Human Cardiovascular Control

This new analysis of reflex and hormonal control of the human cardiovascular system developed from questions raised in Human Circulation: During Physical Stress (Rowell, 1986) and from recent findings. The goal is to help students, physiologists and clinicians understand the control of pressure, vascular volume, and blood flow by examining the cardiovascular system during orthostasis and exercise, two stresses that most affect these variables. A discussion of the passive physical properties of the vascular system provides a basis for explaining how vascular control is modified by mechanical, neural, and humoral factors. Interactive effects of the vasculature on cardiac performance are emphasized; they reveal the importance of autonomic control, supplemented by muscle pumping, in maintaining adequate ventricular filling pressure. The author's detailed analysis of how total oxygen consumption is restricted focuses on limitations in cardiac pumping ability, oxygen diffusion from lungs to blood and from blood to active muscle, oxidative metabolism and neural control of organ blood flow. An unsolved mystery is the nature of the signals that govern the cardiovascular responses to exercise. This is discussed in a new and critical synthesis of ideas and evidence concerning the "error signals" that are sensed and then corrected by activation of the autonomic nervous system during exercise.

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.

Here is the first single-volume work to analyze in a comprehensive manner the mechanisms by which the human cardiovascular system adjusts to physical stresses such as exercise, heat, upright posture, and hypoxia. Emphasizing the regulation of regional blood flow and blood volume, the work delineates the unique character of the human cardiovascular system and the regulatory problems it faces. It represents a timely response to the growing interest in cardiovascular health, exercise, and physical conditioning. In describing the basic mechanisms of vasomotor control, the author focuses on the interaction between the arterial and venous systems. He indicates how control of regional circulations interacts with control of venous volume and cardiac performance, showing how vasomotor and venomotor regulation serves the entire organism. This treatment redresses an imbalance in contemporary teaching of cardiovascular physiology which has focused more on the heart than on the vasculature. The book utilizes graphics imaginatively throughout to clarify concepts in a fresh and effective way. Features: * Analytical, quantitative, and problem oriented * Uniquely comprehensive; coverage extends from small blood vessel functioning to the entire system * Imaginatively illustrated, with exceptionally clear graphics that explain basic principles and controversial ideas * Original, new ideas on how peripheral circulation influences heart performance * Probes the upper limits of human cardiovascular function, their causes and how they change

Addresses the mathematical and numerical modelling of the human cardiovascular system, from patient data to clinical applications.

Advanced Cardiovascular Exercise Physiology details the effect of acute and chronic exercise training on each component of the cardiovascular system and how those components adapt to and benefit from a systematic program of exercise training.

An Introduction to Cardiovascular Physiology is designed primarily for students of medicine and physiology. This introductory text is mostly didactic in teaching style and it attempts to show that knowledge of the circulatory system is derived from experimental observations. This book is organized into 15 chapters. The chapters provide a fuller account of microvascular physiology to reflect the explosion of microvascular research and include a discussion of the fundamental function of the cardiovascular system involving the transfer of nutrients from plasma to the tissue. They also cover major advances in cardiovascular physiology including biochemical events underlying Starling's law of the heart, nonadrenergic, non-cholinergic neurotransmission, the discovery of new vasoactive substances produced by endothelium and the novel concepts on the organization of the central nervous control of the circulation. This book is intended to medicine and physiology students.

Caffeine in Food and Dietary Supplements is the summary of a workshop convened by the Institute of Medicine in August 2013 to review the available science on safe levels of caffeine consumption in foods, beverages, and dietary supplements and to identify data gaps. Scientists with expertise in food safety, nutrition, pharmacology, psychology, toxicology, and related disciplines; medical professionals with pediatric and adult patient experience in cardiology, neurology, and psychiatry; public health professionals; food industry representatives; regulatory experts; and consumer advocates discussed the safety of caffeine in food and dietary supplements, including, but not limited to, caffeinated beverage products, and identified data gaps. Caffeine, a central nervous stimulant, is arguably the most frequently ingested pharmacologically active substance in the world. Occurring naturally in more than 60 plants, including coffee beans, tea leaves, cola nuts and cocoa pods, caffeine has been part of innumerable cultures for centuries. But the caffeine-in-food landscape is changing. There are an array of new caffeine-containing energy products, from waffles to sunflower seeds, jelly beans to syrup, even bottled water, entering the marketplace. Years of scientific research have shown that moderate consumption by healthy adults of products containing naturally-occurring caffeine is not associated with adverse health effects. The changing caffeine landscape raises concerns about safety and whether any of these new products might be targeting populations not normally associated with caffeine consumption, namely children and adolescents, and whether caffeine poses a greater health risk to those populations than it does for healthy adults. This report delineates vulnerable populations who may be at risk from caffeine exposure; describes caffeine exposure and risk of cardiovascular and other health effects on vulnerable populations, including additive effects with other ingredients and effects related to pre-existing conditions; explores safe caffeine exposure levels for general and vulnerable populations; and identifies data gaps on caffeine stimulant effects.