2.2 - adaptations for gas exchange Flashcards
(55 cards)
give 2 examples of a respiratory surface in which gas exchange happens efficiently.
- gills of a fish
- alveoli in lungs of a mammal
what 4 features must an exchange surface have for it to be rapid diffusion?
- large SA to volume
- thin
- permeable
- have a mechanism to produce steep gradient across respiratory surface by bringing oxygen or removing co2
what is meant by a unicellular organism?
single-celled organism
single-celled organisms is very thin and has a large SA therefore they can do 2 things…?
- absorb enough oxygen to meet their needs
- remove co2 fast enough so it doesn’t build up a concentration which wold make the cytoplasm too acidic for enzymes to function
why are multicellular animals not efficient at gas exchange?
lower surface area to volume ratio - diffusion across surfaces is not efficient enough
name 3 features of a earthworm.
-low oxygen requirement - slow moving
-cylindrical shape so SA to volume ratio is smaller than flat
worms
-haemoglobin present in blood - carries oxygen around body in blood vessels
what 2 features do multicellular animals have that unicellular organisms don’t?
- higher metabolic rate
- more specialised cells, tissues and organs - therefore more interdependent
life on earth involved in water so what major problems may this have on terrestrial animals (entirely on land)?
-water evaporates from body surfaces - dehydration
where does gas exchange take place on a amphibian?
through the skin - moist, permeable and well developed capillary network
how do reptiles have an increased surface area for gas exchange?
lungs have a more complex internal structure
why do birds process large volumes of oxygen?
flight requires lots of oxygen
how do birds ventilate their lungs more efficiently compared to vertebrates?
do not have a diaphragm but their ribs and flight muscles help
what 2 features do gills have?
- one way current of water
- folds - provide large SA over which water can flow
what are the two types of fish - why are the different?
cartilaginous fish - skeleton of cartilage
bony fish- skeleton of bones
give an example of a cartilaginous fish and describe their gills
shark - 5 gills on each side
what are 2 reasons why cartilaginous fish’s ventilation system is less efficient than the bony fish?
- do not have special mechanism to force water out of gills
- blood travels same direction as water through the gill - PARALLEL FLOW - means only 50% of oxygen can diffuse
on a bony fish the gills are covered by what? what do the mean?
operculum- doesn’t open directly
what does ventilation allow?
maintains a continuous, unidirectional flow so water is forced over the gill filaments
in ventilation what is the mechanism that operates to take water in? 6 steps.
- mouth opens
- operculum closes
- floor of mouth is lowered
- volume inside of mouth cavity increases
- pressure inside mouth cavity decreases
- water flows in AS external pressure is higher tan the pressure inside mouth
in ventilation what is the mechanism that operates to force water out by the gills? 6 steps.
- mouth closes
- operculum closes
- floor of mouth raised
- volume inside the mouth cavity decreases
- pressure inside mouth cavity increases
- water flows out over gills AS pressure in mouth is higher than opercular
explain in terms of gills why fish die if they are out of water for more than a very short time.
gill plats are held apart by water flowing between them so out of water they stick together and gills collapse - less area exposed - not enough gas exchange can take place
describe what is meant by counter-current flow.
blood and water flow In opposite directions at the gill lamellae - maintains concentration gradient
what 3 things do gills provide for carbon dioxide exchange?
- a specialised respiratory surface
- a large surface extended by gill filaments and gill lamellae
- extensive network of blood capillaries
what is the air tight compartment the lungs are in?
the thorax
