Cardiovascular System: Part II

2019 ◽  
Author(s):  
Vanetta Levesque
Keyword(s):  
Blood Flow ◽  
Blood Volume ◽  
Hormonal Regulation ◽  
Blood Circulation ◽  
Venous Return ◽  
Regional Blood Flow ◽  
The Body ◽  
Venous Capacitance ◽  
System Part ◽  
The Right

This chapter gives an overview of blood circulation, then focuses on regional blood flow to a number of organs, and ends with a description of the microcirculation. It begins with venous return and blood volume. Most blood volume is contained within the venous system, and the chapter describes several mechanisms that allow for this volume of blood to be returned to the right heart. Next it describes the various means by which the blood circulation and volume are controlled. The chapter devotes considerable time describing the central, peripheral, and hormonal regulation of circulation and blood volume. Next, regional blood flow is described. Blood flow in different regions of the body is usually autoregulated, and variably controlled by the autonomic nervous system, and various humoral agents. The final section describes the mechanism by which blood flow in the microcirculation delivers nutrients, and removes wastes from the tissue by diffusion. Also described are the regulation of the microcirculation by pre and post capillary sphincters, and the effect of viscosity. This review contains 5 figures, and 40 references.  Keywords: venous return, vascular compliance, venous capacitance, vasomotor center, hypothalamic-pituitary-adrenal axis (HPA), microcirculation, regional blood flow, mixed venous oxygen saturation

Regional blood flow measurement in vivo for a definable geometry

1964 ◽  
Vol 206 (5) ◽  
pp. 962-966 ◽  
Author(s):  
Marvin B. Bacaner ◽  
James S. Beck
Keyword(s):  
Blood Flow ◽  
Flow Measurement ◽  
Necessary Conditions ◽  
Regional Blood Flow ◽  
The Body ◽  
Continuous Measure ◽  
Radioisotope Method ◽  
Arterial Concentration ◽  
Regional Concentration

A radioisotope method for measuring regional blood flow in the intestine of the dog in vivo has been favorably compared with measurement by timed collection of total venous outflow. The necessary conditions are a continuous measure of arterial concentration and cumulative regional concentration of radioisotope, an experimentally definable region, and temporary complete retention of tracer. The derivation of the relations used suggests additional applications of the method to other regions of the body.

scholarly journals Nonlinear analysis of fluctuations of microcirculation parameters in symmetrical organs of humans by laser doppler flowmetry

2019 ◽  
Vol 17 (4) ◽  
pp. 33-38 ◽  
Author(s):  
L. V. Mezentseva
Keyword(s):  
Nonlinear Dynamics ◽  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Coefficient Of Variation ◽  
Correlation Dimension ◽  
The Body ◽  
Doppler Flowmetry ◽  
Average Value ◽  
Flow Fluctuations ◽  
The Right

Purpose– the study the nonlinear dynamics of microcirculation parameters in human symmetrical organs.Material and Methods. Parameters of microcirculation were measured in healthy volunteers (aged between 50 and 70 years) by means of laser Doppler flowmetry (LDF). LDF signal transducers were fixed symmetrically on the lower parts of the right and left shoulders (3 cm above the elbow bend). The degree of chaoticity of microcirculation parameters as a nonlinear dynamic process was estimated using Hausdorff’s index, relative entropy and characteristics of phase portraits. Along with components of the amplitude-and-frequency range for blood flow fluctuations (myogenic, neurogenic, respiratory, and cardiac) was estimated and correlations between all characteristics of microcirculation in both sides of the body were done.Results.Asymmetry of correlation relationships of nonlinear dynamics parameters and components of the amplitude-andfrequency range for blood flow fluctuations of right and left sides of the body was revealed. Hausdorff index in the left side correlated not only with the average value of perfusion and with the coefficient of variation in the same side (r1 = –0,68; r2 =–0,51), but also with correlation dimension of chaos in the opposite side (r=0,49). Similarly, entropy in the left side correlated not only with the average value of perfusion and coefficient of variation in the left (r1 =0,43; r2 =0,60), but also with the entropy and correlation dimension of chaos in the right side (r1 =0,48; r2 =–0,41). The neurogenic component in the left side positively correlated with the myogenic component in the same side (r=0,71). A positive correlation was observed between the neurogenic component in right side and myogenic component in the opposite side (r=0,57). Asymmetry of correlation relationships was also revealed for the respiratory and cardiac components.Conclusions. Our results illustrate the specific regulation of blood flow in micro vessels of paired organs, which is associated with functional asymmetry. The physiological mechanisms for this asymmetry require further experimental and clinical studies. 

