Microfluidics of blood in blood vessels stenosis

2016 ◽  
Vol 11 (2) ◽  
pp. 210-217 ◽  
Author(s):  
A.T. Akhmetov ◽  
A.A. Valiev ◽  
A.A. Rakhimov ◽  
S.P. Sametov ◽  
R.R. Habibullina
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Hydraulic Resistance ◽  
Microfluidic Device ◽  
Human Body ◽  
Vascular System ◽  
Hydrodynamic Conditions ◽  
Microstructure Change ◽  
Healthy Part

It is mentioned in the paper that hydrodynamic conditions of a flow in blood vessels with the stenosis are abnormal in relation to the total hemodynamic conditions of blood flow in a vascular system of a human body. A microfluidic device developed with a stepped narrowing for studying of the blood flow at abnormal conditions allowed to reveal blood structure in microchannels simulating the stenosis. Microstructure change is observed during the flow of both native and diluted blood through the narrowing. The study of hemorheological properties allowed us to determine an increasing contribution of the hydraulic resistance of the healthy part of the vessel during the stenosis formation.

Growth regulation of the vascular system: evidence for a metabolic hypothesis

1990 ◽  
Vol 259 (3) ◽  
pp. R393-R404 ◽  
Author(s):  
T. H. Adair ◽  
W. J. Gay ◽  
J. P. Montani
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Growth Regulation ◽  
Vascular System ◽  
Major Influence ◽  
Control Element ◽  
Hypoxic Conditions ◽  
Control Growth ◽  
Vessel Growth ◽  
Tissue Cells

Prolonged imbalances between the perfusion capabilities of the blood vessels and the metabolic requirements of the tissue cells often lead to modification of the vasculature to satisfy the tissue needs. This homeostatic response appears to be bidirectional, since the vascularity of a tissue can increase or decrease in parallel with primary changes in metabolic rate. The factors that mediate the responses are not well understood, but oxygen has been implicated as a major control element, since vessel growth increases during hypoxic conditions and decreases during hyperoxic conditions. The following feedback control hypothesis may apply to many different physiological situations. Decreased oxygenation causes the tissues to become hypoxic, and this initiates a variety of signals that lead to the growth of blood vessels. The increase in vascularity promotes oxygen delivery to the tissue cells by decreasing diffusion distances, increasing capillary surface area, and increasing the maximum rate of blood flow. When the tissues receive adequate amounts of oxygen even during periods of peak activity, the intermediate effectors return to normal levels, and this negative signal, in turn, stops the further development of the vasculature. Although the effector mechanisms of the hypoxic stimulus are still being investigated, adenosine, which is produced in hypoxic tissues, appears to mediate hypoxia-induced increases in vascularity in some instances. Roles for fibroblast growth factor as well as mechanical factors associated with vasodilation and increased blood flow are postulated. Although blood vessel growth is a multifactorial process, a major influence in its regulation appears to be metabolic need. If this view is correct, it may be found that many of the quantitatively significant factors that control growth in a given vasculature are themselves modulated or controlled by metabolic signals reflecting the nutritional status of the tissues which that vasculature supplies.

Collective methods of propulsion and steering for untethered microscale nanorobots navigating in the human vascular network

2010 ◽  
Vol 224 (7) ◽  
pp. 1505-1513 ◽  
Author(s):  
S Martel
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Human Body ◽  
Interventional Procedures ◽  
Vascular Network ◽  
Single Type ◽  
Tumour Targeting ◽  
Miniature Robots ◽  
Medical Diagnostic ◽  
Blood Flow Velocities

In the field of medical nanorobotics, nanometre-scale components and phenomena are exploited within the context of robotics to provide new medical diagnostic and interventional procedures, or at least to enhance the existing ones. The best route for such miniature robots to access various regions inside the human body is certainly the vascular network. Such a network is made of nearly 100 000 km of blood vessels varying in diameters from a few millimetres in the arteries down to ∼ 4 μm in the capillaries with respective important variations in blood flow velocities. When injected in the blood circulatory network using existing modern techniques such as catheterization, such robots must travel from larger-diameter vessels before reaching much tinier capillaries. As such, the use of a single type of microscale robots capable of travelling in various environments and conditions related to such different blood vessels while being trackable by an external system seems, at the present time, inconceivable. Therefore, as explained in this article, an approach based on the use of several types of microscale robots with complementary methods of propulsion and steering capable of operating in a collective manner is more likely to achieve better results. This is especially true for interventions such as direct tumour targeting where the tiniest blood vessels such as the ones found in the angiogenesis network must be travelled.

