We know that blood contains hemoglobin, which contains iron atoms. In the lungs, there is a lot of oxygen available, which bonds with the hemoglobin. So blood leaving the lungs through the pulmonary veins—the only veins to carry oxygenated rather than deoxygenated blood—returns to the heart high in oxygen content and bright red in color. The heart pumps this red blood to the rest of the body through arteries to deliver oxygen to tissues, organs, and muscles, where it is used up. The blood returning in a separate set of veins is depleted of oxygen, which has been replaced with plenty of carbon dioxide, giving the blood a much darker red color. And when we look at our veins, the color of the blood appears bluish because some of the dark red color is absorbed by the veins and skin. (This only works for veins because we can’t actually see our arteries through our skin; they have muscular walls that are much thicker than our more thin-walled veins.) Mostly blue color is transmitted.
Answers
Ashish Koul
We know that blood contains hemoglobin, which contains iron atoms. In the lungs, there is a lot of oxygen available, which bonds with the hemoglobin. So blood leaving the lungs through the pulmonary veins—the only veins to carry oxygenated rather than deoxygenated blood—returns to the heart high in oxygen content and bright red in color. The heart pumps this red blood to the rest of the body through arteries to deliver oxygen to tissues, organs, and muscles, where it is used up. The blood returning in a separate set of veins is depleted of oxygen, which has been replaced with plenty of carbon dioxide, giving the blood a much darker red color. And when we look at our veins, the color of the blood appears bluish because some of the dark red color is absorbed by the veins and skin. (This only works for veins because we can’t actually see our arteries through our skin; they have muscular walls that are much thicker than our more thin-walled veins.) Mostly blue color is transmitted.