organism exchange Flashcards
surface area to volume ratio
larger the organism= smaller SA:V
Fick’s law is…
rate of diffusion= (SA x difference in conc.)/ length of diffusion path
single celled organisms…
exchange gases across body due to large SA:V
the tracheal system of insects has…
trachea
tracheoles
spiracles
adaptation of insect tracheal system…
gases enter + exit through spiracles
gas exchange through diffusion, CO2 conc. gradient from tracheoles to atmosphere
mass transport- contraction of abdominal muscles moves gases along
in flight, muscle cells respire anaerobically to produce lactate, lowering WP so water moves from tracheoles to cells
more air drawn down in to decreases volume in tracheoles
structure of mass exchange in fish
gill filaments (at right angles to each other to increase SA)
lamellae in gill filaments (deep folds= increases SA)
adaptation of gas exchange in fish are…
lamellae are folded for large SA
lamellae + filaments= thin, increased diffusion rate
use counter current exchange to absorb O2
counter-current principal is…
water and blood flow in opposite direction
ensures a favourable conc/ gradient of O2 is maintained across WHOLE LENGTH of lamellae
dicotyledonous plants…
exchange gas though stomata
guard cells control opening/closing, helps prevent water loss by evaporation
small SA:V
waxy cuticle (waterproof)
hairy leaves trap water vapour (reduce WP gradient)
cuticle rolls to cover stomata
structure of gas exchange in humans
trachea
bronchus
bronchiole
alveolus
diaphragm
lungs
ribs
inspiration
external intercostal muscle contracts, internal intercostal muscle releases
ribs pulled upwards and outwards whilst diaphragm contracts and flattens
increased thoracic volume, decreasing air pressure so air forced into lungs
expiration
external intercostal muscle relaxes, internal intercostal muscle contracts
ribs pulled downwards and inwards, diaphragm relaxes and is pushed back into dome shape
decreases thoracic volume, increasing air pressure so CO2 is forced into atmosphere
alveoli has…
very large SA= higher rate of diffusion
network of capillaries so short diffusion distance
alveolar epithelium is thin
amylase is…
produced in salivary glands/pancreas (secrets into the small intestine)
hydrolyses starch into maltose
membrane bound disaccharides…
present in membrane small intestine
hydrolyse disaccharides (maltose to monosaccharide like glucose)
lipase…
hydrolysis lipids to monoglycerides and fatty acids
present in small intestine