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The Journal of Physiology Mar 1949
Topics: Blood Circulation; Humans
PubMed: 18128152
DOI: No ID Found -
Journal of the American Heart... Aug 2017
Review
Topics: Animals; Blood Circulation; Blood Volume; Coronary Circulation; Fluid Shifts; Heart Failure; Humans; Models, Cardiovascular; Prognosis; Renal Circulation; Splanchnic Circulation
PubMed: 28862947
DOI: 10.1161/JAHA.117.006817 -
Anesthesiology 1965
Review
Topics: Blood Circulation; Female; Humans; Infant; Infant, Newborn; Parturition; Respiration
PubMed: 14313462
DOI: 10.1097/00000542-196507000-00016 -
Seminars in Nuclear Medicine Apr 1976The techniques of tracer dilution in the circulation, and of tracer uptake by and washout from an orgen, may be described using expressions that are general and are not... (Review)
Review
The techniques of tracer dilution in the circulation, and of tracer uptake by and washout from an orgen, may be described using expressions that are general and are not dependent on specific models such as exponentials. The expressions have been applied to the measurement of cardiac output using impulse and constant rate injection techniques. Further expressions have been given for estimating organ blood flow from inflow/outflow concentration-time curves, and from the distribution of deposited tracer. Some problems with respect to the use of deposition techniques as they are ordinarily applied to the estimation of regional blood flow must be considered, particularly when there are capillary beds in series or where there is countercurrent diffusional shunting of diffusible tracers between inflow and outflow. This review deals with these various aspects of tracer theory as they relate to the measurement of blood flow.
Topics: Blood Circulation; Brain; Capillaries; Cardiac Output; Coronary Circulation; Humans; Microspheres; Radioisotope Dilution Technique; Radioisotopes; Regional Blood Flow
PubMed: 775641
DOI: 10.1016/s0001-2998(76)80002-5 -
American Journal of Physiology.... May 2002Muscle blood flow is regulated to meet the metabolic needs of the tissue. With the vasculature arranged as a successive branching of arterioles and the larger, >50... (Review)
Review
Muscle blood flow is regulated to meet the metabolic needs of the tissue. With the vasculature arranged as a successive branching of arterioles and the larger, >50 microm, arterioles providing the major site of resistance, an increasing metabolic demand requires the vasodilation of the small arterioles first then the vasodilation of the more proximal, larger arterioles. The mechanism(s) for the coordination of this ascending vasodilation are not clear and may involve a conducted vasodilation and/or a flow-dependent response. The close arteriolar-venular pairing provides an additional mechanism by which the arteriolar diameter can be increased due to the diffusion of vasoactive substances from the venous blood. Evidence is presented that the venular endothelium releases a relaxing factor, a metabolite of arachidonic acid, that will vasodilate the adjacent arteriole. The stimulus for this release is not known, but it is hypothesized that hypoxia-induced ATP release from red blood cells may be responsible for the stimulation of arachidonic release from the venular endothelial cells. Thus the venous circulation is in an optimal position to monitor the overall metabolic state of the tissue and thus provide a feedback regulation of arteriolar diameter.
Topics: Animals; Arterioles; Blood Circulation; Rats; Venules
PubMed: 11959667
DOI: 10.1152/ajpregu.00744.2001 -
British Medical Journal Mar 1966
Topics: Blood Circulation; Eye Diseases; Humans; Retinal Vessels
PubMed: 5907312
DOI: No ID Found -
European Journal of Vascular and... May 2001There are many reports of how IPC is used effectively in the clinical setting; including the prevention of deep venous thrombosis, improvement of circulation in patients... (Review)
Review
There are many reports of how IPC is used effectively in the clinical setting; including the prevention of deep venous thrombosis, improvement of circulation in patients with lower extremity arterial diseases, reduction of lymphoedema, and the healing of venous ulcers. However, despite the widely accepted use of IPC, it is still unclear how IPC actually exerts its beneficial effects. The exact physiological mechanisms of action are unknown. The clinical utility of IPC and the putative mechanisms by which IPC could exert its therapeutic effect will be reviewed. The paper will examine the mechanical effects of IPC exerted on the lower extremity, and the subsequent biochemical changes in the circulation. In vitro studies of the effects of mechanical stress such as compressive strain and shear on cultured endothelial cells, and their clinical relevance to IPC will also be reviewed.
