scholarly journals Investigation of blood flow and the effect of vasoactive substances in cutaneous blood vessels of Xenopus laevis

2015 ◽  
Vol 39 (2) ◽  
pp. 91-95 ◽  
Author(s):  
Aleš Škorjanc ◽  
Gregor Belušič
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Circulatory System ◽  
Skin Patch ◽  
Vasoactive Substances ◽  
Functional Differences ◽  
Receptor Blockers ◽  
Internal Side ◽  
Arteries And Veins ◽  
Cutaneous Blood

In the present study, a preparation of frog skin was presented, which can be used to demonstrate the basic concepts of blood flow regulation in a very clear and attractive way to high school and university students. In a freshly euthanized Xenopus, a patch of abdominal skin was exposed from the internal side and viewed with a USB microscope while it remained connected to a functioning circulatory system. In this way, it was possible to obtain sharp images of arteries and veins and to visualize blood flow. This allows students to learn about the functional differences between arteries and veins and about the complexity of hemodynamics as well as the particularities of the amphibian pulmocutaneous circulation. Students can then quantitatively estimate the effect of norepinephrine and epinephrine on the diameter of blood vessels by simply superfusing the skin patch with a series of solutions of the two substances. They can also test the effect of α-adrenergic receptor blockers, used to treat high blood pressure, on the norepinephrine-induced muscle tonus of blood vessels.

scholarly journals A laboratory exercise using a physical model for demonstrating countercurrent heat exchange

2012 ◽  
Vol 36 (1) ◽  
pp. 58-62
Author(s):  
Catherine Loudon ◽  
Elizabeth C. Davis-Berg ◽  
Jason T. Botz
Keyword(s):  
Blood Flow ◽  
Heat Exchange ◽  
Blood Vessels ◽  
Physical Model ◽  
Circulatory System ◽  
Concentration Gradients ◽  
Laboratory Exercise ◽  
Permeable Barrier ◽  
Countercurrent Exchange ◽  
Physical Principles

A physical model was used in a laboratory exercise to teach students about countercurrent exchange mechanisms. Countercurrent exchange is the transport of heat or chemicals between fluids moving in opposite directions separated by a permeable barrier (such as blood within adjacent blood vessels flowing in opposite directions). Greater exchange of heat or chemicals between the fluids occurs when the flows are in opposite directions (countercurrent) than in the same direction (concurrent). When a vessel loops back on itself, countercurrent exchange can occur between the two arms of the loop, minimizing loss or uptake at the bend of the loop. Comprehension of the physical principles underlying countercurrent exchange helps students to understand how kidneys work and how modifications of a circulatory system can influence the movement of heat or chemicals to promote or minimize exchange and reinforces the concept that heat and chemicals move down their temperature or concentration gradients, respectively. One example of a well-documented countercurrent exchanger is the close arrangement of veins and arteries inside bird legs; therefore, the setup was arranged to mimic blood vessels inside a bird leg, using water flowing inside tubing as a physical proxy for blood flow within blood vessels.

scholarly journals Functional hierarchy of coronary circulation: direct evidence of a structure-function relation

2005 ◽  
Vol 289 (6) ◽  
pp. H2559-H2565 ◽  
Author(s):  
Ghassan S. Kassab
Keyword(s):  
Blood Flow ◽  
Structure Function ◽  
Blood Vessels ◽  
Direct Evidence ◽  
Abrupt Change ◽  
Coronary Circulation ◽  
Arterial Tree ◽  
Functional Differences ◽  
Functional Hierarchy ◽  
Function Relation

The heart muscle is nourished by a complex system of blood vessels that make up the coronary circulation. Here we show that the design of the coronary circulation has a functional hierarchy. A full anatomic model of the coronary arterial tree, containing millions of blood vessels down to the capillary vessels, was simulated based on previously measured porcine morphometric data. A network analysis of blood flow through every vessel segment was carried out based on the laws of fluid mechanics and appropriate boundary conditions. Our results show an abrupt change in cross-sectional area that demarcates the transition from epicardial (EPCA) to intramyocardial (IMCA) coronary arteries. Furthermore, a similar pattern of blood flow was observed with a corresponding transition from EPCA to IMCA. These results suggest functional differences between the two types of vessels. An additional abrupt change occurs in the IMCA in relation to flow velocity. The velocity is fairly uniform proximal to these vessels but drops significantly distal to those vessels toward the capillary branches. This finding suggests functional differences between large and small IMCA. Collectively, these observations suggest a novel functional hierarchy of the coronary vascular tree and provide direct evidence of a structure-function relation.

scholarly journals Ear skin optical clearing for improving blood flow imaging/Optisches Clearing der Ohrhaut zur verbesserten Bildgebung des Blutflusses

