exchange surfaces Flashcards
why do large organisms need specialised exchange surfaces
small SA:V ratio
high metabolic activity
larger distance between supply and cells that need it
exchange + removal of substances
name features of a good exchange system
increased SA
thin layers
good blood supply
name and describe key features of human exchange sitem
nasal cavity
- large SA + good blood supply
- warms air to body temp
- hairy lining secretes mucus trapping dust+ bacteria
trachea
- airway from nose to chest
- incomplete rings of cartilage to stop collapsing and allow food movement down oesophagus behind it
- cilliated epithelium move mucus away
- goblet cells between epithelial cells secret mucus
bronchus
- trachea divides into left + right
- similar structure to trachea
bronchioles
- bronchi divide
- no cartelage
- smooth muscle in walls constricts to dilate bronchioles
alveoli
- tiny air sacs
- elastic tissue allows stretch
- increase SA of lungs
- thin layers + god blood supply
what happens during inspiration
energy requiring
diaphragm contracts
external intercorsal muscles contract -moves ribs up
thorax volume increases- pressure reduces
air drawn in through nasal passages to equalise pressure inside+ out
what happens during expiration
passive
diaphragm muscles relax- moves up
eternal intercorsa muscles relax- ribs move down
elastic fibres of alveoli return to normal length
thorax volume decreases
forcibly exhale= internal intercorsa muscles contract
name and describe components of lung volume
tidal volume= vol. that moves in with rising breath
vital capacity=max air in with deepest intake after deepest exhale
inspiratory reserve volume= max air can breathe in after normal inhale
expiratory reserve volume= extra air able to breathe out after normal exhale
residual vol= vol left in lungs after hardest exhale
total lung capacity=vital capacity+ residual vol
how is ventilation rate measured
total vol of air inhaled in 1 min
how is lung capacity measured
spirometer- measures aspects of lung volume + breathing patterns
peak flow meter- measures rate air can be expelled
how does gas enter insects
opening along thorax call SPIRACLES
opened/ closed by sphincters
kept closed as much as possible to reduce water loss
more spiracles opened when O2 demand rises
how does gas exchange occur in insects
tracheae lead away from spiracles
1mm in diameter
lines by spirals of chitin to keep them open- only relatively permeable
trachea branch to form tracheoles- not chitin
treacheoles permeable to gases
tracheal fluid at end
how do bony fish regulate blood flow over gills when they stop moving
mouth open- floor of buccal cavity is lowered
increases volume and decreases pressure so water moves in
opercular valve shut- opercular cavity containing gills expands
mouth closes
opercular valve opens
pressure increases
forces water over gills
how is the exchange system in bony fish effective
tips of adjacent gill filaments overlap
increase distance tofu of water slowing it down
more time for gas exchange
water flow over gills and blood travel in opposite directions
steeper conc grad at both ends
