2008年3月26日 星期三
Adaptation of Air Sacs for Gaseous Exchange
Adaptation for all transport :
1) large number of alveoli -> vary large surface area
2) thin layer of epidthellium -> short distance for diffusion
Adaptation for diffusion :
3) moist, covered by mucus -> dissolve and diffuse rapidly
4) covered by network of capillary -> oxygen can delivered to body rapidly , CO2 can delivered out the body rapidly, create steeply concentration gradient to fasten diffusion
5) low blood pressure in nearby capillary -> stay longer time for gaseous exchange
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