1.3.2 Factors that Affect Diffusion

Key Factors Influencing Diffusion:

1. Concentration Gradient: The concentration gradient is the difference in the concentration of particles between two areas.

Effect: The steeper the concentration gradient, the faster the rate of diffusion. A greater difference in concentration leads to more particles moving from high to low concentration.

2. Temperature: Temperature affects the kinetic energy of the particles involved.

Effect: Higher temperatures increase the kinetic energy of particles, causing them to move faster. This results in an increased rate of diffusion. Conversely, lower temperatures slow down particle movement, reducing the rate of diffusion.

3. Surface Area: The surface area over which diffusion occurs plays a crucial role in determining how quickly substances can move.

Effect: Larger surface areas provide more space for particles to diffuse across, increasing the rate of diffusion. This is particularly important in biological systems, such as the alveoli in the lungs or the villi in the small intestine, where large surface areas facilitate efficient gas and nutrient exchange.

4. Distance: The distance that particles need to travel during diffusion also impacts the rate.

Effect: Shorter diffusion distances result in faster diffusion. In biological systems, cells and tissues are often thin to reduce the distance over which diffusion must occur, ensuring that substances are quickly delivered or removed.

5. Nature of the Diffusing Substance: The size and type of particles can influence how easily they diffuse.

Effect: Smaller molecules (e.g., oxygen and carbon dioxide) diffuse faster than larger molecules. Additionally, nonpolar molecules generally diffuse more easily through cell membranes than polar molecules due to their solubility in lipids.

Biological Importance:

• Efficient Gas Exchange: In the lungs, oxygen diffuses rapidly from the alveoli into the blood due to the large surface area, steep concentration gradient, and short diffusion distance.
• Nutrient Absorption: In the small intestine, nutrients diffuse into the bloodstream through the villi, which have a large surface area and thin walls, maximizing the diffusion rate.
• Waste Removal: Diffusion is crucial for removing waste products like carbon dioxide from cells into the blood for exhalation.