Why does oxygen move from the alveoli into the pulmonary capillary blood?

Partial pressure of oxygen inside the alveolus is higher than in pulmonary capillary vessels, that allows oxygen molecules to diffuse into the blood.  

1) the mayans built pyramids just like the egyptians. the mayans also used hieroglyphics like them.2) power was passed down by family. for example, if the father dies, the son would be the next king.3)they both built pyramids for their structures.4)the main crop for the mayans was maize.5)they also grew manioc, beans,  squash,  amaranth, and chile peppers.

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