Hypoxia

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.

Periods of environmental hypoxia (Low Oxygen Availability) are extremely common in aquatic systems due to both natural causes such as diurnal oscillations in algal respiration, seasonal flooding, stratification, under ice cover in lakes, and isolation of densely vegetated water bodies, as well as more recent anthropogenic causes (e.g. eutrophication). In view of this, it is perhaps not surprising that among all vertebrates, fish boast the largest number of hypoxia tolerant species; hypoxia has clearly played an important role in shaping the evolution of many unique adaptive strategies. These unique adaptive strategies either allow fish to maintain function at low oxygen levels, thus extending hypoxia tolerance limits, or permit them to defend against the metabolic consequences of oxygen levels that fall below a threshold where metabolic functions cannot be maintained. The aim of this volume is two-fold. First, this book will review and synthesize the adaptive behavioural, morphological, physiological, biochemical, and molecular strategies used by fish to survive hypoxia exposure and place them within an environmental and ecological context. Second, through the development of a synthesis chapter this book will serve as the cornerstone for directing future research into the effects of hypoxia exposures on fish physiology and biochemistry. The only single volume available to provide an in-depth discussion of the adaptations and responses of fish to environmental hypoxia Reviews and synthesizes the adaptive behavioural, morphological, physiological, biochemical, and molecular strategies used by fish to survive hypoxia exposure Includes discussion of the evolutionary and ecological consequences of hypoxia exposure in fish

This book contains a total of 21 chapters, each of which was written by experts in the corresponding field. The objective of this book is to provide a comprehensive and updated overview of cellular and molecular mechanisms underlying hypoxia's impacts on human health, as well as current advances and future directions in the detection, recognition, and management of hypoxia-related disorders. This collection of articles provides a clear update in the area of hypoxia research for biomedical researchers, medical students, nurse practitioners, and practicing clinicians in the fields of high altitude biology, cardiovascular biology and medicine, tumor oncology, obstetrics, pediatrics, and orthodontics and for others who may be interested in hypoxia.

We have all been hypoxic. Fetal tolerance for intrauterine hypoxia arises from evolutionarily conserved physiological mechanisms, the antecedents of which can be learned from diving mammals or species at high altitudes. Understanding fetal hypoxia leads to understanding the huge physiological shifts of neonatal transition and the dangers of perinatal hypoxia. This comprehensive volume of topical review articles by expert authors addresses the origins of hypoxia tolerance, the impact of oxygen on circulatory transition at birth, and the biochemistry of hypoxia in the pulmonary circuit, as well as the classification, diagnosis, and clinical management of hypoxic respiratory failure and persistent pulmonary hypertension in the term neonate. The goal of Hypoxic Respiratory Failure in the Newborn is to connect our understanding of hypoxia from animals in extreme environments, with how the human fetus handles its hypoxic environment; and why the human newborn suddenly cannot. The book will educate health care professionals on how to care for newborns with hypoxic respiratory failure, including the use of up-to-date diagnostic tools and therapies. It also highlights areas of controversy and ongoing research in hypoxic respiratory failure and pulmonary hypertension of the newborn, including challenging case studies. Key Features Explores evolutionary context and comparative physiology of hypoxia tolerance in the fetus and neonate, from basic research to clinical scenarios Provides guidance to trainees, physicians, and allied health professionals engaged in NICU care; pediatricians, cardiologists, pulmonologists, anesthesiologists, neonatologists, and physiologists to effectively manage infants in hypoxic respiratory failure Includes case scenarios emphasizing current diagnostic and therapeutic controversies and algorithmic approaches to decipher difficult clinical cases

Intermittent hypoxia can cause significant structural and functional impact on the systemic, organic, cellular and molecular processes of human physiology and pathophysiology. This book focuses on the most updated scientific understanding of the adaptive (beneficial) and maladaptive (detrimental) responses to intermittent hypoxia and their potential pathogenetic or prophylactic roles in the development and progression of major human diseases. This is a comprehensive monograph for clinicians, research scientists, academic faculty, postgraduate and medical students, and allied health professionals who are interested in enhancing their up-to-date knowledge of intermittent hypoxia research and its translational applications in preventing and treating major human diseases.

The latest in a series of books from the International Hypoxia Symposia, this volume spans reviews on key topics in hypoxia, and abstracts from poster and oral presentations. The biannual International Hypoxia Symposia are dedicated to hosting the best basic scientific and clinical minds to focus on the integrative and translational biology of hypoxia. Long before ‘translational medicine’ was a catchphrase, the founders of the International Hypoxia Symposia brought together basic scientists, clinicians and physiologists to live, eat, ski, innovate and collaborate in the Canadian Rockies. This collection of reviews and abstracts is divided into six sections, each covering new and important work relevant to a broad range of researchers interested in how humans adjust to hypoxia, whether on the top of Mt. Everest or in the pulmonary or cardiology clinic at low altitude. The sections include: Epigenetic Variations in Hypoxia High Altitude Adaptation Hypoxia and Sleep Hypoxia and the Brain Molecular Oxygen Sensing Physiological Responses to Hypoxia

Brain Hypoxia and Ischemia explores the various aspects of cell death and survival that are crucial for understanding the basic mechanisms underlying brain hypoxia and ischemia. Chapters focus on a panorama of issues including the role of ion channels/transporters, mitochondria and apoptotic mechanisms, the roles of glutamate/NMDA, mechanisms in penumbral cells and the importance of intermittent hypoxia and gene regulation under these stressful conditions. The volume explores findings from both mammalian and invertebrate model systems and their applicability to human systems and diseases. Careful consideration is also given to differences in hypoxia and ischemia across development. This volume aims to increase the understanding of these mechanisms and to stimulate research on better diagnosis and treatment of diseases that afflict the brain and potentially other organs when O2 levels are dysregulated. Brain Hypoxia and Ischemia is designed for neuroscientists, clinicians and medical/graduate students for use in both basic research and clinical practice.

In a concise manner, this book presents common surgical problems encountered by medical students and residents. The book provides easy access for residents before teaching rounds, lectures, etc. The algorithm approach lends itself to rapid learning, making the book a must for every surgical resident.