科學60秒:強大的人類竟不如小小鳥
來源：滬江聽寫酷
2011-11-22 10:00
整句或部分句子聽寫，均含標點，整句開頭要大寫。
[ 1 ] . But sometimes what makes you stronger can kill you, at least when it comes to blood clotting. [ 2 ] .
[ 3 ] But birds don’t have ‘em, nor do reptiles or fish. Instead, these critters have blood cells called thrombocytes, which are about twice the size of platelets. But is bigger necessarily better when it comes to clotting? Scientists took thrombocytes from parakeets and put them to the test. The work appears in the journal Blood. [Alec A. Schmaier et al., "Occlusive thrombi arise in mammals but not birds in response to arterial injury: evolutionary insight into human cardiovascular disease"]
[ 4 ] , in that blood exerts pressure on walls of blood vessels.
The results: parakeet thrombocytes don’t stick together like platelets do. [ 5 ]
Which means that mice may be more likely to survive a bloodletting-pecking. But birds are far less likely to suffer from the clot forming economy class syndrome—despite being frequent fliers.
【視聽版科學小組榮譽出品】
[ 1 ] . But sometimes what makes you stronger can kill you, at least when it comes to blood clotting. [ 2 ] .
[ 3 ] But birds don’t have ‘em, nor do reptiles or fish. Instead, these critters have blood cells called thrombocytes, which are about twice the size of platelets. But is bigger necessarily better when it comes to clotting? Scientists took thrombocytes from parakeets and put them to the test. The work appears in the journal Blood. [Alec A. Schmaier et al., "Occlusive thrombi arise in mammals but not birds in response to arterial injury: evolutionary insight into human cardiovascular disease"]
[ 4 ] , in that blood exerts pressure on walls of blood vessels.
The results: parakeet thrombocytes don’t stick together like platelets do. [ 5 ]
Which means that mice may be more likely to survive a bloodletting-pecking. But birds are far less likely to suffer from the clot forming economy class syndrome—despite being frequent fliers.
【視聽版科學小組榮譽出品】
They say what doesn't kill you makes you stronger.
Because the stickiness that allow platelets to heal your wounds also raises your risk of heart attack.
All mammals use platelets to help prevent blood loss after traumatic injury.
They focused their attention on birds because our feathered friends have a cardiovascular system much like our own,
They also don't block blood flow in the birds' arteries the same way that platelets do when they form clots in mice.
人們總說殺不死你的，能讓你更強大。但有時候，你卻可能死于一些令你強大的因素。至少就血液凝固這一人類優(yōu)勢來說，能證實這一觀點。因為粘稠的血小板不但能愈合我們?nèi)祟惖膭?chuàng)傷，同時也會增加我們患心臟病的危險。
所以哺乳動物在遭受創(chuàng)傷后都是依靠血小板來防止出血過多。但是鳥類、魚類以及爬行類動物沒有這一功能。它們體內(nèi)有一種凝血細胞，是我們血小板的兩倍大。但是不是凝血細胞越大，凝血效果就越好呢？科學家提取了鸚鵡體內(nèi)的凝血細胞，進行實驗。實驗結果刊登在‘Blood’這本期刊上。
科學家們之所以把注意力集中在了小鳥上，是因為在我們那長滿羽毛的朋友體內(nèi)，血液施加給血管壁的壓力我們?nèi)祟惖南嘞?。可以說我們有相似的心血管系統(tǒng)。
實驗的結果是：鸚鵡的凝血細胞不如我們?nèi)祟惖难“迥敲唇o力。它們也不能在鳥類的動脈中起到類似血小板在小白鼠體內(nèi)的凝塊作用。
ps： 簡單介紹一下“經(jīng)濟艙綜合征”，因長時間飛行后，腿部腫脹的癥狀。在經(jīng)濟艙中病發(fā)幾率更高，因為經(jīng)濟艙的狹小空間，使乘客的腿部長時間不能自由動彈。因此，血液容易積壓在腿部，增加了血塊凝結的可能性。