ventilation:exhalation
INternal inters contract ribs puled DOWN diaphragm RELAXES, domeand out increases thorax capacity decreased volume = decreased pressure atmospheric pressure higher so gradient made air flows into lungs down pressure gradient
gas exchange adaptations in plants
-short diffusion pathway of leaves-selectively permeable cell surface membrane -large SA of leaves so many stomata-movement of external O2-movement of internal CO2 for photosynthesis and maintained gradient
Transpiraton
evaporation of water from the stomata of a plants leaves
adaptations of xerophytes
waxy cuticle- waterproof reduces evaporation, increases diffusion distance guard cells- close to prevent water loss, minimise surface areaspines not leaves less stomata sunken stomata and hairs, curled leaves - traps vapor, increases humidity, reduce WP gradient shallow roots- absorb surface water
insect tracheal system adaptations
-external medium- abdominal pumping, muscular contractions, for ventilation - maintains O2 gradient -short diffusion pathway- tracheoles branch deep to tissue, O2 closer, faster diffusion -external medium -air at spiracles maintains O2 gradient for aerobic respiration-selectively permeable - allows CO2 O2 to freely diffuse -large surface area- spiracles, tracheoles branched
waterloss adaptions in insects
waxy exoskeleton spiracles close close independently only open when CO2 critical sunken spiracles, traps moisture, reducing the WP gradient
gas exchange in fish
counter current blood and water flow blood always in direct contact with water and higher concs of O2 so diffusion across whole length of lamellae
adaptations of fish gills
-internal medium- circulation replaced O2 rich blood-counter current flow maintains con along whole gill-short diffusion pathway - thin epithelium H2O to O2-ventilation forces O2 saturated water over gill-selectively permeable for CO2 O2 diffusion - many filaments and lamellae large surface area
human gas exchange :TRACHEABRONCHI ALVEOLI
Bronchi:prevent from collapsing when air pressure falls alveoli:elastic fibres- stretch and recoil
effective gas exchange
ventilation - contractions of diaphragm bring in air to maintain CO2 O2 diffusion gradients thin walls selectively permeable
ventilation :Inspiration
EXternal inters contract ribs puled UP and out diaphragm contracts, domesdecreases volume of thorax decreased volume = increased pressure atmospheric pressure lower so gradient made air flows out of lungs down pressure gradient