B8-exchange and transport in animals Flashcards
example of organisms exchanging substances with their environment
cells-they need oxygen for aerobic respiration.which produces CO2 as a waste product.both gasses move between cells + environment by diffusion
how easy it is for an organism to exchange substances with its environment depends on the what?
surface are to volume ratio (SA:V)
the larger an organism is…
the smaller its surface area is compared to its volume
surface are equation
length x width
volume equation
length x width x height
what do you do to get the ratio into the form n:1
divide both sides by the volume
why can gasses and dissolved substances diffuse in or out of single celled organisms across the membrane
they have a large surface area compared to their volume->enough substances can be exchanged across the membrane to supply the volume of the cell
multicellular organisms(such as animals)
have smaller surface area compared to their volume->makes it difficult to exchange enough substances to supply their entire volume across their outside surface alone. meaning they need some sort of exchange surface
what are alveoli
an exchange surface found in the lungs of mammals
3 main things that the rate of diffusion depends on
Distance-substances diffuse quicker when they haven’t as far to move
concentration difference(gradient)-substances diffuse faster if theres a big concentration gradient between area there diffusing from and to.(if a lot more particles on one side there are more to move across
surface area-more surface area there is the faster they can get from one side to another
whats the job of the lungs
transfer oxygen to the blood and remove waste carbon dioxide from it
what do lungs contain
millions of little air sacs(alveoli) where gas exchange takes place
where has the blood come from when its just arrived at the alveoli
the rest of the body(so it has lots of co2 and not much 02 which maximises the concentration gradient for diffusion of both gasses)
what does oxygen do
diffuses out of the air in alveoli(where the concentration of 02 is high) and into the blood(where concentration of 02 is low)
what does co2 do
diffuses in the opposite direction to be breathed out
how are alveoli specalised to maximise diffusion
-moist lining for dissolving gasses
-good blood supply to maintain concentration gradients
-very thin walls-minimising the distance that gasses have to move
-enomours surface area
whats does ficks law describe
the rate of diffusion
ficks law equation
rate of diffusion(proportional to/fish sign)surface area x concentration difference over thickness of membrane
if the surface area or difference in concentration doubles what happens to the tickness of membrane
it halves
what is one of the main jobs of blood
a transport system
what do red blood cells carry
oxygen
where do red blood cells carry oxygen to
from the lungs to all cells in the body
physical factors/adaptations of red blood cells
biconcave disc-to give a large surface area for absorbing oxygen
dont have a nucleus-allows more room to carry oxygen
what do red blood cells contain
haemoglobin(a pigment that contains iron)
