This book is aimed at those working on the physical aspects of heart and circulation. However, the book has a much wider scope: it also presents the physical and mathematical basis for the study of biological systems, not only as a way of thinking but also presenting basic information on all aspects of the cardiovascular system, such as fluid dynamics, elasticity, potential theory, mathematical modelling, etc. The book is of interest to graduate students and researchers in biomedical engineering, medical physics and the clinical sciences.
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.
The fields of biological and medical physics and biomedical engineering are broad, multidisciplinary and dyanmic. They lie at the crossroads of frontier - search in physics, biology, chemistry, and medicine. The Biological & Me- cal Physics/Biomedical Engineering Series is intended to be comprehensive, covering a broad range of topics important to the study of the physical, che- cal and biological sciences. Its goal is to provide scientists and engineers with textbooks, monographs, and reference works to address the growing need for information. Books in the series emphasize established and emergent areas of science - cluding molecular, membrane, and mathematical biophysics; photosynthetic - ergy harvesting and conversion; information processing; physical principles of genetics; sensory communications; automata networks, neural networks, and cellular automata. Equally important will be coverage of applied aspects of b- logical and medical physics and biomedical engineering such as molecular el- tronic components and devices, biosensors, medicine, imaging, physical prin- ples of renewable energy production, advanced prostheses, and environmental control and engineering. Elias Greenbaum Oak Ridge, TN M. Zamir Department of Applied Mathematics University of Western Ontario London, Ontario, N6A 5B7 CANADA [email protected] Library of Congress Cataloging-in-Publication Data Zamir, M. (Mair) The physics of coronary blood flow / M. Zamir. p. cm. — (Biological and medical physics, biomedical engineering) Includes bibliographical references and index. 1. Coronary circulation. 2. Hemodynamics. 3. Blood flow. I. Title. II. Series. QP108.Z36 2005 612.1?7—dc22 2005042502 ISBN-10: 0-387-25297-5 e-ISBN: 0-387-26019-6 Printed on acid-free paper.
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.
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.
Circulatory System Dynamics reviews cardiovascular dynamics from the analytical viewpoint and indicates ways in which the accumulated knowledge can be expanded and applied to further enhance understanding of the normal mammalian circulation, to ascertain the nature of difficulties associated with disease, and to test the effect of treatment. Comprised of 10 chapters, this volume begins with an overview of the circulatory system, including its anatomy and the trigger for myocardial (heart muscle) contraction. The discussion then turns to measurement of blood pressure using invasive and non-invasive techniques; blood flow measurement, with emphasis on cardiac output and measurement in the microcirculation; the system and pulmonary arterial trees; and pulsatile pressure and flow in pulmonary veins. Subsequent chapters explore microcirculation and the anatomy of the microvasculature; the heart and coronary circulation, paying particular attention to the Frank-Starling mechanism and indices of myocardial "contractility"; and control of blood pressure, peripheral resistance, and cerebral flow. The last two chapters deal with circulatory assistance and the closed cardiovascular system. This book will be of interest to students, practitioners, and researchers in fields ranging from physiology and biology to biochemistry and biophysics.
Subjects in the monograph “Biophysics of the Failing Heart” include state of the art chapters considering major biophysical mechanisms for why hearts responding to acquired or inherited stressors enter into maladaptive processes eventually leading to an inability of the heart to respond efficiently to hemodynamic loads especially during exercise. The chapters describe biophysical techniques that have been applied to determine the triggers for the heart failure process as well as the mechanisms for sustaining the disorders. These techniques include measurements of active and passive mechanical properties and hemodynamics at levels of organization ranging from molecules to hearts beating in situ. Biophysical concepts and approaches are also applied to determination of signaling and signal transduction, energetics, ionic currents, transport processes, electro-chemical and chemo-mechanical coupling. By its emphasis on biophysical aspects of a prevalent clinical condition, the monograph is unique in its perspective and focus. The breadth of information in the chapters all in one place will be of value to clinicians and researchers at all levels. Modern research approaches and clinical understanding of heart failure demands integration of multiple aspects of the disorders. In most cases, combinations of clinician scientists and researchers author the chapters. A main benefit of the book is couched in its didactic approach together with its emphasis on how biophysical concepts and techniques aid in diagnosis and development of new therapies.
