Where does diffusion take place in the body?

The process of diffusion takes place all over the body. It is a vital process for the body to maintain the environment in which the cells and organs work. For instance when food is digested and the nutrients that are needed for the normal functioning of the cells are released, they are carried around in the bloodstream until they reach a needy cell whereupon the nutrients diffuse from an area of high concentration (blood stream) to an area of low nutrient concentration (the cell). The medicines that we take are also absorbed in the same way and take effect after a process of diffusion.

Diffusion in the lungs. In the lungs, the blood will continue to take in oxygen from the alveolar air spaces, provided there is more oxygen in the air spaces than in the blood.