gas exchange Flashcards
what is Ficks law?
rate of diffusion = SA x difference in conc. / thickness of diffusion barrier
what is the rate of diffusion dependent on?
- surface area
- diffusion pathway
- concentration gradient
how turbulence in water increase the rate of diffusion?
increases oxygenation in water and therefore the conc. gradient
why don’t amoeba (unicellular) require specialised gas exchange systems?
they have a high SA:V, so diffusion pathways are short. the gas exchange surface of amoeba is the cell membrane
why do flatworms (multicellular) not require specialised gas exchange systems?
they have a high SA:V, and their flat shape allows them to have a shirt diffusion pathway. Their gas exchange surface is their external body surface.
why do earthworms require a gas exchange system?
although its long cylindrical body allows it to have a high SA:V, the diffusion distance is too large for oxygen to supplied for its metabolic needs via diffusion alone.
how does the earthworm’s circulatory system supply oxygen to the tissues?
The blood vessels are close to the external surface for a short diff. pathway. Earthworms have a closed circulatory system. The blood contains haemoglobin that has a high affinity for oxygen.
what is the gas exchange surface of the earthworm?
external body surface
