scholarly journals The liver, a functionalized vascular structure

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sylvie Lorente ◽  
Mathieu Hautefeuille ◽  
Aczel Sanchez-Cedillo
Keyword(s):  
Blood Flow ◽  
Liver Blood Flow ◽  
The Body ◽  
Toxic Substances ◽  
Porous System ◽  
Design Evolution ◽  
Multi Scale ◽  
Geometrical Features ◽  
The One ◽  
Good Agreement

Abstract The liver is not only the largest organ in the body but also the one playing one of the most important role in the human metabolism as it is in charge of transforming toxic substances in the body. Understanding the way its blood vasculature works is key. In this work we show that the challenge of predicting the hepatic multi-scale vascular network can be met thanks to the constructal law of design evolution. The work unveils the structure of the liver blood flow architecture as a combination of superimposed tree-shaped networks and porous system. We demonstrate that the dendritic nature of the hepatic artery, portal vein and hepatic vein can be predicted, together with their geometrical features (diameter ratio, duct length ratio) as the entire blood flow architectures follow the principle of equipartition of imperfections. At the smallest scale, the shape of the liver elemental systems—the lobules—is discovered, while their permeability is also predicted. The theory is compared with good agreement to anatomical data from the literature.

NON-INVASIVE LIVER BLOOD FLOW ASSESSMENT DEVICE

2020 ◽  
pp. 141-146
Author(s):  
Мария Рашитовна Ахмедзянова ◽  
Александр Викторович Кобелев ◽  
Александр Петрович Николаев ◽  
Аза Валерьевна Писарева
Keyword(s):  
Blood Flow ◽  
Liver Blood Flow ◽  
Current Source ◽  
Electrical Current ◽  
The Body ◽  
Toxic Substances ◽  
Negative Consequences ◽  
Tissue Impedance ◽  
Non Invasive ◽  
Method Of Evaluation

Клетки печени наиболее подвержены отрицательным последствиям, т.к. печень принимает активное участие в обменных процессах и в выведении из организма вредных и токсичных веществ. С появлением методов исследования, позволяющих изучать локальный кровоток в различных отделах печени, значительно увеличились возможности распознавания патологии. Реогепатография позволяет оценить функциональное состояние сосудов печени, их тонус, эластичность и кровенаполнение, объемную скорость кровотока и выявить застойные явления в венах. Целью данной статьи являлась разработка технического проекта по созданию прибора для неинвазивной оценки кровотока печени. Разработанный прибор оценивает кровоток печени по изменению ее удельного сопротивления. Метод оценки - электроимпедансная реогепатография. Данный метод позволяет регистрировать динамические изменения в импедансе ткани, вызванные изменениями кровотока печени в период сердечного цикла при пропускании через ткань электрического тока высокой частоты и малой амплитуды. Предложена оптимальная конструкция реографа, состоящего из системы электродов, источника тока, биоусилителя, системы сбора данных и блока питания. Электродная система состоит из 6 электродов (2 токовых и 4 измерительных). Портативный прибор позволяет измерять импеданс в диапазоне 0-250 Ом Liver cells are most exposed to negative consequences, because the liver takes an active part in metabolic processes and in the removal of harmful and toxic substances from the body. With the introduction of research methods that allow the study of local blood flow in different parts of the liver, the ability to recognize pathology has increased significantly. Rheohepatography can assess the functional state of liver vessels, their tone, elasticity and blood flow, the volume rate of blood flow and to identify stagnation in the veins. The purpose of this article was to develop a technical project to create a device for non-invasive assessment of blood flow in the liver. The developed device evaluates blood flow of the liver by changing its resistivity. The method of evaluation is electroimpedance rheopathography. This method allows to register dynamic changes in tissue impedance caused by changes in blood flow of the liver during the cardiac cycle when passing through the tissue of high frequency and small amplitude electrical current. The optimal design of the rheograph, consisting of a system of electrodes, current source, bioamplifier, data acquisition system and power supply unit is proposed. The electrode system consists of 6 electrodes (2 current and 4 measurement electrodes). The portable device allows measuring impedance in the range of 0-250 Ohm

scholarly journals Calculating the optimal hematocrit under the constraint of constant cardiac power

