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Author: R. John Solaro Publisher: Biota Publishing ISBN: 1615041753 Category : Medical Languages : en Pages : 46
Book Description
Contractility describes the relative ability of the heart to eject a stroke volume (SV) at a given prevailing afterload (arterial pressure) and preload (end-diastolic volume; EDV). Various measures of contractility are related to the fraction as the SV/EDV or the ejection fraction, and the dynamics of ejection as determined from maximum pressure rise in the ventricles or arteries or from aortic flow velocities determined by echocardiography. At the cellular level, the ultimate determinant of contractility is the relative tension generation and shortening capability of the molecular motors (myosin cross-bridges) of the sarcomeres as determined by the rates and extent of Ca activation, the turnover kinetics of the cross-bridges, and the relative Ca responsiveness of the sarcomeres. Engagement of the regulatory signaling cascades controlling contractility occurs with occupancy and signal transduction by receptors for neurohumors of the autonomic nervous system as well as growth and stress signaling pathways. Contractility is also determined by the prevailing conditions of pH, temperature, and redox state. Short-term control of contractility is fully expressed during exercise. In long-term responses to stresses on the heart, contractility is modified by cellular remodeling and altered signaling that may compensate for a time but which ultimately may fail, leading to disorders.
Author: R. John Solaro Publisher: Biota Publishing ISBN: 1615041753 Category : Medical Languages : en Pages : 46
Book Description
Contractility describes the relative ability of the heart to eject a stroke volume (SV) at a given prevailing afterload (arterial pressure) and preload (end-diastolic volume; EDV). Various measures of contractility are related to the fraction as the SV/EDV or the ejection fraction, and the dynamics of ejection as determined from maximum pressure rise in the ventricles or arteries or from aortic flow velocities determined by echocardiography. At the cellular level, the ultimate determinant of contractility is the relative tension generation and shortening capability of the molecular motors (myosin cross-bridges) of the sarcomeres as determined by the rates and extent of Ca activation, the turnover kinetics of the cross-bridges, and the relative Ca responsiveness of the sarcomeres. Engagement of the regulatory signaling cascades controlling contractility occurs with occupancy and signal transduction by receptors for neurohumors of the autonomic nervous system as well as growth and stress signaling pathways. Contractility is also determined by the prevailing conditions of pH, temperature, and redox state. Short-term control of contractility is fully expressed during exercise. In long-term responses to stresses on the heart, contractility is modified by cellular remodeling and altered signaling that may compensate for a time but which ultimately may fail, leading to disorders.
Author: David Jordan Publisher: Ashgate Publishing ISBN: 9781855780248 Category : Medical Languages : en Pages : 159
Book Description
The Studies in Physiology series provides a concise introduction to developments in complex areas of physiology for a wide audience. Published on behalf of the Physiology Society, Cardiovascular Regulation provides an up-to-date account of our current understanding of the control of the cardiovascular system that is not covered by existing textbooks. Both students and lecturers of cardiovascular and exercise physiology, medicine, dentistry and biomedical sciences will find this book informative and easy to read. Each chapter has numerous summary boxes. 'Essential reading' suggestions provide additional reading for undergraduates and the suggestions for 'Further reading' cover the subject to postgraduate level.
Author: Roland N. Pittman Publisher: Biota Publishing ISBN: 1615047212 Category : Medical Languages : en Pages : 117
Book Description
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.
Author: David Young Publisher: Biota Publishing ISBN: 1615040226 Category : Medical Languages : en Pages : 110
Book Description
Although cardiac output is measured as the flow of blood from the left ventricle into the aorta, the system that controls cardiac output includes many other components besides the heart itself. The heart’s rate of output cannot exceed the rate of venous return to it, and therefore, the factors governing venous return are primarily responsible for control of output from the heart. Venous return is affected by its pressure gradient and resistance to flow throughout the vascular system. The pressure gradient for venous return is a function of several factors including the blood volume flowing through the system, the unstressed vascular volume of the circulatory system, its capacitance, mean systemic pressure, and right atrial pressure. Resistance to venous return is the sum of total vascular resistance from the aortic valve to the right atrium. The sympathetic nervous system and vasoactive circulating hormones affect short-term resistance, whereas local tissue blood flow autoregulatory mechanisms are the dominant determinants of long-term resistance to venous return. The strength of contraction of the heart responds to changes in atrial pressure driven by changes in venous return, with small changes in atrial pressure eliciting large changes in strength of contraction, as described by the Frank–Starling mechanism. In addition, the autonomic nervous system input to the heart alters myocardial pumping ability in response to cardiovascular challenges. The function of the cardiovascular system is strongly affected by the operation of the renal sodium excretion–body fluid volume–arterial pressure negative feedback system that maintains arterial blood pressure at a controlled value over long periods. The intent of this volume is to integrate the basic knowledge of these cardiovascular system components into an understanding of cardiac output regulation. Table of Contents: Introduction / Venous Return / Cardiac Function / Integrated Analysis of Cardiac Output Control / Analysis of Cardiac Output Regulation by Computer Simulation / Analysis of Cardiac Output Control in Response to Challenges / Conclusion / References / Author Biography
Author: Michitoshi Inoue Publisher: Springer Science & Business Media ISBN: 4431683674 Category : Medical Languages : en Pages : 330
Book Description
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: Hiroshi Abe Publisher: VSP ISBN: 9789067640350 Category : Medical Languages : en Pages : 346
Book Description
This book gives a consensus of views and research trends in the regulation of cardiac function and metabolism. Emphasis is given to the elucidation of fundamental concepts and principles of clinically relevant issues. The aim is that the clinician should be able to approach a particular aspect of any given problem logically, thereby gaining insights into the fundamental pathophysiological mechanism underlying diseases states. Regulation of Cardiac Function is organized within six principle areas from the molecular and cellular aspects to more clinically applied problems of heart disease. This book gives pertinent guidelines and summarizes knowledge on basic research relevant to cardiac function and metabolism in health and disease.
