The Pathophysiology Of The Microcirculation
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| Author | : D. Neil Granger |
| Publisher | : Morgan & Claypool Publishers |
| Total Pages | : 99 |
| Release | : 2010 |
| Genre | : Medical |
| ISBN | : 1615041656 |
The microcirculation is highly responsive to, and a vital participant in, the inflammatory response. All segments of the microvasculature (arterioles, capillaries, and venules) exhibit characteristic phenotypic changes during inflammation that appear to be directed toward enhancing the delivery of inflammatory cells to the injured/infected tissue, isolating the region from healthy tissue and the systemic circulation, and setting the stage for tissue repair and regeneration. The best characterized responses of the microcirculation to inflammation include impaired vasomotor function, reduced capillary perfusion, adhesion of leukocytes and platelets, activation of the coagulation cascade, and enhanced thrombosis, increased vascular permeability, and an increase in the rate of proliferation of blood and lymphatic vessels. A variety of cells that normally circulate in blood (leukocytes, platelets) or reside within the vessel wall (endothelial cells, pericytes) or in the perivascular space (mast cells, macrophages) are activated in response to inflammation. The activation products and chemical mediators released from these cells act through different well-characterized signaling pathways to induce the phenotypic changes in microvessel function that accompany inflammation. Drugs that target a specific microvascular response to inflammation, such as leukocyte-endothelial cell adhesion or angiogenesis, have shown promise in both the preclinical and clinical studies of inflammatory disease. Future research efforts in this area will likely identify new avenues for therapeutic intervention in inflammation. Table of Contents: Introduction / Historical Perspectives / Anatomical Considerations / Impaired Vasomotor Responses / Capillary Perfusion / Angiogenesis / Leukocyte-Endothelial Cell Adhesion / Platelet-Vessel Wall Interactions / Coagulation and Thrombosis / Endothelial Barrier Dysfunction / Epilogue / References
| Author | : Peter R. Kvietys |
| Publisher | : Morgan & Claypool Publishers |
| Total Pages | : 127 |
| Release | : 2010 |
| Genre | : Medical |
| ISBN | : 1615041176 |
The microcirculation of the gastrointestinal tract is under the control of both myogenic and metabolic regulatory systems. The myogenic mechanism contributes to basal vascular tone and the regulation of transmural pressure, while the metabolic mechanism is responsible for maintaining an appropriate balance between O2 demand and O2 delivery. In the postprandial state, hydrolytic products of food digestion elicit a hyperemia, which serves to meet the increased O2 demand of nutrient assimilation. Metabolically linked factors (e.g., tissue pO2, adenosine) are primarily responsible for this functional hyperemia. The fenestrated capillaries of the gastrointestinal mucosa are relatively permeable to small hydrolytic products of food digestion (e.g., glucose), yet restrict the transcapillary movement of larger molecules (e.g., albumin). This allows for the absorption of hydrolytic products of food digestion without compromising the oncotic pressure gradient governing transcapillary fluid movement and edema formation. The gastrointestinal microcirculation is also an important component of the mucosal defense system whose function is to prevent (and rapidly repair) inadvertent epithelial injury by potentially noxious constituents of chyme. Two pathological conditions in which the gastrointestinal circulation plays an important role are ischemia/reperfusion and chronic portal hypertension. Ischemia/reperfusion results in mucosal edema and disruption of the epithelium due, in part, to an inflammatory response (e.g., increase in capillary permeability to macromolecules and neutrophil infiltration). Chronic portal hypertension results in an increase in gastrointestinal blood flow due to an imbalance in vasodilator and vasoconstrictor influences on the microcirculation. Table of Contents: Introduction / Anatomy / Regulation of Vascular Tone and Oxygenation / Extrinsic Vasoregulation: Neural and Humoral / Postprandial Hyperemia / Transcapillary Solute Exchange / Transcapillary Fluid Exchange / Interaction of Capillary and Interstitial Forces / Gastrointestinal Circulation and Mucosal Defense / Gastrointestinal Circulation and Mucosal Pathology I: Ischemia/Reperfusion / Gastrointestinal Circulation and Mucosal Pathology II: Chronic Portal Hypertension / Summary and Conclusions / References / Author Biography
| Author | : Ronald F. Tuma |
| Publisher | : Academic Press |
| Total Pages | : 999 |
| Release | : 2011-04-28 |
| Genre | : Science |
| ISBN | : 0080569935 |
This reference is a volume in the Handbook of Physiology, co-published with The American Physiological Society. Growth in knowledge about the microcirculation has been explosive with the field becoming fragmented into numerous subdisciplines and subspecialties. This volume pulls all of the critical information into one volume. - Meticulously edited and reviewed. Benefit: Provides investigators a unique tool to explore the significance of their findings in the context of other aspects of the microcirculation. In this way, the updated edition has a direct role in helping to develop new pathways of research and scholarship - Highlights the explosive growth in knowledge about the microcirculation including the biology of nitric oxide synthase (NOS), endothelial cell signaling, angiogenesis, cell adhesion molecules, lymphocyte trafficking, ion channels and receptors, and propagated vasomotor responses. Benefit: Microcirculatory biology has become fragmented into numerous sub-disciplines and subspecialties, and these reference reintegrates the information in one volume
| Author | : Michitoshi Inoue |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 330 |
| Release | : 2013-11-09 |
| Genre | : Medical |
| ISBN | : 4431683674 |
Research centering on blood flow in the heart continues to hold an important position, especially since a better understanding of the subject may help reduce the incidence of coronary arterial disease and heart attacks. This book summarizes recent advances in the field; it is the product of fruitful cooperation among international scientists who met in Japan in May, 1990 to discuss the regulation of coronary blood flow.
