gas exchange Flashcards
size and structure to its surface area to volume ratio
as size increases sa v decreases
more thin and flat shape structure increases the surface area to volume ratio
what is the metabolic rate
amount of energy used by an organism in given time
it is often measured as oxygen uptake as its used in aerobic respiration to make atp for energy release
what is the relation ship between sa ato v ratio and the metabolic rate
as surface area to volume increases the metabolic rate increases
because the rate of heat loss per unit of body mass increases
so organisms needed higher rate of respiration - to release enough heat to maintain a constant body temperature
adaptations for exchange in a larger organism
long and thin body to reduce long diffusion pathway
specialised surfaces to maintain a concentration gradient for diffusion
how are single celled organisms adapted for gas exchange
thin flat shape so large SA:V
short diffusion distance to all parts of cell
describe the tracheal system of insets
spiracles - pores - open and close for diffusion
trachea - tubes full of air allow diffusion - branch into smaller tracheoles which are permeable to allow gas exchange in cells
how is the tracheal system adapted for gas exchange
tracheoles and lots of them have thin walls so short diffusion distance to cells meaning large SA
trachea- provides tubes full of air for fast diffusion
abdominal muscles contract changing pressure in the body causing air to move in and out and maintains a conc gradient for diffusion
how do teresstial insects limit water loss compromises
thick waxy cuticle increases the diffusion distance so less water loss
spiracles - open 4 gas exchange - close to reduce water loss
hairs around spiracles trap moist air reducing the WPG so less water loss
gills adaptation for gas exchange
gills - made of many filaments - covered in lamellae increase SA 4 DIFFUSION
thin lamellae wall so short diffusion distance between water and blood
lamellae have a large no of capillaries so remove o2 and bring co2 quick maintaining a conc gradient
counter current flow
blood and water flow in opposite directions over lamellae
so o2 conc in water higher than in blood near
maintain a conc gradient of o2 btwn water and blood
for diffusion along whole length of lamellae
if parallel flow equlib reached and oxygen wouldn’t diffuse into blood along whole length of gill plate
leave adaptations for gas exchange
many stomata - LSA 4 gas exchange
spongy mesophyll - contains air spaces LSA for gases to diffuse through
thin = short diffusion distance
xerophyte compromises to limit water loss
thick waxy cuticle increases the diffusion distance
sunken stomata in pits trap water vapour so reduce WPG `between leaf and are = less evaporates
spines reduce SA:V
alveolar epithelium and gas exchange
1 cell thick - short diffusion distance
folded for a large sa
permeable allows diffusion of o2/co2
most gases can dissolve for diffusion
good blood supply form large network of capillaries maintaing a conc gradient
how does gas exchange occur in lungs
oxygen diffuses from alveolar air space into blood down its conc gradient
across alveolar epthithelium then across capillary Endo
ventilation importance
bring in air containing high conc of o2 and remove air with low conc of o2
maintains a conc gradient
