Gas exchange Flashcards
1
Q
Principles of gas exchange
A
- large S.A
- permeable
- moist
- short distance
- maintain steep diffusion gradient
- thin surface
2
Q
surface area + volume
A
- requirements proportional to size
- as organisms increase SA:V ratio decreases
3
Q
small organisms
A
- large SA:V ratio
- diffusion gradient enough to meet demand
4
Q
large organisms
A
- smaller SA:V ratio
- need special exchange and transport system
5
Q
terrestrial organisms
A
-internal lungs to minimise heat+water loss
- water evaporates from body surface (dehydrate)
- water fits through exchange surface so always moist
6
Q
amphibians
e.g frogs, toads
A
- aquatic larvae with gills
- adults use skin + lungs as surface
- active so need lungs
- skin (moist, permeable, well developed capillary network, respiratory pigment and circulatory system)
7
Q
fish
A
- water has less o2 than air
- gas exchange surface is gills
- large SA
- network of capillaries
- blood has haemoglobin for oxygen
8
Q
bony fish
-exchange system
A
- 4 gills each side supported by gill arch
- along arch are filaments (lamellae)
- lamellae increase SA
- when not in water lamellae stick together
9
Q
bony fish
-gills
A
- need large SA
- no gills (suffocate)
- ectotherms (handle low O2 environment)
10
Q
bony fish
-counter current and parallel flow
A
parallel flow
-less efficient (diffusion gradient favours water to blood which is only part across gill lamellae)
counter current
-efficient (water flows over gill lamellae in opposite direction to blood, equilibrium never reached)