Author: S. Sideman Publisher: Springer Science & Business Media ISBN: 9400949928 Category : Medical Languages : en Pages : 448
Book Description
The ultrasound velocity tomography allows measurement of cardiac geometries for various phases in the cardiac cycle. The present tomograph makes reconstruc tions at intervals of 20 ms. Because of a lack of clear (intramural) landmarks (except the roots of the papillairy muscle), it is difficult to pinpoint spatial trajectories of particular points in the heart. Therefore, a second method was developed of injecting radiopaque markers in the heart and following their motion patterns during the cardiac cycle with help of a biplane X-ray equipment. The data obtained with both methods can be implemented in our finite element model of the heart to compute intramural stresses and strains. The results obtained sofar with the extended Darcy equation to account for the interaction of blood rheology and tissue mechanics look promising. Further testing with more sophisticated subjects than mentioned in Figure 9 is required before it will be implemented in our finite element model of the heart. We conclude that analysis of regional cardiac function, including regional myocardial blood flow, requires still a major research effort but the results obtained sofar justify, to our opinion, a continuation in this direction. Acknowledgement The authors acknowledge Dr. C. Borst and coworkers for doing the animal experiments and prof. Van Campen and dr. Grootenboer for their participation is some aspects of this work.
Author: R. John Solaro Publisher: Morgan & Claypool Publishers ISBN: 1615041745 Category : Medical Languages : en Pages : 47
Book Description
Contractility describes the relative ability of the heart to eject a stroke volume (SV) at a given prevailing afterload (arterial pressure) and preload (end-diastolic volume; EDV). Various measures of contractility are related to the fraction as the SV/EDV or the ejection fraction, and the dynamics of ejection as determined from maximum pressure rise in the ventricles or arteries or from aortic flow velocities determined by echocardiography. At the cellular level, the ultimate determinant of contractility is the relative tension generation and shortening capability of the molecular motors (myosin cross-bridges) of the sarcomeres as determined by the rates and extent of Ca activation, the turnover kinetics of the cross-bridges, and the relative Ca responsiveness of the sarcomeres. Engagement of the regulatory signaling cascades controlling contractility occurs with occupancy and signal transduction by receptors for neurohumors of the autonomic nervous system as well as growth and stress signaling pathways. Contractility is also determined by the prevailing conditions of pH, temperature, and redox state. Short-term control of contractility is fully expressed during exercise. In long-term responses to stresses on the heart, contractility is modified by cellular remodeling and altered signaling that may compensate for a time but which ultimately may fail, leading to disorders. Table of Contents: Introduction: Contractility and the Integrative Biology of the Myocardium / Control of Contractility Is at the Cellular Level of Organization / Left Ventricular Diastolic and Systolic Pressure, Ejection, and Relaxation Reflect Sarcomeric Mechanical Properties / Integration of Sarcomere Mechanics with Cardiac Function Clarifies the Meaning of Preload, Afterload, and Contractility / Pressure Volume Loops Provide a Quantification of Contractility / Phosphorylations of Regulatory Proteins in Excitation Contraction Coupling Modify Contractility by Controlling Cellular Ca + Fluxes, the Response of the Myofilaments to Ca +, and the Kinetics of the Cross-Bridge Cycle / Contractility May Be Altered by a Variety of Mechanisms Not Involving a Prominent Role for the Autonomic Nervous System / Cardiac Function Curves Provide a Compact Graphical Representation of Regulation of CO and SV / Heart Failure as a Failure of Contractility / References
Author: A. Kurt Gamperl Publisher: Academic Press ISBN: 0128041668 Category : Science Languages : en Pages : 480
Book Description
The Cardiovascular System: Design, Control and Function, Volume 36A, a two- volume set, not only provides comprehensive coverage of the current knowledge in this very active and growing field of research, but also highlights the diversity in cardiovascular morphology and function and the anatomical and physiological plasticity shown by fish taxa that are faced with various abiotic and biotic challenges. Updated topics in this important work include chapters on Heart Morphology and Anatomy, Cardiomyocyte Morphology and Physiology, Electrical Excitability of the Fish Heart, Cardiac Energy Metabolism, Heart Physiology and Function, Hormonal and Intrinsic Biochemical Control of Cardiac Function, and Vascular Anatomy and Morphology. In addition, chapters integrate molecular and cellular data with the growing body of knowledge on heart and in vivo cardiovascular function, and as a result, provide insights into some of the most important questions that still need to be answered. Presents a comprehensive overview of cardiovascular structure and function in fish Covers topics in a way that is ideal for researchers in fish physiology and for audiences within the fields of comparative morphology, histology, aquaculture and ecophysiology Provide insights into some of the most important questions that still need to be answered