• Diffusion is a critical process, which takes place not only in biology but in the various other branches of science. It involves the movement away of particles from an area of high concentration to an area of low concentration until an equilibrium is attained.

  • This movement happens spontaneously, and it doesn’t require any external energy source. This is because particles naturally exhibit random motion and the tendency for things to spread out – often described as moving down the concentration gradient.

  • The speed of diffusion is influenced by several factors, including temperature, particle size, and the concentration gradient. A higher temperature increases the energy of the particles, thus causing faster movement and quicker diffusion. Smaller particles also have a higher rate of diffusion as they can move more easily and quickly. The steeper the concentration gradient (the greater the difference between the high and low concentration), the quicker the diffusion.

  • Diffusion plays a vital role in biological systems. Some substances, like oxygen, can diffuse directly across the cell membrane due to their small size and lipid-solubility.

  • For larger or charged particles that can’t freely cross the cell membrane, transport proteins come into play. They provide passageways through the lipid bilayer, assisting in the diffusion of these particles - this is known as facilitated diffusion.

  • Some important examples of diffusion in the human body include the exchange of oxygen and carbon dioxide between lungs and blood during respiration, or the absorption of nutrients in the small intestine.

  • It’s key to remember that diffusion is a passive process - it involves movement of molecules from an area of high concentration to an area of low concentration without the use of energy.