scholarly journals Treatment of Vasculitis: Beyond the Basics

2020 ◽  
Author(s):  
Muhammad Ishaq Ghauri ◽  
Muhammad Shariq Mukarram
Keyword(s):  
Blood Flow ◽  
Mycophenolate Mofetil ◽  
Blood Vessels ◽  
Human Body ◽  
Systemic Vasculitis ◽  
Organ Damage ◽  
Biological Agents ◽  
Cytotoxic Agents ◽  
Is Failure ◽  
Primary Vasculitis

Vasculitis is the inflammation of blood vessels in the human body. It causes changes and remodeling in the walls of the vessels that include thickening, narrowing and scarring. As a result, the blood flow to the organs and tissues gets restricted leading to organ damage. The cause of primary vasculitis is not known; however, most cases are thought to be autoimmune. In the present era, it is getting difficult to treat vasculitis with conventional therapies, which includes cyclophosphamide, methotrexate, azathioprine and mycophenolate mofetil, with increasing rates of relapses. Since ever, corticosteroids and cytotoxic agents or immunosuppressants have been the mainstay for treating systemic vasculitis. However, the introduction of newer biological agents have bring about a revolution in the treatment of relapses and in cases where there is failure to induce and sustain remission.

Microvascular system of the lumbar dorsal root ganglia in rats. Part II: neurogenic control of intraganglionic blood flow

2010 ◽  
Vol 12 (2) ◽  
pp. 203-209 ◽  
Author(s):  
Shigeru Kobayashi ◽  
Erisa Sabakaki Mwaka ◽  
Hisatoshi Baba ◽  
Yasuo Kokubo ◽  
Takafumi Yayama ◽  
...  
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Dorsal Root ◽  
Vascular System ◽  
Sensory Nerves ◽  
Acid Decarboxylase ◽  
Autonomic Nerves ◽  
Complex Method ◽  
Amino Acid Decarboxylase ◽  
Calcitonin Gene

Object The dorsal root ganglion (DRG) should not be overlooked when considering the mechanism of low-back pain and sciatica, so it is important to understand the morphological features of the vascular system supplying the DRG. However, the neurogenic control of intraganglionic blood flow has received little attention in the past. The authors used an immunohistochemical technique to investigate the presence and distribution of autonomic and sensory nerves in blood vessels of the DRG. Methods Ten Wistar rats were used. To investigate the mechanism of vasomotion on the lumbar DRG, the authors used immunohistochemical methods. Sections were incubated overnight with antisera to tyrosine hydroxylase (TH), aromatic l-amino-acid decarboxylase (AADC), 5-hydroxytryptamine, substance P (SP), calcitonin gene–related peptide (CGRP), vasoactive intestinal peptide (VIP), somatostatin (SOM), neuropeptide Y (NPY), leucine-enkephalin, and cholineacetyl transferase (Ch-E). The avidin-biotin complex method was used as the immunohistochemical procedure, and the sections were observed under a light microscope. Results In the immunohistochemical study, TH-, AADC-, SP-, CGRP-, VIP-, SOM-, NPY-, and Ch-E–positive fibers were seen within the walls of blood vessels in the DRG. This study revealed the existence of a comprehensive perivascular adrenergic, cholinergic, and peptidergic innervation of intraganglionic blood vessels, with a possible role in neurogenic regulation (autoregulation) of intraganglionic circulation. Conclusions The presence of perivascular nerve plexuses around intraganglionic microvessels suggests that autonomic nerves play an important role in intraganglionic circulation.

scholarly journals Mechanical, hormonal and metabolic influences on blood vessels, blood flow and bone

2017 ◽  
Vol 235 (3) ◽  
pp. R77-R100 ◽  
Author(s):  
Rhonda D Prisby
Keyword(s):  
Bone Marrow ◽  
Blood Flow ◽  
Trabecular Bone ◽  
Blood Vessels ◽  
Vascular Endothelium ◽  
Bone Cells ◽  
Vascular System ◽  
Bone Volume ◽  
Bone Blood Flow ◽  
Trabecular Bone Volume

