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How is blood oxygenated in the lungs?


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September 05, 2008 3:17PM

The operating principle is a process called diffusion, which causes a substance to move from a region of high concentration to a region of lower concentration. Think of a squirt of perfume diffusing from a corner in a room until you can smell it everywhere in the room. Blood returning from the body to the lungs has a higher percentage of carbon dioxide (CO2) than the air inhaled into the lungs does. Conversely the concentration of oxygen (O2) in the inhaled air is greater than the concentration of O2 in the returning blood. Haemoglobin, which can (loosely) bond to both O2 and CO2, facilitates the exchange of gasses from respective regions of high concentration to the regions of lower concentration. Specifically, CO2 moves from the returning blood (higher concentration) to the air in the lungs (lower concentration) and oxygen moves in the other direction, thus oxygenating the blood.