Placenta does 3 things:
- Attaches foetus
- Removes waste
- Supplies nutrients
The difference in levels is the concentration gradient – this difference allows diffusion to happen.
Nutrients and waste products are free to diffuse from one blood supply to another, but maternal and foetal blood never mixes.
Adaptations of the Placenta –
- The exchange of waste and nutrients happen because of the difference (concentration gradient) of the two substances.
- These substances diffuse across the villi of the placenta
- Villi have large surface area for more area for diffusion and is very close to the bloodstream
This is a paper 2, triple science fact