Topics: Adult; Biomechanical Phenomena; Blood Circulation; Blood Vessels; Gravity Suits; Humans; Venous Thrombosis
PubMed: 11352511
DOI: 10.1053/ejvs.2001.1348 -
Acta Pharmacologica Sinica Oct 2010
Topics: Biology; Biomedical Research; Blood Circulation; Blood Vessels; Cardiovascular Diseases; Heart; Humans
PubMed: 20921953
DOI: 10.1038/aps.2010.179 -
Brazilian Journal of Medical and... Sep 2002There is a close association between the location of angiotensin (Ang) receptors and many important brain nuclei involved in the regulation of the cardiovascular system.... (Review)
Review
There is a close association between the location of angiotensin (Ang) receptors and many important brain nuclei involved in the regulation of the cardiovascular system. The present review encompasses the physiological role of Ang II in the brainstem, particularly in relation to its influence on baroreflex control of the heart and kidney. Activation of AT1 receptors in the brainstem by fourth ventricle (4V) administration to conscious rabbits or local administration of Ang II into the rostral ventrolateral medulla (RVLM) of anesthetized rabbits acutely increases renal sympathetic nerve activity (RSNA) and RSNA baroreflex responses. Administration of the Ang antagonist Sarile into the RVLM of anesthetized rabbits blocked the effects of Ang II on the RSNA baroreflex, indicating that the RVLM is the major site of sympathoexcitatory action of Ang II given into the cerebrospinal fluid surrounding the brainstem. However, in conscious animals, blockade of endogenous Ang receptors in the brainstem by the 4V AT1 receptor antagonist losartan resulted in sympathoexcitation, suggesting an overall greater activity of endogenous Ang II within the sympathoinhibitory pathways. However, the RSNA response to airjet stress in conscious rabbits was markedly attenuated. While we found no effect of acute central Ang on heart rate baroreflexes, chronic 4V infusion inhibited the baroreflex and chronic losartan increased baroreflex gain. Thus, brainstem Ang II acutely alters sympathetic responses to specific afferent inputs thus forming part of a potentially important mechanism for the integration of autonomic response patterns. The sympathoexcitatory AT1 receptors appear to be activated during stress, surgery and anesthesia.
Topics: Angiotensin II; Angiotensin Receptor Antagonists; Animals; Baroreflex; Blood Circulation; Blood Pressure; Brain Stem; Kidney; Losartan; Medulla Oblongata; Rabbits; Rats; Receptor, Angiotensin, Type 1; Sympathetic Nervous System
PubMed: 12219176
DOI: 10.1590/s0100-879x2002000900005 -
Advances in Physiology Education Sep 2005Research shows that misconceptions about human blood circulation and gas exchange persist across grade levels. The purpose of this study was twofold: 1) to investigate... (Comparative Study)
Comparative Study
Research shows that misconceptions about human blood circulation and gas exchange persist across grade levels. The purpose of this study was twofold: 1) to investigate the prevalence and persistence of blood circulation misconceptions among prospective elementary teachers and 2) to evaluate the effectiveness of learning activities for discovering what students know and can explain about blood circulation and lung function. The context was an undergraduate introduction to biology course taught by two professors across three semesters at a state university. Independent reviewers identified five categories of erroneous ideas about blood circulation. Many categories still presented problems to students at the end of the course: 70% of prospective elementary teachers did not understand the dual blood circulation pathway, 33% were confused about blood vessels, 55% had wrong ideas about gas exchange, 19% had trouble with gas transport and utilization, and 20% did not understand lung function. Results show that an interview about a drawing as a final exam was significantly better at revealing different errors and a higher frequency of erroneous ideas compared with an essay exam. There is an urgent need for instructional tools to help undergraduate students realize the discrepancies between their own ideas about blood circulation and those of the scientific community.
Topics: Adolescent; Adult; Blood Circulation; Cardiovascular Physiological Phenomena; Comprehension; Faculty; Female; Humans; Male; Prevalence; Schools; Students; Teaching
PubMed: 16109797
DOI: 10.1152/advan.00022.2004