Bellwork Which blood vessels (all sizes) deliver blood to the lungs from the heart? Which take blood back to the heart from the lungs (all sizes)? What blood vessels are involved in gas exchange of O2 and CO2? How is the O2 converted to CO2?
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Alveoli spherical = large surface area capillary bed surrounding = gases do not diffuse far http://medicalterms.info/img/uploads/anatomy/alveoli-picture.gif
Alveoli single cell thickness = gases do not diffuse far moist lining of each alveolus = better diffusion of gases into and out of the blood http://yr8science2011.wikispaces.com/file/view/Alveolus-Natasha.JPG/246002109/316x325/Alveolus-Natasha.JPG