Alveolar surface forces and lung architecture
Alveolar surface forces and lung architecture
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DOI：
10.1016/s1095-6433(01)00315-4
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发表时间：
2001-05-01
影响因子：
2.3
通讯作者：
Schürch, S
中科院分区：
文献类型：
--
作者：
Bachofen, H;Schürch, S
整个肺泡表面衬有一层薄薄的液体连续体。因此，在气液界面的表面力是有效的，其中一部分被传递到脆弱的肺组织。肺的形态学和形态计量学分析表明，肺泡表面力对肺泡组织元素有塑造作用。特别是，肺在低充气程度时，相当于正常呼吸的容积范围，肺泡表面积减少，表面张力增加，这反映了周围空气空间的平衡构型，其中组织能和表面能的总和最小。因此，表面张力的变化通过使肺组织变形从而改变组织张力，直接或间接地改变肺的反冲压力。然而，组织和表面力之间的相互作用是相当复杂的，表面力的成形影响有明显的体积依赖性。随着肺容量的增加，肺纤维支架传递的组织力成为肺泡微观力学的主要因素：当肺容量达到肺活量的80%或更高时，肺泡表面积-体积关系在很大程度上与表面张力无关。最重要的是，在正常呼吸的范围内，表面张力及其变化和相关的表面积变化很小。表面力的成型能力也影响毛细血管的结构，从而影响游离细胞成分（如表面衬里层下的肺泡巨噬细胞）和周围气道表面的微循环。肺泡流体与气道之间的耦合机制仍然是一个谜，这可能对肺泡清除也很重要。对于外围空气空间的表面活动衬层。由于膜的保存和固定问题，其结构和结构功能关系仍不明确。肺泡组织的电子显微照片，捕获气泡衬里层的电子显微照片，以及转移到云母板上的表面活性剂薄膜的扫描力显微照片，揭示了一个复杂的结构模式，迄今为止排除了明确假设的制定。(C) 2001爱思唯尔科学公司版权所有。
The entire alveolar surface is lined by a thin fluid continuum. As a consequence, surface forces at the air-liquid interface are operative, which in part are transmitted to the delicate lung tissue. Morphologic and morphometric analyses of lungs show that the alveolar surface forces exert a moulding effect on alveolar tissue elements. In particular, in lungs at low degrees of inflation, equivalent to the volume range of normal breathing, there is a derecruitment of alveolar surface area with increasing surface tensions which reflects equilibrium configurations of peripheral air spaces where the sum of tissue energy and surface energy is minimum. Thus, changes in surface tension alter the recoil pressure of the lung directly and indirectly by deforming lung tissue and hence changing tissue tensions. However, the interplay between tissue and surface forces is rather complex, and there is a marked volume dependence of the shaping influence of surface forces. With increasing lung volumes the tissue forces transmitted by the fiber scaffold of the lung become the predominant factor of alveolar micromechanics: at lung volumes of 80% total lung capacity or more, the alveolar surface area-volume relation is largely independent of surface tension. Most important, within the range of normal breathing, the surface tension, its variations and the associated variations in surface area are small. The moulding power of surface forces also affects the configuration of capillaries, and hence the microcirculation, of free cellular elements such as the alveolar macrophages beneath the surface lining layer, and of the surfaces of the peripheral airways. Still enigmatic is the coupling mechanism between the fluid continua of alveoli and airways which might also be of importance for alveolar clearance. As to the surface active lining layer of peripheral air spaces. which determines alveolar surface tension, its structure and structure-function relationship are still ill-defined owing to persisting problems of film preservation and fixation. Electron micrographs of alveolar tissue, of lining layers of captive bubbles, and scanning force micrographs of surfactant films transferred on mica plates reveal a complex structural pattern which precludes so far the formulation of an unequivocal hypothesis. (C) 2001 Elsevier Science Inc. All rights reserved.