| Author | : Marilyn J. Cipolla |
| Publisher | : Biota Publishing |
| Total Pages | : 82 |
| Release | : 2016-07-28 |
| Genre | : Medical |
| ISBN | : 1615047239 |
This e-book will review special features of the cerebral circulation and how they contribute to the physiology of the brain. It describes structural and functional properties of the cerebral circulation that are unique to the brain, an organ with high metabolic demands and the need for tight water and ion homeostasis. Autoregulation is pronounced in the brain, with myogenic, metabolic and neurogenic mechanisms contributing to maintain relatively constant blood flow during both increases and decreases in pressure. In addition, unlike peripheral organs where the majority of vascular resistance resides in small arteries and arterioles, large extracranial and intracranial arteries contribute significantly to vascular resistance in the brain. The prominent role of large arteries in cerebrovascular resistance helps maintain blood flow and protect downstream vessels during changes in perfusion pressure. The cerebral endothelium is also unique in that its barrier properties are in some way more like epithelium than endothelium in the periphery. The cerebral endothelium, known as the blood-brain barrier, has specialized tight junctions that do not allow ions to pass freely and has very low hydraulic conductivity and transcellular transport. This special configuration modifies Starling's forces in the brain microcirculation such that ions retained in the vascular lumen oppose water movement due to hydrostatic pressure. Tight water regulation is necessary in the brain because it has limited capacity for expansion within the skull. Increased intracranial pressure due to vasogenic edema can cause severe neurologic complications and death.
| Author | : Arisztid G. B. Kovách |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 1981 |
| Genre | : |
| ISBN | : 9789630526913 |
| Author | : Ronald J. Korthuis |
| Publisher | : Morgan & Claypool Publishers |
| Total Pages | : 147 |
| Release | : 2011 |
| Genre | : Medical |
| ISBN | : 1615041834 |
The aim of this treatise is to summarize the current understanding of the mechanisms for blood flow control to skeletal muscle under resting conditions, how perfusion is elevated (exercise hyperemia) to meet the increased demand for oxygen and other substrates during exercise, mechanisms underlying the beneficial effects of regular physical activity on cardiovascular health, the regulation of transcapillary fluid filtration and protein flux across the microvascular exchange vessels, and the role of changes in the skeletal muscle circulation in pathologic states. Skeletal muscle is unique among organs in that its blood flow can change over a remarkably large range. Compared to blood flow at rest, muscle blood flow can increase by more than 20-fold on average during intense exercise, while perfusion of certain individual white muscles or portions of those muscles can increase by as much as 80-fold. This is compared to maximal increases of 4- to 6-fold in the coronary circulation during exercise. These increases in muscle perfusion are required to meet the enormous demands for oxygen and nutrients by the active muscles. Because of its large mass and the fact that skeletal muscles receive 25% of the cardiac output at rest, sympathetically mediated vasoconstriction in vessels supplying this tissue allows central hemodynamic variables (e.g., blood pressure) to be spared during stresses such as hypovolemic shock. Sympathetic vasoconstriction in skeletal muscle in such pathologic conditions also effectively shunts blood flow away from muscles to tissues that are more sensitive to reductions in their blood supply that might otherwise occur. Again, because of its large mass and percentage of cardiac output directed to skeletal muscle, alterations in blood vessel structure and function with chronic disease (e.g., hypertension) contribute significantly to the pathology of such disorders. Alterations in skeletal muscle vascular resistance and/or in the exchange properties of this vascular bed also modify transcapillary fluid filtration and solute movement across the microvascular barrier to influence muscle function and contribute to disease pathology. Finally, it is clear that exercise training induces an adaptive transformation to a protected phenotype in the vasculature supplying skeletal muscle and other tissues to promote overall cardiovascular health. Table of Contents: Introduction / Anatomy of Skeletal Muscle and Its Vascular Supply / Regulation of Vascular Tone in Skeletal Muscle / Exercise Hyperemia and Regulation of Tissue Oxygenation During Muscular Activity / Microvascular Fluid and Solute Exchange in Skeletal Muscle / Skeletal Muscle Circulation in Aging and Disease States: Protective Effects of Exercise / References
