Why Is Diffusion Important In Cells?

Substances can be transported actively using energy and special carrier molecules from one part of the cell to another or from one cell to another cell. But why waste energy when diffusion can do the job?

Many substances diffuse in and out of cells from a region of high concentration to a region of low concentration, and no energy is used in the process. One example is when you breathe fresh air into the lungs. The new air contains more oxygen than the blood just inside the lungs. Oxygen then moves from a region of high concentration to a region of lower concentration ~ out of the airspace in the lungs and into the blood.

The oxygen can then be carried from the lungs to tissues that need the oxygen to burn up fuel for energy.

Diffusion also takes away the waste carbon dioxide produced by this process. When carbon dioxide reaches the blood vessels around the airways of the lungs, it passes out of the blood and into the air, from a region of high concentration to a region of lower concentration. And then it is breathed out, ridding the body of this waste product.

Diffusion is essential, it's how the cell lives and breathes, gets nutrients, oxygen. There are two sub-types of diffusion through the cell membrane, simple diffusion and facilitated diffusion. In facilitated diffusion molecules are assisted by carrier proteins, often against an energy gradient so the process needs an additional source of energy over and above the kinetic energy required for simple diffusion.

It is important way by which substances move in and out of the cells.