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michal Sitina ◽  
Heiko Stark ◽  
Stefan Schuster
Keyword(s):  
Blood Flow ◽  
High Performance ◽  
Animal Species ◽  
Normal Values ◽  
Mechanical Load ◽  
The Body ◽  
Trade Off ◽  
Cardiac Power ◽  
Optimal Value ◽  
Good Agreement

AbstractIn humans and higher animals, a trade-off between sufficiently high erythrocyte concentrations to bind oxygen and sufficiently low blood viscosity to allow rapid blood flow has been achieved during evolution. Optimal hematocrit theory has been successful in predicting hematocrit (HCT) values of about 0.3–0.5, in very good agreement with the normal values observed for humans and many animal species. However, according to those calculations, the optimal value should be independent of the mechanical load of the body. This is in contradiction to the exertional increase in HCT observed in some animals called natural blood dopers and to the illegal practice of blood boosting in high-performance sports. Here, we present a novel calculation to predict the optimal HCT value under the constraint of constant cardiac power and compare it to the optimal value obtained for constant driving pressure. We show that the optimal HCT under constant power ranges from 0.5 to 0.7, in agreement with observed values in natural blood dopers at exertion. We use this result to explain the tendency to better exertional performance at an increased HCT.

Attached cavitation and the boundary layer: experimental investigation and numerical treatment

1985 ◽  
Vol 154 ◽  
pp. 63-90 ◽  
Author(s):  
J. P. Franc ◽  
J. M. Michel
Keyword(s):  
Boundary Layer ◽  
Leading Edge ◽  
The Body ◽  
Numerical Treatment ◽  
Laminar Separation ◽  
Complete Calculation ◽  
Detachment Criterion ◽  
Continuous Curvature ◽  
The One ◽  
Good Agreement

Attached cavitation on a wall with continuous curvature is investigated on the basis of experiments carried out on various bodies (circular and elliptic cylinders, NACA 16 012 foil). Visualization of the boundary layer by dye injection at the leading edge shows that a strong interaction exists between attached cavitation and the boundary layer. In particular, it is shown that the cavity does not detach from the body at the minimum pressure point, but behind a laminar separation, even in largely developed cavitating flow. A detachment criterion which takes into account this link between attached cavitation and boundary layer is proposed. It consists of connecting a cavitating potential-flow calculation and a boundary-layer calculation. Among all the theoretically possible detachment points, the actual detachment point is chosen to be the one for which the complete calculation predicts a laminar separation just upstream. This criterion, applied to the NACA foil, leads to a prediction which is in good agreement with experimental results.

scholarly journals Some Observations on Cyanosis

1904 ◽  
Vol 24 ◽  
pp. 393-399
Author(s):  
G. A. Gibson
Keyword(s):  
Blood Flow ◽  
Specific Gravity ◽  
Alimentary Tract ◽  
Venous Blood ◽  
Constant Factor ◽  
The Body ◽  
The Other ◽  
General Terms ◽  
Circulatory Disorders ◽  
The One

The one constant factor in the production of cyanosis is diminution of oxygenation. This may be the result of respiratory affections which hinder the access of air or diminish the area of the aerating surface, or it may, on the other hand, be due to circulatory disorders lessening the amount of the blood flowing to the lungs. These latter affections furnish the most conspicuous examples of cyanosis, and in them the symptom is entirely produced by hindrance to the blood flow. Such is in reality the original conception advanced by Morgagni and supported by numerous observers. The other view, apparently suggested by Corvisart, that the condition is due to admixture of arterial and venous blood, is absolutely untenable, as in the vast majority of cases there is no possibility of such intermingling. In general terms the blood in cyanosis may be said to be of high specific gravity—from 1070 to 1080. The amount of hæmoglobin rises considerably—often reaching above 100 per cent. The erythrocytes increase in number so as frequently to exceed 7,500,000 per cubic millimetre, while the leucocytes, although not so commonly altered in number, often reach such a figure as 12,000 per cubic millimetre. The increase of these constituents of the blood was first observed by Toeniessen. Malassez showed that there are more red corpuscles in the blood of the superficial than of the deeper parts of the body. Toeniessen and Penzoldt suggested that this might be due to loss of fluid from the surface, while the interior receives a constant supply of fluid from the alimentary tract.

