All gas exchanges are made by the process of ___1___. When substances pass in this manner,
they move from areas of their ___2___ to areas of their ___3___. Thus, oxygen continually
passes from the ____4___ and then from the ___5____. Conversely, carbon dioxide moves from
the ___6____ and from ____7____. From there it passes out of the body during expiration. As a
result of such exchanges, most arterial blood tends to have ____8____ while most venous blood
has
_____9___