Zusammenfassung der Ressource
Diffusion
- Villi in the small
intestine
- wall just one cell thick -
ensures that there is only a
short distance for absorption
to happen by diffusion and
active transport.
- Increased
surface area to
absorb more
nutrients.
- Gas exchange in the lungs
- Large surface area
- many alveoli are
present in the lungs
with a shape that
further increases
surface area.
- Thin walls - alveolar walls are
one cell thick providing gases
with a short diffusion
distance.
- Extensive blood supply -
ensuring oxygen rich blood
is taken away from the
lungs and carbon dioxide
rich blood is taken to the
lungs
- A large diffusion gradient -
breathing ensures that the
oxygen concentration in the
alveoli is higher than in the
capillaries so oxygen
moves from the alveoli to
the blood. Carbon dioxide
diffuses in the opposite
direction.
- gills of fish
- large surface area
of the gills
- large surface
area of the
blood
capillaries in
each gill
filament
- the short distance
required for diffusion –
the outer layer of the
gill filaments and the
capillary walls are just
one cell thick
- there is a counter
current flow of
water and blood
- roots and leaves in
plants
- large surface area
- Thin leaves minimize the
diffusion pathway
- Amoeba
- large surface
area
- Thin cell membrane to
create a thinner diffusion
pathway