HIGH IN THE SKY, MALLARD DUCKS, SWANS, VULTURES, OXYGEN, TIBET, ANDES MOUNTAINS, MIGRATIONS, INSPIRED AIR, INHALED AIR

HIGH IN THE SKY

Hi everyone! How has this past week been for you? Mine was a good one. As a matter of fact I just got off the phone with my daughter who lives in South Carolina. She told me she may be flying out to visit in a few weeks. It is always a pleasure to see any of my children!

Speaking of flying, have you ever thought much about flying? The airline companies do a good job of keeping us safe. They make the airplanes and jets arrow dynamic and provide pressurized cabins so we can breath at the high altitudes that planes travel in. The commercial airlines even provide

oxygen masks should the pressure in the cabins fail.

People and animals that are born and live in high altitude regions get or are used to such low oxygen levels. “The highest-lying permanent settlements, in the Andes and in Tibet, are situated at just above 5000 m. [16,400 feet]. Not even people belonging to these mountain communities would

be able to survive more than a few hours in the oxygen-deficient air above 8000 m. [26,200 feet]. The oxygen content of the air is about 21%, independent of altitude, in the troposphere; the oxygen pressure consequently decreases in parallel with the decreasing air pressure at increasing altitude. At 6000 m. [20,000 feet] the oxygen pressure is only half what it is at sea-surface level; at 8000 m. [26,200 feet] it is a third of that and at 10,000 m. [32,800 feet] only a quarter.”¹

But what about the high flying birds? “How can they survive elevations of 15,000 feet and sometimes higher without a

supplemental source of oxygen? Many bird migrations occur at extremely high elevations: 21,000 feet for the mallard duck, 27,000 feet for swans, even 36,000 feet for vultures!…How are birds able to breathe in such oxygen-starved conditions? What they have—thanks to their Creator—is much more efficient than Antis’ custom-made oxygen mask! A bird’s lungs function according to the

through-flow principle: the inspired [inhaled] air collects in the bird’s posterior air-sacs and flows through the lungs to the anterior air-sacs before it passes back out. In the lungs the blood is oxygenated by fine air capillaries, where air and blood flow in opposite directions. Owing to this counterflow, the oxygenated blood that leaves the bird lung acquires a higher oxygen concentration than that corresponding to the oxygen pressure in the expired [exhaled] air. In addition to flow-through lungs, birds have

hearts that are proportionately larger to their bodies than those of mammals—from 0.8 to 1.5% of total body mass, compared to mammals, which average around 0.6%. The birds’ larger hearts enable speedy blood transport and intensive oxygen renewal.”2

Oxygen masks and pressurized cabins in airplanes and jets