Maksym G N, Fredberg J J, Bates J H
Harvard School of Public Health, Physiology Program, Boston, Massachusetts 02115, USA.
J Appl Physiol (1985). 1998 Oct;85(4):1223-9. doi: 10.1152/jappl.1998.85.4.1223.
We have developed a model of forces developed in lung tissue in which the stress-bearing units are heterogeneous. Each element of the fiber network is composed of an idealized elastin and collagen element in parallel. Elastin is represented by linear springs and collagen by stiff strings that extend without resistance until taut. The model can quantitatively account for the nonlinear shape of the length-tension curve of lung tissue strips when the knee lengths of the collagen fibers are distributed according to an inverse power law. The novel feature of this model is that as macroscopic strain increases the load is carried by progressively fewer elements with progressively higher forces, and preferential pathways of force transmission emerge within the matrix. The topology of these self-organizing pathways of force transmission takes the rough appearance of cracks, but, unlike real cracks, they represent the locus of force concentration rather than force release.
我们构建了一个肺组织中力产生的模型，其中承受应力的单元是异质的。纤维网络的每个元素由理想化的弹性蛋白和胶原蛋白元素并联组成。弹性蛋白由线性弹簧表示，胶原蛋白由刚性弦表示，刚性弦在拉紧之前无阻力地伸展。当胶原纤维的拐点长度根据反幂律分布时，该模型可以定量解释肺组织条带长度-张力曲线的非线性形状。该模型的新颖之处在于，随着宏观应变增加，承载负荷的单元逐渐减少，而力逐渐增大，并且在基质内出现了优先的力传递途径。这些自组织的力传递途径的拓扑结构呈现出类似裂纹的粗糙外观，但与真实裂纹不同的是，它们代表的是力集中的位置而非力释放的位置。
