Word: oxygenate
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Emphysema results in slow smothering since it destroys the inner walls of lungs and hampers the exchange of carbon dioxide for oxygen in the blood...
...third line of evolution. It also provides an important clue to the earth's early environment. Scientists have long believed that for about the first billion years after the formation of the earth, the atmosphere consisted largely of hydrogen, carbon dioxide and other gases, but virtually no free oxygen. The life-style and genetic structure of Woese's archaebacteria tend to support the theory; because the strange bugs now live only in remote, airless niches of the environment and die when exposed to free oxygen, they may be little different today from ancestors that evolved in the oxygenless...
Then how and when did free oxygen begin appearing in the atmosphere? A clue to the answer has been found in the incredibly old sedimentary rocks of South Africa's eastern Transvaal by Harvard's Elso Barghoorn and Andrew Knoll, now with the Oberlin College department of geology. To the naked eye, the 3.5 billion-year-old rocks Barghoorn and Knoll collected during a visit last year revealed no traces of early life. But the scientists soon uncovered the stones' secrets. Returning to Harvard with samples of the rock, the pair used a diamond cutter...
Barghoorn and Knoll believe that their primitive fossils-the oldest direct evidence of terrestrial life-are the ancestors of modern blue-green algae or photosynthetic bacteria, both of which convert carbon dioxide into food and oxygen. If they are correct, these organisms 3.5 billion years ago were already pumping into the atmosphere the oxygen upon which most of today's terrestrial life now depends...
...reason, says Nemiroff, is a combination of coldness, which lowers the body's need for oxygen, and an old mammalian response known as the diving reflex. The reflex was studied in the 1930s in diving mammals, like the porpoise and seal, which can remain submerged without breathing for periods of 20 minutes or more. And, confirms Nemiroff, the same automatic response works in humans as well. Triggered by held breath and cold water on the face, the diving reflex slows the heartbeat and the flow of blood to the skin, muscles and other tissues that are relatively resistant...