Topic 3 Flashcards
What is surface area vs volume?
surface area:total area which an organism is exposed to the external factors(outside environment)
Volume: the internal space
What 2 things effect how quickly substances are exchanged by organisms?
-size and surface area to volume ratio
What does a higher surface mean and what organsims have them?
-small organisms
-higher surface area: short diffusion path way between outside and inside environment
- fast metabolic rate
-
What does lower surface area mean?
- larger organism
-longer diffusion path between external and internal environment
-lose heat quicker- have adaptations
Where does gas exchange happen?
on a bondary between external and internal environment
what molecules diffuse through gas exchange surface?
carbon dioxide and oxygen
What 2 things cause an efficent gas exchange system
-higher surface area to volume ration
- ablilty to maintain a steep concentration gradient
Gas exchange in single cell organism
-not specialised (short diffusion path way)
-thin walls
-high surface area to volume ratio
-cell membrane
Why do fish require a gas excahnge system?
-low SA: V ratio
-attain oxygen through gills however ozygen in water is 10x less than it is in air
Properties of gills in a fish( how the make gas exchnge more efficent)
-each gil has gil filaments(increase SA)
-each filament has lamella(increase SA)
-lamella- many capillaries(near by blood supply) and a thin layer of cells( short diffusion path)
-have a countercurrent system
How does the countercurrent system help maintain a steep concentration gradient?
-blood flows ontop of water in the oppsite direction
How does the countercurrrent system work?
-deoxygenated blood enters lamellae
-water flows towards lamellae(high oxygen concentation)
-oxygenated blood exits lamellae
-water flows away from lamellae( low oxygen concetration)
what is the countercurrent principle/ mechanism?
blood flows in the opposite direction to water
lable a fish gil
what is an advantage of the counter current system?
allows for diffusion along the lamellae/gil filaments