Bone tissue is highly vascularized due to the various roles bone blood vessels play in bone and bone marrow function. For example, the vascular system is critical for bone development, maintenance and repair and provides O2, nutrients, waste elimination, systemic hormones and precursor cells for bone remodeling. Further, bone blood vessels serve as egress and ingress routes for blood and immune cells to and from the bone marrow. It is becoming increasingly clear that the vascular and skeletal systems are intimately linked in metabolic regulation and physiological and pathological processes. This review examines how agents such as mechanical loading, parathyroid hormone, estrogen, vitamin D and calcitonin, all considered anabolic for bone, have tremendous impacts on the bone vasculature. In fact, these agents influence bone blood vessels prior to influencing bone. Further, data reveal strong associations between vasodilator capacity of bone blood vessels and trabecular bone volume, and poor associations between estrogen status and uterine mass and trabecular bone volume. Additionally, this review highlights the importance of the bone microcirculation, particularly the vascular endothelium and NO-mediated signaling, in the regulation of bone blood flow, bone interstitial fluid flow and pressure and the paracrine signaling of bone cells. Finally, the vascular endothelium as a mediator of bone health and disease is considered.

Geometrical Models of Vertebral Arteries and Numerical Simulations of the Blood Flow Through Them

2008 ◽  
Author(s):  
Krzysztof Jozwik ◽  
Damian Obidowski
Keyword(s):  
Blood Flow ◽  
Numerical Simulations ◽  
Blood Vessels ◽  
Human Body ◽  
Special Kind ◽  
3D Models ◽  
Vertebral Arteries ◽  
The Individual ◽  
Physical Phenomena ◽  
The Brain

Vertebral arteries are a system of two blood vessels through which blood is carried to the rear region of the brain. This region of the human body has to be very well supplied with blood, without any breaks or deficiencies in the blood flow. Blood is delivered to the brain through carotid arteries as well. All these arteries are connected to the circle of Willis, which has to fulfill all demands of the human brain as far as the blood flow is concerned. However, vertebral arteries due to their position and shape are a special kind of blood vessels. They originate at various distances from the aortic ostium, may branch off at different angles, have various length, inner diameter and spatial shape. Three different geometries of vertebral arteries, which most frequently occur in the human body structure, have been chosen, and for each twenty five various combinations of artery inner diameters have been used to generate 3D models of these arteries. For seventy five different models thus created, the numerical simulations have been performed. The results obtained have indicated explicitly that differences in the flow and instantaneous velocity values in vertebral arteries and in the point they join to form the basilar artery do not result from pathological changes in the artery system, but may follow from physical phenomena that occur in arteries as a consequence of the pulsating character of the flow and the unique geometry, which is related to the individual human anatomical structure.

Chōng $$ an Ancient Chinese Description of the Vascular System?

2014 ◽  
Vol 32 (3) ◽  
pp. 279-285 ◽  
Author(s):  
Vivien Shaw
Keyword(s):  
Internal Medicine ◽  
Blood Vessels ◽  
Human Body ◽  
Vascular System ◽  
Vena Cava ◽  
Vascular Anatomy ◽  
The Body ◽  
Acupuncture Points ◽  
Chinese Texts ◽  
The Ancient Chinese

The objectives of this research are, first, to establish if the extraordinary acupuncture meridian known as Chōng $$ Penetrating Vessel or Sea of Blood, is in essence a description of certain macroscopic parts of the underlying vascular system and, second, by extension, to show that it is likely that cadaveric dissection would have been used as a tool to arrive at this understanding. Generally accepted scholarly opinion holds that the ancient Chinese rarely used dissection in order to explore the anatomy of the human body, and that the meridians are therefore invisible metaphysical structures corresponding to lines drawn on the body. However, the seminal text, ‘The Yellow Emperor's Classic of Internal Medicine’, describes using palpation to examine the living and dissection to examine the dead. This implies that the original authors of these texts were observing physical structures visible to the naked eye. Dissection has therefore been used to compare the descriptions of the Chōng meridian in ‘The Yellow Emperor's Classic of Internal Medicine’ with the vascular anatomy of the human body. Fifteen acupuncture points located on various different ordinary meridians but bearing the same name, Chōng $$ were also examined to see if they bore any relationship to the vascular system. The dissections clearly show that the Chōng meridian correlates to certain main blood vessels in the body, in particular the vena cava. Similarly, most Chōng acupuncture points have a strong correspondence with blood vessels, marking terminal arteries on the hands, feet and forehead and anastomoses on the face, body and feet. These findings strongly suggest that the ancient Chinese texts relating to this meridian are likely to have been a ‘description’ of the vascular system. Furthermore, the ancient Chinese apparently had a high degree of anatomical skill in the practice of dissection and acute powers of observation.

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.

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