Question 2 • 26-27 Ignite Health Science Concepts - EL3602
The alveolar-capillary membrane is the very thin barrier between the air in the lung alveoli and the blood in nearby capillaries. Oxygen and carbon dioxide diffuse across this layer, so choice A, the layer of cells through which gases are exchanged, is correct. Cilia help move debris out of the airways, while arteries carry blood rather than serve as the exchange membrane.
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