Diffusion

Definition

• Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration, without requiring external energy.
• Known as passive transport since it doesn't require external energy.

Mechanism

• Occurs when particles are mobile or free to move across a concentration gradient.
• Concentration gradient: Different concentrations in different regions, with high concentration on one side and low concentration on the other.
• Substances move from regions of abundance to regions of demand (lower concentration).

Examples in Biology

• Human Body:
  • Oxygen diffusion in the lungs: Oxygen moves from alveoli (high concentration) to the blood (low concentration).
  • Blood takes up oxygen using passive transport.

Facilitated Diffusion

• Involves carrier proteins that assist in transporting substances across cell membranes.
• Example:
  • Oxygen binds with red blood cells in the bloodstream through facilitated diffusion, leading to oxygenated blood.
• This process is more sophisticated than simple diffusion and involves protein facilitation.