Dipartimento di Matematica e Informatica "Ulisse Dini", Universitá degli Studi di Firenze, Viale Morgagni 67/a, 50134 Firenze, Italy.
Dipartimento di Matematica e Informatica "Ulisse Dini", Universitá degli Studi di Firenze, Viale Morgagni 67/a, 50134 Firenze, Italy; FIAB S.p.A., Vicchio, Firenze, Italy; I.A.S.I. - C.N.R., Via dei Taurini, Roma, Italy.
J Theor Biol. 2022 Jul 7;544:111124. doi: 10.1016/j.jtbi.2022.111124. Epub 2022 Apr 14.
We consider the flow of blood, treated as an incompressible Newtonian fluid, through vessels undergoing periodic oscillations. As remarked by many authors, in the absence of valves oscillations hinder the flow because of the lumen reduction. The underlying biological mechanism is the so-called vasomotion, observed long ago in small blood vessels. Here, we study the vasomotion in arterioles and provide its theoretical justification by analyzing the effect when the network of vessels downstream of the arterioles is considered. We thus explain both quantitatively and qualitatively, why the oscillations of the arteriole walls, a phenomenon that undoubtedly reduces blood flow at the level of the single arteriole, play a fundamental role in microcirculation. In "large" arterioles we analyze also the coupling between the vasomotion and the Fåhræus-Lindqvist effect (the tendency of the erythrocytes to accumulate towards the center). In particular, we prove that the presence of a cell depleted layer close to the vessel walls mitigates the disadvantage caused by the lumen reduction.
我们研究了在血管周期性振荡过程中血液的流动，将血液视为不可压缩的牛顿流体。正如许多作者所指出的，在没有瓣膜的情况下，由于管腔缩小，振荡会阻碍血液流动。潜在的生物学机制是所谓的血管舒缩运动，很久以前就在小血管中观察到。在这里，我们研究了小动脉中的血管舒缩运动，并通过分析小动脉下游血管网络的影响来为其提供理论依据。因此，我们从定量和定性两个方面解释了为什么小动脉壁的振荡——这一现象无疑会降低单个小动脉水平的血流——在微循环中起着至关重要的作用。我们还分析了大血管中的血管舒缩运动与 Fåhræus-Lindqvist 效应（红细胞倾向于向血管中心聚集）之间的耦合。特别是，我们证明了靠近血管壁的细胞耗竭层的存在减轻了管腔缩小带来的不利影响。