scholarly journals Current concepts of the role of fiber in the bird

2021 ◽  
Author(s):  
T.M. Okolelova ◽  
S.V. Engashev
Keyword(s):  
The Body ◽  
Biologically Active ◽  
Metabolic Energy ◽  
Toxic Substances ◽  
Natural Sorbent ◽  
Nutritional Factors ◽  
Alternative Sources ◽  
The One ◽  
Different Sources

Realization of the genetic potential of poultry productivity in industrial poultry farming is achieved by creating optimal conditions for keeping poultry and providing it with compound feeds, balanced in terms of metabolic energy and a complex of nutrient, mineral and biologically active substances. Fiber has always been and remains among the standardized indicators in mixed feed for poultry, since its excessive amount in a number of feed products (hulled crops, bran, sunflower meal, cake, etc.) is associated with a reduced digestibility of nutrients and energy availability). It is believed that fiber maintains the balance of the intestinal microflora, stimulates the growth of the muscular stomach and motility of the digestive tract, being a natural sorbent, absorbs toxic substances and ensures normal digestion and absorption of nutrients in feed. Despite the fact that the presence of fiber in compound feed for poultry is inevitable, the opinion of experts on its benefits differs.On the one hand, leading breeding companies and scientists consider fiber to be a necessary component for the development of the gizzard in order to stimulate the consumption of compound feed. On the other hand, poultry nutritionists try not to overload diets with fiber, especially if they consist of components that are difficult to hydrolyze, as this reduces the energy value of the diet. In addition, wastes from flour and fat-and-oil industries are often associated with such disadvantages as increased bacterial contamination or mycotoxin contamination. There is another controversial point that different sources of fiber have different effects on the digestive system, which is associated with the presence of anti-nutritional factors in the feed that affect its solubility. The review of publications provides information on the role of insoluble fiber in the body of poultry and its traditional and alternative sources.

Liver Blood Flow as a Major Determinant of the Clearance of Recombinant Human Tissue-Type Plasminogen Activator

1992 ◽  
Vol 67 (01) ◽  
pp. 083-087 ◽  
Author(s):  
A de Boer ◽  
C Kluft ◽  
J M Kroon ◽  
F J Kasper ◽  
H C Schoemaker ◽  
...  
Keyword(s):  
Blood Flow ◽  
Rat Liver ◽  
Healthy Subjects ◽  
Liver Blood Flow ◽  
Major Determinant ◽  
Tissue Type ◽  
Perfused Rat Liver ◽  
Liver Model ◽  
Type Plasminogen Activator ◽  
Proportional Change

SummaryThe influence of changes in liver blood flow on the clearance of rt-PA was studied both in healthy subjects and in a perfused rat liver model. Liver blood flow in healthy subjects was documented indirectly by the clearance of indocyanine green (ICG). Exercise reduced liver blood flow on average by 57% with a 95% confidence interval (95% Cl) ranging from 51% to 62% (n = 5) and increased plasma levels of rt-PA activity (after an i. v. infusion of 18 mg of rt-PA over 120 min) by 119% (95% Cl, 58% - 203%) and rt-PA antigen by 91% (95% Cl, 30% - 140%). In the perfused rat liver model it was shown that halving or doubling of the physiological flow rate of a perfusate, containing rt-PA caused a proportional change in the clearance of rt-PA, while the extraction of rt-PA by the liver remained similar. In conclusion, liver blood flow is a major determinant of the clearance of rt-PA. This may have important implications for dosage of rt-PA in patients with myocardial infarction.

