed explanation-2: -The higher the temperature, the more kinetic energy the particles will have, so they will move and mix more quickly. The greater the surface area, the faster the rate of diffusion.

Detailed explanation-3: -Breathing in and out (a ventilation mechanisms) maintains a steep concentration gradient between the oxygen (and carbon dioxide) in the alveoli and the blood so that the rate of diffusion is faster.

Detailed explanation-4: -Thin lining: the lining of the alveoli is very thin so that gases can quickly diffuse through it. Large surface area: human lungs contain about 500 million alveoli, which creates a surface area around half the size of a tennis court. This speeds up diffusion because gases have more area over which to diffuse.

Detailed explanation-5: -Factors that affect the diffusional conductance of a gas include the thickness of the blood:gas barrier, the overall alveolar–capillary contact surface area, the solubility of the gas in the haemoglobin-free blood:gas barrier, and the molecular weight of the gas.