adaptations for gas exchange (3.1) Flashcards
what is the relationship between the size of and organism and its surface area and volume ratio
smaller organisms have a large sa to v ratio , larger organisms have a smaller sa to v ratio
what is the impact of smaller organisms having a larger surface area to volume ratio
they have a large surface to exchange substances but also a short distance between the outside and the middle of the organism so they can just use simple diffusion for gas exchange
how do larger organisms achieve gas exchange
they have specialised exchange surfaces as simple diffusion would take too long
what are some features of an specialised gas exchange surface
-large sa
-short diffusion pathway
-maintenance of concentration gradient
do larger or smaller organisms have a higher metabolic rate
smaller organisms because they have a larger sa to v ratio they loose heat more easily so use up more energy to maintain their body temperature
what do insects have to prevent water loss
-waterproof exoskeleton
-spiricles that can close
-small sa to v ratio water can evaporate from
describe an insects tracheal system
-spiracles run along the abdomen allowing o2 and co2 to enter and leave, they attach to the trachea
-trachea are a network of internal tubes held open by rings
-the trachea branch into tracheoles which extend throughout the tissue to deliver co2 and o2 to respiring cells
how can insects use diffusion for gas exchange
as cells respire they use up o2 and release co2 this creates a conc gradient from the tracheoles to the atmosphere
how can insects move gases on mass
by contracting and relaxing their abdominal muscles
how do insects move gas when in flight
-in flight insects muscle cells start to anaerobically respire which produces lactate
-this lowers the water potential of the cells
-so water moves in from the tracheoles by osmosis
-this decreases volume in the tracheoles so more air is drawn in from the atmosphere
why do fish require an exchange surface (gills)
-they are waterproof
-small sa to v ratio
how do you calculate the rate of diffusion using flicks law
sa X diff in conc/length of diffusion path
describe the gills
-made up of stacks of gill filaments
-these gill filaments are covered in gill lamellae
-creating a large sa
how are the gill lamellae adapted for exchange
-thin
-surrounded by capillary network
-large sa
what is the countercurrent flow
water flows over the gills in the opposite direction to blood flow in the capillaries
