Where do the red blood cells pick up oxygen and drop off carbon dioxide? What system is this part of?

IN THE LUNGS, THE RED BLOOD CELLS IN BLOOD DROP OFF CARBON DIOXIDE TO THE AIR IN THE ALVEOLI (BY A PROCESS CALLED DIFFUSION) AND PICK UP OXYGEN FROM THE AIR IN THE ALVEOLI. IN THE CAPILLARIES, THE RED BLOOD CELLS DROP OFF OXYGEN TO THE BODY'S CELLS AND PICK UP CARBON DIOXIDE FROM THE CELLS.

Explanation:

d.

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