Point:Counterpoint: Gravity is/is not the major factor determining the distribution of blood flow in the human lung.
Point:Counterpoint: Gravity is/is not the major factor determining the distribution of blood flow in the human lung.
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观点：对立点：重力是/不是决定人体肺部血流分布的主要因素。
DOI：
10.1152/japplphysiol.90402.2008
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Prisk,GKim
中科院分区：
文献类型：
--
作者：
Hopkins,SusanR;Prisk,GKim
Glenny asserts that sagging of parenchyma near the base and corresponding stretching at the apex (in the upright lung) accounts for much of the total vertical perfusion gradient, because, due to sagging, there are more alveoli in a given field of view in basal than apical regions. He claims that this must be corrected for so as to obtain the effect of gravity independent of this (gravitationally induced) tissue movement. Thus, after tissue-sagging contributions to the vertical gradient are removed, what is left as a gradient is implied to be the real effect of gravity, and this is what Glenny considers. I have great trouble with this logic. Gravitationally induced tissue sagging is a fundamental part of how gravity affects perfusion (and, for that matter, ventilation) distribution. Deducting that component is tantamount to eliminating a major, real gravitational influence on perfusion distribution. Of course this “correction” must diminish the residual apex to base gradient. My point is that Glenny’s removal of the saggingrelated gravitational component is inappropriate in this debate because it is an important effect of gravity. What Hughes and West (2) describe is the total effect of gravity without such “corrections,” and that is what Glenny should be comparing his data with and basing his conclusions on.
