4.2 Flashcards
surface area to volume ratio
a large surface area to volume ratio means a larger diffusion area so a faster rate of diffusion
factors affecting diffusion
surface area
concentration gradient
distance
human gas exchange system
cilia filters out dust on the nasal cavity
air moves down trachea into bronchi
into bronchioles in lung
then into the alveoli where gas exchange occurs
oxygen into blood CO2 out
-large surface area and short diffusion distance.
inhilation
active process
muscles (intercostal) contract
diaphragm lowered and flattened
rib up and out
volume increases
air moves in
exhalation
passive proccess
muscles (intercostal) relax
ribs move down and in
volume decreases so equilizes pressure
air forces out
insects gas exchange
spiracles- holes (that can open and close) along thorax and abdomen where gas enters and exits by diffusion
tracheae- large tubes directly into the body supported by rings(chitin) so they don’t collapse
tracheoles- smaller branches dividing off the tracheae
site of gas exchange
active insects
some have mechanical ventilation that pumps are into the spiricles so venticlation movments of the abdomen using thorax to maintain conc gradient
air sacs increase the volume of air moved and provide storage
collapsable trachea act as resivoirs (supply of oxygen)
fish gas exchange
water moves in through the mouth
this flows over the gills which have gil filaments which have gil lamelae which is the main site of gas exchange as it has a good blood suply
the water constantly flows as diffusion is slow
this then flows out through the operculum (the cover)
countercurrent exchange system
blood and water flows in opposite directions where the water has always got more oxygen than the blood to maintain a diffusion gradient along the whole lamella
alveoli adaptations
moist walls- disovles gasses easier
one cell thick- smaller diffusion pathway
rich blood suplier- steeper conc graident
fics law
rate of diffusion = (surface area x steepness of conc gradient ) // thickness of membrane
oxygen consumtion in mamals
lower body mass consume more o per kg
to regulate body temp
small mammals have a large surface area to volume ratio
as size increase sa to v decreases
so loose more heat by respiration
single cell organisms
no gas exchange system
large surface area to volume ratio
so dif is sufficient
gill adaptations
large SA-V ratio
thin for short diffusion distance
countercurrent
marram grass leaf adaptations
curved
-reduced conc gradient/trap water vapour
-less evaporation
stomata inside in pits
-reduce conc gradient
waxy cuticles reduces water loss
