Gas Exchange in humans Essay - 638 Words.
Similar to mammals, birds have lungs, which are organs specialized for gas exchange. Oxygenated air, taken in during inhalation, diffuses across the surface of the lungs into the bloodstream, and carbon dioxide diffuses from the blood into the lungs and expelled during exhalation.
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Gas exchange structures increase the SA:Vol to ensure oxygen supply is sufficient to meet the organisms oxygen demands. It also ensures that carbon dioxide is released at a greater rate than it is produced (a build up of carbon dioxide within the cells would be toxic) As an organism increases in size its volume increases more rapidly than it's surface area.
Similar to mammals, birds have lungs, which are organs specialized for gas exchange. Oxygenated air, taken in during inhalation, diffuses across the surface of the lungs into the bloodstream, and carbon dioxide diffuses from the blood into the lungs, and is then expelled during exhalation.
In animals with a closed circulatory system (such as birds, mammals, reptiles, and some amphibians), gas exchange takes place across the capillaries. Remember that the capillaries are the smallest blood vessel and can be found near every cell in the body. With trillions of cells, that’s a lot of capillaries.
They also have a short diffusion pathway which further increases the gas exchange efficiency. The countercurrent flow maintains a high concentration gradient throughout, with the circulatory system moving the blood saturated with oxygen away with the ventilated water being replaced with new water, all to ensure gas exchange is effective and efficient.