Since ancient times, Tibetan people live in the roof of the world. Here the average altitude of up to 4,500 meters, the oxygen content in the air is also lower compared to the plains. Climbers from the plains must recognize this fact: As altitude increases, breathing will be more difficult, it will then nausea, dizziness and other symptoms, severe cases can even cause death. The latest research shows that Tibetan thicker arteries and capillaries, to deliver more oxygen to muscles and organs, so they will not altitude sickness.
Case Western Reserve University (Case Western Reserve University) anthropologist Cynthia Beall told us: "While living in extreme hypoxic plateau, but Tibetans consume oxygen and daily life in the plains of the people rather their velocity. almost twice the life of plain people, which makes them better able to adapt to high altitude. "
Tibetan intimal will produce large amounts of nitric oxide, nitric oxide diffusion into the blood, into nitrite and nitrate, making arteries and telangiectasia, and then increase blood flow, oxygen delivery faster whole body. Beall and his colleagues published in the "American Academy of Sciences" (PNAS) article reported: by measuring 85 and 50 living in the Tibetan plains forearm blood flow velocity Cleveland people, they found that the former velocity It is 2 times the latter, while Tibetan blood nitric oxide is a byproduct Cleveland 10 times.
In fact, the Tibetan blood nitrite and nitrate concentrations higher than patients with septic shock, their velocity is faster than in patients with hypertension, but these have no adverse effects on the Tibetan. Beall said that they did not detect increased vascular resistance. In addition, the concentration of Tibetans in vivo antioxidant is also higher, this may be reduced to nitric oxide as a free radical, the negative effects on the human body.
Moreover, Tibetan respiratory rate not only higher than people living in low altitudes, even higher than those living in the South American Andes, with great lung volume known people. While to the Tibetan inhaling pure oxygen, their heart rates will drop 16%. But the relevant researchers noted Tibetan body high concentrations of nitric oxide, the key is their adaptation to high altitude.
This can not help but speculate that this is not a feature of human evolution practical clues. Beall said: "Now it seems that this assumption is not unreasonable, but to prove it, but also to find the corresponding gene and its variants.."
Tibet towering, magnificent natural landscape and harsh living environment and to jointly develop majesty of nature. The two thousand years, but Tibetans stubbornly survive and thrive here. Beall said: "Born in the Tibetan plateau is human adaptation to high altitude environment typical of normal life in the area has such a high altitude, which they knew was special.."
(Written by: David Biello / David Biello translation: Lining Xi)
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