Comparative effects of vasodilator drugs on flow distribution and venous return

1985 ◽  
Vol 63 (11) ◽  
pp. 1345-1355 ◽  
Author(s):  
R. I. Ogilvie
Keyword(s):  
Blood Flow ◽  
Blood Volume ◽  
Time Constant ◽  
Venous Return ◽  
Flow Distribution ◽  
Fast Time ◽  
Central Blood Volume ◽  
Slow Time ◽  
Arterial Resistance ◽  
Slow Time Constant

Systemic vascular effects of hydralazine, prazosin, captopril, and nifedipine were studied in 115 anesthetized dogs. Blood flow [Formula: see text] and right atrial pressure (Pra) were independently controlled by a right heart bypass. Transient changes in central blood volume after an acute reduction in Pra at a constant [Formula: see text] showed that blood was draining from two vascular compartments with different time constants, one fast and the other slow. At three dose levels producing comparable reductions in systemic arterial pressure (30–40% at the highest dose), these drugs had different effects on flow distribution and venous return. Hydralazine and prazosin had parallel and balanced effects on arterial resistance of the two vascular compartments, and flow distribution was unaltered. Captopril preferentially reduced arterial resistance of the compartment with a slow time constant for venous return (−26 ± 6%, −30 ± 6%, −50 ± 5% at 0.02, 0.10, and 0.50 mg∙kg−1∙h−1, respectively; [Formula: see text]) without altering arterial resistance of the fast time-constant compartment. Blood flow to the slow time-constant compartment was increased 43 ± 14% at the highest dose, and central blood volume was reduced 108 ± 15 mL. In contrast, nifedipine had a balanced effect on arterial resistance with the lowest dose (0.025 mg/kg) but caused a preferential reduction in arterial resistance of the fast time-constant compartment at higher doses (−38 ± 4% and −55 ± 2% at 0.05 and 0.10 mg/kg, respectively). Blood flow to the slow time-constant compartment was reduced 36 ± 5% at the highest dose of nifedipine, and central blood volume was increased 66 ± 12 mL. Total systemic venous compliance was unaltered or slightly reduced by each of the four drugs. These results add further evidence to the hypothesis that peripheral blood flow distribution is a major determinant of venous return to the heart.

scholarly journals Steep head-down tilt has persisting effects on the distribution of pulmonary blood flow

2006 ◽  
Vol 101 (2) ◽  
pp. 583-589 ◽  
Author(s):  
A. Cortney Henderson ◽  
David L. Levin ◽  
Susan R. Hopkins ◽  
I. Mark Olfert ◽  
Richard B. Buxton ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Normal Subjects ◽  
Relative Dispersion ◽  
Lung Water ◽  
Before And After ◽  
Capillary Pressures ◽  
The Right

Head-down tilt has been shown to increase lung water content in animals and alter the distribution of ventilation in humans; however, its effects on the distribution of pulmonary blood flow in humans are unknown. We hypothesized that head-down tilt would increase the heterogeneity of pulmonary blood flow in humans, an effect analogous to the changes seen in the distribution of ventilation, by increasing capillary hydrostatic pressure and fluid efflux in the lung. To test this, we evaluated changes in the distribution of pulmonary blood flow in seven normal subjects before and after 1 h of 30° head-down tilt using the magnetic resonance imaging technique of arterial spin labeling. Data were acquired in triplicate before tilt and at 10-min intervals for 1 h after tilt. Pulmonary blood flow heterogeneity was quantified by the relative dispersion (standard deviation/mean) of signal intensity for all voxels within the right lung. Relative dispersion was significantly increased by 29% after tilt and remained elevated during the 1 h of measurements after tilt (0.84 ± 0.06 pretilt, 1.09 ± 0.09 calculated for all time points posttilt, P < 0.05). We speculate that the mechanism most likely responsible for our findings is that increased pulmonary capillary pressures and fluid efflux in the lung resulting from head-down tilt alters regional blood flow distribution.

