Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration.
Examples in our body:
1) In our lungs:
- Oxygen from alveoli to blood vessels
- Carbon dioxide from blood vessels to alveoli
2) In our tissues:
- Oxygen from capillaries to respiring cells
- Carbon dioxide from respiring cells to capillaries
- Glucose from capillaries to respiring cells
Osmosis is the movement of water molecules from a region of higher concentration to a region of lower concentration through a partially permeable membrane.
Osmosis occurs wherever there is movement of water molecules in our body.