Diffusion Diffusion - Overview Diffusion in Human Body Systems Surface Area to Volume Ratio

Diffusion

Diffusion - Overview

The process where stuff goes from where there is more of it to where there is less until a balance is reached.

Diffusion is a passive process. The stuff just moves where it has to move.

This balance is called homeostasis.

Diffusion in Human Body Systems

We have studied diffusion in a number of systems:

The absorption of nutrients in the small intestine (through the villi -- see The Digestive System).

The exchange of gases in the lungs (through alveoli -- see The Respiratory System) and into the blood (through capillaries - see The Circulatory System).

The filtering of toxins from the blood in the kidneys (through the nephrons -- see The Excretory System).

Surface Area to Volume Ratio

All of these examples of diffusion involve making the Surface Area to Volume Ratio as big as possible.