| Author | : Filippo Crea |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 263 |
| Release | : 2013-08-15 |
| Genre | : Medical |
| ISBN | : 8847053676 |
In the past two decades a number of studies have shown that abnormalities in the function and structure of coronary microcirculation can be detected in several cardiovascular diseases. On the basis of the clinical setting in which it occurs, coronary microvascular dysfunction (CMD) can be classified into four types: CMD in the absence of any other cardiac disease; CMD in myocardial diseases; CMD in obstructive epicardial coronary artery disease; and iatrogenic CMD. In some instances CMD represents an epiphenomenon, whereas in others it represents an important marker of risk or may contribute to the pathogenesis of myocardial ischemia, thus becoming a possible therapeutic target. This book provides an update on coronary physiology and a systematic assessment of microvascular abnormalities in cardiovascular diseases, in the hope that it will assist clinicians in prevention, detection and management of CMD in their everyday activity.
| Author | : Cyril Mauffrey |
| Publisher | : Springer Nature |
| Total Pages | : 187 |
| Release | : 2019-09-02 |
| Genre | : Medical |
| ISBN | : 3030223310 |
Compartment syndrome is a complex physiologic process with significant potential harm, and though an important clinical problem, the basic science and research surrounding this entity remains poorly understood. This unique open access book fills the gap in the knowledge of compartment syndrome, re-evaluating the current state of the art on this condition. The current clinical diagnostic criteria are presented, as well as the multiple dilemmas facing the surgeon. Pathophysiology, ischemic thresholds and pressure management techniques and limitations are discussed in detail. The main surgical management strategy, fasciotomy, is then described for both the upper and lower extremities, along with wound care. Compartment syndrome due to patient positioning, in children and polytrauma patients, and unusual presentations are likewise covered. Novel diagnosis and prevention strategies, as well as common misconceptions and legal ramifications stemming from compartment syndrome, round out the presentation. Unique and timely, Compartment Syndrome: A Guide to Diagnosis and Management will be indispensable for orthopedic and trauma surgeons confronted with this common yet challenging medical condition.
| Author | : Roland N. Pittman |
| Publisher | : Biota Publishing |
| Total Pages | : 117 |
| Release | : 2016-08-18 |
| Genre | : Medical |
| ISBN | : 1615047212 |
This presentation describes various aspects of the regulation of tissue oxygenation, including the roles of the circulatory system, respiratory system, and blood, the carrier of oxygen within these components of the cardiorespiratory system. The respiratory system takes oxygen from the atmosphere and transports it by diffusion from the air in the alveoli to the blood flowing through the pulmonary capillaries. The cardiovascular system then moves the oxygenated blood from the heart to the microcirculation of the various organs by convection, where oxygen is released from hemoglobin in the red blood cells and moves to the parenchymal cells of each tissue by diffusion. Oxygen that has diffused into cells is then utilized in the mitochondria to produce adenosine triphosphate (ATP), the energy currency of all cells. The mitochondria are able to produce ATP until the oxygen tension or PO2 on the cell surface falls to a critical level of about 4–5 mm Hg. Thus, in order to meet the energetic needs of cells, it is important to maintain a continuous supply of oxygen to the mitochondria at or above the critical PO2 . In order to accomplish this desired outcome, the cardiorespiratory system, including the blood, must be capable of regulation to ensure survival of all tissues under a wide range of circumstances. The purpose of this presentation is to provide basic information about the operation and regulation of the cardiovascular and respiratory systems, as well as the properties of the blood and parenchymal cells, so that a fundamental understanding of the regulation of tissue oxygenation is achieved.
