Overview of the Normal Structure and Function of the Macrocirculation and Microcirculation

Nichols, Wilmer W.; Heffernan, Kevin S.; Chirinos, Julio A.

doi:10.1007/978-3-319-14556-3_2

Cited by 4 publications

(2 citation statements)

References 202 publications

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“…1 Our circulatory system is primarily comprised of two interconnected subsystems with varied functionality: macrocirculation, i.e., blood flows through large elastic arteries and transports oxygen and metabolites, and microcirculation, i.e., nutrient-rich blood flows from the left ventricle to the small arteries such as prearterioles, arterioles, and capillaries, which help in distributing blood to the organs and body tissues. 7 Normal blood is a highly complicated, viscoelastic and thixotropic, non-Newtonian fluid consisting of blood cells suspending in plasma (a Newtonian fluid, with a typical viscosity of about 1.2 mPa s at 37 ○ C 8 ) composed mostly of water and proteins. In addition to RBCs, blood cells include white blood cells and platelets, with RBCs consisting the vast majority (by ∼98%); thus, the rheology of blood is primarily determined by the rheological behavior of RBCs.…”

Section: Introductionmentioning

confidence: 99%

A constitutive hemorheological model addressing both the deformability and aggregation of red blood cells

Stephanou

2020

Physics of Fluids

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Red blood cells (RBCs) in physiological conditions are capable of deforming and aggregating. However, both deformation and aggregation are seldom considered together when modeling the rheological behavior of blood. This is particularly important since each mechanism is dominant under specific conditions. To address this void, we herein propose a new model that accounts for the deformability of red blood cells, by modeling them as deformed droplets with a constant volume, and of their aggregation, by properly characterizing the network formed by red blood cells under small shear rates. To derive the model, we employ non-equilibrium thermodynamics that allows us to consistently couple the two mechanisms and guarantees model admissibility with the thermodynamic laws. Relative to our previous model, which addresses the rheological behavior of non-aggregating deformable red blood cells, one additional structural variable, λ, to properly characterize the network formed by RBCs, and another additional parameter, ε, that quantifies the relative importance between the regeneration/buildup and flow-induced breakup of the network, are considered here. The new model predicts a yield shear stress, in accord with experimental data, but also predicts non-vanishing yield normal stresses. Although no rheological measurements of yield normal stresses of blood have been reported in the literature, the recent measurement of yield normal stresses of other yield stress fluids indicates their potential existence in blood as well. We show that the new model is in complete accord with the experimental rheological behavior of normal blood in both steady-state and transient (step-change in shear-rate) simple shear.

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Section: Introductionmentioning

confidence: 99%

A constitutive hemorheological model addressing both the deformability and aggregation of red blood cells

Stephanou

2020

Physics of Fluids

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“…In the present hemodynamic model of microcirculation, only the resistance element for a vessel segment was considered. Although in the microcirculation the resistance element plays a dominant role in hemodynamics ( Katanov et al, 2015 ; Nichols et al, 2015 ; Secomb, 2017 ) and the results show that the model is sufficient for produce varying blood flow distribution in a tree, a comprehensive model is worth being introduced in the future study.…”

Section: Discussionmentioning

confidence: 99%

Development of Novel Fractal Method for Characterizing the Distribution of Blood Flow in Multi-Scale Vascular Tree

Pan

Jiang

et al. 2021

Front. Physiol.

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Blood perfusion is an important index for the function of the cardiovascular system and it can be indicated by the blood flow distribution in the vascular tree. As the blood flow in a vascular tree varies in a large range of scales and fractal analysis owns the ability to describe multi-scale properties, it is reasonable to apply fractal analysis to depict the blood flow distribution. The objective of this study is to establish fractal methods for analyzing the blood flow distribution which can be applied to real vascular trees. For this purpose, the modified methods in fractal geometry were applied and a special strategy was raised to make sure that these methods are applicable to an arbitrary vascular tree. The validation of the proposed methods on real arterial trees verified the ability of the produced parameters (fractal dimension and multifractal spectrum) in distinguishing the blood flow distribution under different physiological states. Furthermore, the physiological significance of the fractal parameters was investigated in two situations. For the first situation, the vascular tree was set as a perfect binary tree and the blood flow distribution was adjusted by the split ratio. As the split ratio of the vascular tree decreases, the fractal dimension decreases and the multifractal spectrum expands. The results indicate that both fractal parameters can quantify the degree of blood flow heterogeneity. While for the second situation, artificial vascular trees with different structures were constructed and the hemodynamics in these vascular trees was simulated. The results suggest that both the vascular structure and the blood flow distribution affect the fractal parameters for blood flow. The fractal dimension declares the integrated information about the heterogeneity of vascular structure and blood flow distribution. In contrast, the multifractal spectrum identifies the heterogeneity features in blood flow distribution or vascular structure by its width and height. The results verified that the proposed methods are capable of depicting the multi-scale features of the blood flow distribution in the vascular tree and further are potential for investigating vascular physiology.

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Family patterns of arterial stiffness across three generations in the Malmö Offspring Study

Rosberg

Nilsson²

2020

Journal of Hypertension

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Background: Central haemodynamics have in recent years emerged as a promising predictor of cardiovascular health and risk of cardiovascular disease (CVD). Central haemodynamics are affected early in the development of vascular aging and contributes to target organ damage. Carotid–femoral pulse wave velocity (c-f PWV), augmentation index (Aix) and central SBP (cSBP) are variables that reflect arterial stiffness and central haemodynamics. Aim: To study the association between patterns of central haemodynamics across three related generations focusing on c-f PWV. Methods: In all, 1131 participants from the Malmö Diet Cancer Study (MDCS) and Malmö Offspring Study (MOS) were included. c-f PWV was measured (Sphygmocor) in grandparents and in all offsprings. Correlation analyses of c-f PWV between offspring and c-f PWV in parents and grandparents were conducted. Parents and grandparents were stratified into quartiles by c-f PWV. Offspring c-f PWV means were compared with one-way ANOVA analyses. Multiple regression analyses were adjusted for age, sex, BMI, SBP and fasting glucose. Bonferroni corrections were used. Results: c-f PWV in offsprings was positively correlated with c-f PWV in parents (r = 0.26, P < 0.001) and in grandparents (r = 0.29, P < 0.001). Parents with high c-f PWV had offspring with significantly higher means of c-f PWV. Conclusion: A measure of aortic stiffness (c-f PWV) is positively correlated across three related generations in this population-based study.

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Overview of the Normal Structure and Function of the Macrocirculation and Microcirculation

Cited by 4 publications

References 202 publications

A constitutive hemorheological model addressing both the deformability and aggregation of red blood cells

A constitutive hemorheological model addressing both the deformability and aggregation of red blood cells

Development of Novel Fractal Method for Characterizing the Distribution of Blood Flow in Multi-Scale Vascular Tree

Family patterns of arterial stiffness across three generations in the Malmö Offspring Study

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