2013 ◽  
Vol 2 (1) ◽  
Author(s):  
Jing Wang ◽  
Rui Shi ◽  
Yang Zhang ◽  
Dan Zhu
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Imaging Techniques ◽  
Flow Distribution ◽  
Optical Methods ◽  
Optical Clearing ◽  
Mouse Ear ◽  
Tumor Studies ◽  
Imaging Depth ◽  
Cutaneous Blood

AbstractVarious optical imaging techniques have shown a great potential for monitoring angiogenesis, development of blood vessels, and even tumor transfer, but they suffer from the limited imaging depth in tissue. Although the mouse ear provides an available window, the residual scattering of ear skin still influences the imaging quality. The proposed tissue optical clearing technique presents a new opportunity to decrease the scattering of skin, and enhance the imaging contrast or imaging depth of optical methods. The purpose of this study is to develop an innovative ear skin optical clearing agent (ESOCA) for improving the transparency of the mouse ear.The ESOCA was topically applied on the ear skin of BALB/c miceThe transmittance of mice ear was enhanced by 111.0±8.2% at 633 nm after application of ESOCA. The cutaneous blood vessels and blood flow could be distinguished more clearly with LSCI technique. In addition, the calculated CNR values of speckle contrast images showed a great enhancement compared with the initial (control) values.In summary, topical application of an innovative ESOCA permits the vessel structure and flow distribution information of cutaneous blood vessels to be imaged by LSCI with higher contrast, which will be significant for tumor studies in the future.

The development of ultrasound in vascular disease in Sweden

2011 ◽  
Author(s):  
Tomas Jogestrand ◽  
Olav Thulesius
Keyword(s):  
Blood Flow ◽  
Vascular Disease ◽  
Blood Vessels ◽  
Peripheral Blood ◽  
Clinical Information ◽  
Peripheral Circulation ◽  
Peripheral Blood Flow ◽  
Flow Measurements ◽  
Blood Flow Measurements ◽  
Arteries And Veins

The famous British scientist Sir Cyril A. Clarke in 1975 wrote the introduction for a new book, Arteries and Veins , with the following words: . . . In spite of all advances, mortality remains a steady 100 per cent and it is disorders of the arteries and veins which claim the majority of us. we sclerose, we clot, arrhythmias hit us, or our tubing wears out. By way of consolation, however, more of us now go the way of all flesh properly diagnosed and there are many ways of cheating the ancient enemy. . . . Clark at the time did not realize what advances were ahead of him, and the book he introduced with these dark lines included a chapter by R.G. Gosling and D.H. King which described a new promising technique of ultrasound angiography. Cyril Clark himself died at the age of 93! Blood flow measurements during resting conditions fail to detect any reduction of volume flow in patients with occlusive vascular disease, therefore for quantitative evaluation of the functional capacity of the peripheral circulation various functional tests implying increased circulatory demands needed to be introduced. The most useful clinical information could be obtained from peak-flow values after a period of obstruction and exercise followed by volume plethysmographic measurements of blood flow. Olav Thulesius introduced a foot ergometer in 1963 which allowed detection of maximal blood flow after graded muscular exercise. Its use was complicated and time-consuming when applied in conjunction with blood flow measurements with a water-filled volume plethysmograph. Therefore a faster and easier method for determination of peripheral blood flow was desirable. In 1967, the ultrasound scanning method for the detection of arterial blood flow signals in the diagnosis of fetal life during pregnancy was introduced in Sweden. This same principle became the method for detecting blood flow in peripheral blood vessels. The method used was a hand-held instrument which included two piezoelectric elements, one to transmit ultrasound signals and the other to receive the returning echoes back-scattered from the blood vessels. The instrument used for the detection of peripheral blood flow was the same as that for the detection of the fetal blood flow in pregnancy.

scholarly journals Structural and Functional Differences Between Porcine Aorta and Vena Cava

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Jeffrey M. Mattson ◽  
Yanhang Zhang
Keyword(s):  
Treatment Options ◽  
Vena Cava ◽  
Circulatory System ◽  
Vascular Wall ◽  
Multiphoton Imaging ◽  
Functional Differences ◽  
Low Levels ◽  
And Function ◽  
The Relationship ◽  
Arteries And Veins

Elastin and collagen fibers are the major load-bearing extracellular matrix (ECM) constituents of the vascular wall. Arteries function differently than veins in the circulatory system; however as a result from several treatment options, veins are subjected to sudden elevated arterial pressure. It is thus important to recognize the fundamental structure and function differences between a vein and an artery. Our research compared the relationship between biaxial mechanical function and ECM structure of porcine thoracic aorta and inferior vena cava. Our study suggests that aorta contains slightly more elastin than collagen due to the cyclical extensibility, but vena cava contains almost four times more collagen than elastin to maintain integrity. Furthermore, multiphoton imaging of vena cava showed longitudinally oriented elastin and circumferentially oriented collagen that is recruited at supraphysiologic stress, but low levels of strain. However in aorta, elastin is distributed uniformly, and the primarily circumferentially oriented collagen is recruited at higher levels of strain than vena cava. These structural observations support the functional finding that vena cava is highly anisotropic with the longitude being more compliant and the circumference stiffening substantially at low levels of strain. Overall, our research demonstrates that fiber distributions and recruitment should be considered in addition to relative collagen and elastin contents. Also, the importance of accounting for the structural and functional differences between arteries and veins should be taken into account when considering disease treatment options.