Evidence for a dorso-medial parietal system involved in mental transformations of the body

1996 ◽  
Vol 76 (3) ◽  
pp. 2042-2048 ◽  
Author(s):  
E. Bonda ◽  
S. Frey ◽  
M. Petrides
Keyword(s):  
Blood Flow ◽  
Parietal Cortex ◽  
Human Subjects ◽  
Body Position ◽  
The Body ◽  
Right Hand ◽  
Positron Emission ◽  
Superior Parietal Cortex ◽  
The Right ◽  
Mental Transformations

1. The neural systems underlying body-space mental representation were studied by measuring changes in regional cerebral blood flow (CBF) with positron emission tomography in human subjects. 2. The experimental paradigm involved identification of the left or the right hand of the experimenter presented in different orientations or the palm of the subject's right hand. The subjects were required to decide whether it was the left or the right hand that was presented. To perform this task, the subjects had to move mentally the position of their own arm to adopt that of the experimenter's arm. The control condition involved the same type of tactual stimulation without the requirement of mental transformations of the subject's body position. The distribution of CBF was measured by means of the water bolus H2(15)O methodology during the performance of these tasks. 3. Comparison of the distribution of CBF between the experimental and control tasks was carried out to reveal changes specific to the mental transformations of the subject's body. Significant blood flow increases were observed in the caudal superior parietal cortex, including the intraparietal sulcus, and the adjacent medial parietal cortex. These findings demonstrated that there is a dorsomedially directed parietal system underlying mental transformations of the body in interactive relation with external space.

Breast Cancer: Regional Blood Flow and Blood Volume Measured with Magnetic Susceptibility–based MR Imaging—Initial Results

Radiology ◽  
2002 ◽  
Vol 223 (2) ◽  
pp. 558-565 ◽  
Author(s):  
Jean-Paul Delille ◽  
Priscilla J. Slanetz ◽  
Eren D. Yeh ◽  
Daniel B. Kopans ◽  
Leoncio Garrido
Keyword(s):  
Breast Cancer ◽  
Blood Flow ◽  
Magnetic Susceptibility ◽  
Mr Imaging ◽  
Blood Volume ◽  
Regional Blood Flow ◽  
Initial Results

scholarly journals Effect of Astrocytic Energy Metabolism Depressant on 14C-Acetate Uptake in Intact Rat Brain

2004 ◽  
Vol 24 (2) ◽  
pp. 188-190 ◽  
Author(s):  
Rie Hosoi ◽  
Maki Okada ◽  
Jun Hatazawa ◽  
Antony Gee ◽  
Osamu Inoue
Keyword(s):  
Blood Flow ◽  
Energy Metabolism ◽  
Rat Brain ◽  
Regional Blood Flow ◽  
Regional Distribution ◽  
Acetate Uptake ◽  
Minute Period ◽  
Intact Brain ◽  
The Right

Fluorocitrate, a selective astrocytic toxin, was microinjected into the right striatum of rat brain, and the regional distribution of 14C-acetate was measured using autoradiography. A significant reduction (more than 80%) in 14C-acetate uptake over a 5-minute period was observed in the right striatum, compared with that in the left striatum (saline infused), 4 hours after fluorocitrate (1 nmol/μL) infusion. This effect was transient, and 14C-acetate uptake had almost returned to normal at 24 hours after the fluorocitrate infusion. In contrast, the regional blood flow in the striatum, as determined using 14C-iodoamphetamine, was significantly increased by the fluorocitrate infusion. The present observations indicate that 14C-acetate uptake might be a useful characteristic for examining astrocytic energy metabolism in the intact brain.

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