COMPARISON OF ANTIHYPERTENSIVE EFFECT OF MOXONIDINE VERSUS CLONIDINE IN RENAL FAILURE PATIENTS.

2018 ◽  
Vol 6 (9) ◽  
Author(s):  
DR.MATHEW GEORGE ◽  
DR.LINCY JOSEPH ◽  
MRS.DEEPTHI MATHEW ◽  
ALISHA MARIA SHAJI ◽  
BIJI JOSEPH ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Renal Failure ◽  
Blood Flow ◽  
Blood Vessel ◽  
Blood Vessels ◽  
High Blood Pressure ◽  
Antihypertensive Effect ◽  
The Body ◽  
Ability To Work ◽  
Blood Flows

Blood pressure is the force of blood pushing against blood vessel walls as the heart pumps out blood, and high blood pressure, also called hypertension, is an increase in the amount of force that blood places on blood vessels as it moves through the body. Factors that can increase this force include higher blood volume due to extra fluid in the blood and blood vessels that are narrow, stiff, or clogged(1). High blood pressure can damage blood vessels in the kidneys, reducing their ability to work properly. When the force of blood flow is high, blood vessels stretch so blood flows more easily. Eventually, this stretching scars and weakens blood vessels throughout the body, including those in the kidneys.

‘If you shoulder a rifle […] let it be for Ireland’: James Connolly's War on War

2018 ◽  
Vol 13 (3) ◽  
pp. 364-381
Author(s):  
Margot Gayle Backus ◽  
Spurgeon Thompson
Keyword(s):  
World War I ◽  
The Body ◽  
Party Leader ◽  
Irish Nationalism ◽  
British Imperialism ◽  
Communications Networks ◽  
Easter Rising ◽  
Trade Unionist ◽  
The One ◽  
National Governments

As virtually all Europe's major socialist parties re-aligned with their own national governments with the outbreak of World War I, Irish socialist and trade unionist James Connolly found himself internationally isolated by his vociferous opposition to the war. Within Ireland, however, Connolly's energetic and relentless calls to interrupt the imperial transportation and communications networks on which the ‘carnival of murder’ in Europe relied had the converse effect, drawing him into alignment with certain strains of Irish nationalism. Connolly and other socialist republican stalwarts like Helena Molony and Michael Mallin made common cause with advanced Irish nationalism, the one other constituency unamenable to fighting for England under any circumstances. This centripetal gathering together of two minority constituencies – both intrinsically opposed, if not to the war itself, certainly to Irish Party leader John Redmond's offering up of the Irish Volunteers as British cannon fodder – accounts for the “remarkably diverse” social and ideological character of the small executive body responsible for the planning of the Easter Rising: the Irish Republican Brotherhood's military council. In effect, the ideological composition of the body that planned the Easter Rising was shaped by the war's systematic diversion of all individuals and ideologies that could be co-opted by British imperialism through any possible argument or material inducement. Although the majority of those who participated in the Rising did not share Connolly's anti-war, pro-socialist agenda, the Easter 1916 Uprising can nonetheless be understood as, among other things, a near letter-perfect instantiation of Connolly's most steadfast principle: that it was the responsibility of every European socialist to throw onto the gears of the imperialist war machine every wrench on which they could lay their hands.

Immunological mechanisms of chronic liver lesions under the influence of chemicals

2020 ◽  
pp. 536-537
Author(s):  
G. S. Agzamova ◽  
M. M. Abdullaeva
Keyword(s):  
The Body ◽  
Chronic Liver ◽  
Toxic Substances ◽  
Liver Lesions ◽  
Industrial Chemicals ◽  
Toxic Agent ◽  
Chronic Poisoning ◽  
Immunological Mechanisms ◽  
T System

The immunological profile of chronic liver lesions depending on the toxic agent was studied. It was revealed that chronic poisoning by industrial toxic substances causes changes in the functional state of the T-system of immunity, long-term contact with industrial chemicals leads to increased sensitization to autoantigens of the body.

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