scholarly journals A Hydrodynamic Approach To Cancer

2015 ◽  
Author(s):  
Alexander Pinkowski ◽  
Walter Lilienblum
Keyword(s):  
Mass Transfer ◽  
Blood Flow ◽  
Blood Vessels ◽  
Tumor Cells ◽  
Circulating Tumor Cells ◽  
Apparent Viscosity ◽  
Food Supply ◽  
Circulatory System ◽  
Nutrient Supply ◽  
Hydrodynamic Approach

Abstract This is the pre-print version of a paper submitted to Technische Mechanik (ISSN 0232-3869) Hydrodynamic analysis suggests that the injection of drag-reducing agents (DRA) in nanomolar concentrations may hinder metastasizing of circulating tumor cells and serve this way as a complementary post-operative treatment for cancer patients. Our conclusion is based on the following considerations: - Tumor cells need an extra nutrient supply in order to survive and grow. - The attachment of circulating tumor cells therefore tends to occur at sites in the human circulatory system characterized by localized turbulence, which enhances the mass transfer of nutrients, e.g., at sites of vessel branching and bending with plasma skimming. - Also obstacles to blood flow, such as plaques (atherosclerosis), tumors, and red blood cell (RBC) rouleaux, produce local vortices that increase mass transfer, i.e., food supply. - DRA have the ability to smooth (laminarise) localized turbulence in the circulatory system and to reduce mass transfer. - Depriving tumor cells of their required nutrient levels will reduce the probability of creating metastatic tumors, and may lead to their starvation-induced death. In the first part of our essay we demonstrate how flow constrictions decrease mean blood flow velocity, wall shear rates, and Reynolds numbers respectively, and increase the friction factor. Experimentally derived apparent viscosity data from literature will be used to determine the probability of RBC rouleaux formation. This is of importance since RBC rouleaux are typically associated with turbulent blood flow patterns. An increase in apparent viscosity at low flow rates will be attributed to the formation of RBC rouleaux. In part two we discuss the application of the Lockhart/Martinelli method to determine the pressure drop in blood vessels. The objective is to determine a mass transfer coefficient characterizing the mass transfer between the center and the wall of both healthy and cancerous blood vessels. This coefficient indicates the nutrient supply available to tumor cells under different flow conditions and shows the effect of DRA. Our hydrodynamic approach contrasts with previous studies of the possible benefits of DRA injection, which were focused on improving blood supply. We emphasize the reduction of the mass transfer rate as a tool to withhold turbulence induced supplementary food supply to tumor cells. Due to the possibility of unexpected side effects when using DRA (including their mechanical degradation products) animal models are indispensable before clinical trials.

Innervation of endoneurial microvessels in human sural nerve

1992 ◽  
Vol 50 (1) ◽  
pp. 920-921
Author(s):  
John L. Beggs ◽  
Peter C. Johnson ◽  
Astrid G. Olafsen ◽  
C. Jane Watkins
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Blood Supply ◽  
Peripheral Nerves ◽  
Sural Nerve ◽  
Nerve Fibers ◽  
Arterial Supply ◽  
Autonomic Nerve ◽  
Vasa Nervorum ◽  
Endoneurial Blood Flow

The blood supply (vasa nervorum) to peripheral nerves is composed of an interconnected dual circulation. The endoneurium of nerve fascicles is maintained by the intrinsic circulation which is composed of microvessels primarily of capillary caliber. Transperineurial arterioles link the intrinsic circulation with the extrinsic arterial supply located in the epineurium. Blood flow in the vasa nervorum is neurogenically influenced (1,2). Although a recent hypothesis proposes that endoneurial blood flow is controlled by the action of autonomic nerve fibers associated with epineurial arterioles (2), our recent studies (3) show that in addition to epineurial arterioles other segments of the vasa nervorum are also innervated. In this study, we examine blood vessels of the endoneurium for possible innervation.

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.

The Vasostimulant Effect of the Electric Pulse Stimulator on the Cutaneous Blood Flow.

1997 ◽  
Vol 59 (2) ◽  
pp. 255-256
Author(s):  
Yuka NAKAMURA ◽  
Shinichi WATANABE ◽  
Hisashi TAKAHASHI ◽  
Atsuhiko HASEGAWA
Keyword(s):  
Blood Flow ◽  
Electric Pulse ◽  
Cutaneous Blood Flow ◽  
Cutaneous Blood
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