This video defines diffusion, and uses the particle model to illustrate the factors that affect diffusion. It then uses calculations to show that multicellular organisms have a smaller surface area to volume ratio than smaller, unicellular organisms and how this impacts of diffusion rates. Finally, the video explores diffusion in the context of the breathing system and food absorption in the small intestine.

Key Words

concentration, diffusion, alveoli, trachea, bronchioles, lumen

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