Author: Peter R. Kvietys
Publisher: Morgan & Claypool Publishers
ISBN: 1615041176
Category : Medical
Languages : en
Pages : 127
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Book Description
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: Peter R. Kvietys
Publisher: Morgan & Claypool Publishers
ISBN: 1615041176
Category : Medical
Languages : en
Pages : 127
Get Book
Book Description
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: Roland N. Pittman
Publisher: Biota Publishing
ISBN: 1615047212
Category : Medical
Languages : en
Pages : 117
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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: J. Gordon Betts
Publisher:
ISBN: 9781947172807
Category :
Languages : en
Pages : 0
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Book Description
Author: J.L. Rombeau
Publisher: Springer Science & Business Media
ISBN: 3642802249
Category : Medical
Languages : en
Pages : 402
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Book Description
Dysfunction of the gastrointestinal tract in critically ill patients has recently become a focus of intensive research. This book, the first one on this topic, is a comprehensive overview of what is currently known about the role of the gut in patients requiring intensive care. The definitions and pathogenesis of intestinal dysfunction are critically evaluated. Currently available and potential new ways to monitor intestinal function in the intensive care setting are presented. Emphasis has been placed on the evaluation of therapeutic strategies in the prevention and treatment of gut dysfunction. Options for monitoring and treating gut dysfunction in critically ill patients are rapidly evolving. This volume provides state-of-the-art information for both clinicians and clinical researchers.
Author: Sushil K. Sarna
Publisher: Biota Publishing
ISBN: 1615041516
Category : Medical
Languages : en
Pages : 159
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Book Description
Three distinct types of contractions perform colonic motility functions. Rhythmic phasic contractions (RPCs) cause slow net distal propulsion with extensive mixing/turning over. Infrequently occurring giant migrating contractions (GMCs) produce mass movements. Tonic contractions aid RPCs in their motor function. The spatiotemporal patterns of these contractions differ markedly. The amplitude and distance of propagation of a GMC are several-fold larger than those of an RPC. The enteric neurons and smooth muscle cells are the core regulators of all three types of contractions. The regulation of contractions by these mechanisms is modifiable by extrinsic factors: CNS, autonomic neurons, hormones, inflammatory mediators, and stress mediators. Only the GMCs produce descending inhibition, which accommodates the large bolus being propelled without increasing muscle tone. The strong compression of the colon wall generates afferent signals that are below nociceptive threshold in healthy subjects. However, these signals become nociceptive; if the amplitudes of GMCs increase, afferent nerves become hypersensitive, or descending inhibition is impaired. The GMCs also provide the force for rapid propulsion of feces and descending inhibition to relax the internal anal sphincter during defecation. The dysregulation of GMCs is a major factor in colonic motility disorders: irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and diverticular disease (DD). Frequent mass movements by GMCs cause diarrhea in diarrhea predominant IBS, IBD, and DD, while a decrease in the frequency of GMCs causes constipation. The GMCs generate the afferent signals for intermittent short-lived episodes of abdominal cramping in these disorders. Epigenetic dysregulation due to adverse events in early life is one of the major factors in generating the symptoms of IBS in adulthood.
Author: Rainer Greger
Publisher: Springer Science & Business Media
ISBN: 3642609465
Category : Medical
Languages : en
Pages : 2478
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Book Description
Comprehensive Human Physiology is a significantly important publication on physiology, presenting state-of-the-art knowledge about both the molecular mechanisms and the integrative regulation of body functions. This is the first time that such a broad range of perspectives on physiology have been combined to provide a unified overview of the field. This groundbreaking two-volume set reveals human physiology to be a highly dynamic science rooted in the ever-continuing process of learning more about life. Each chapter contains a wealth of original data, clear illustrations, and extensive references, making this a valuable and easy-to-use reference. This is the quintessential reference work in the fields of physiology and pathophysiology, essential reading for researchers, lecturers and advanced students.
Author: Christine Norton
Publisher: Oxford University Press, USA
ISBN: 0199298653
Category : Medical
Languages : en
Pages : 762
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Book Description
"This practical guide to all aspects of gastrointestinal nursing covers the treatment of a wide range of patients - from those suffering from minor and acute disorders, through chronic conditions, to those requiring major surgery and treatment for malignant disease. It summarizes the current state of knowledge in gastrointestinal nursing and provides concise, user-friendly guidelines on the management and treatment of patients with gastrointestinal disorders." "Written by practising nurses and subject experts, and incorporating their years of experience, the Oxford Handbook of Gastrointestinal Nursing is a unique and invaluable companion for practising nurses, and for all health care professionals who are involved in the care of patients with gastrointestinal disorders."--BOOK JACKET.
Author: Webb
Publisher: Oxford University Press
ISBN: 0198855435
Category : Medical
Languages : en
Pages : 1961
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Book Description
Now in paperback, the second edition of the Oxford Textbook of Critical Care is a comprehensive multi-disciplinary text covering all aspects of adult intensive care management. Uniquely this text takes a problem-orientated approach providing a key resource for daily clinical issues in the intensive care unit. The text is organized into short topics allowing readers to rapidly access authoritative information on specific clinical problems. Each topic refers to basic physiological principles and provides up-to-date treatment advice supported by references to the most vital literature. Where international differences exist in clinical practice, authors cover alternative views. Key messages summarise each topic in order to aid quick review and decision making. Edited and written by an international group of recognized experts from many disciplines, the second edition of the Oxford Textbook of Critical Careprovides an up-to-date reference that is relevant for intensive care units and emergency departments globally. This volume is the definitive text for all health care providers, including physicians, nurses, respiratory therapists, and other allied health professionals who take care of critically ill patients.
Author:
Publisher:
ISBN: 9789630526913
Category :
Languages : en
Pages : 0
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Book Description
