Describe what the diffusion happening between an alveolus and a blood capillary

Blood which arrives in the lungs is deoxygenated. The air breathed into the alveoli in the lungs has a high oxygen concentration. The oxygen diffuses from a high oxygen concentration in the lung alveoli to a low oxygen concentration in the blood and its red blood cells. The blood then becomes oxygenated and is pumped to respiring cells. Deoxygenated blood arriving at the lung alveoli will have a higher concentration of carbon dioxide than the air in the lungs. This means that carbon dioxide will diffuse from a high carbon dioxide concentration to a low carbon dioxide concentration in the alveoli in the lungs and will then be breathed out out the lungs.