Cardiovascular Dynamics

Rushmer, Robert F.

doi:10.1097/00000441-196201000-00035

Cited by 42 publications

(54 citation statements)

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“…Bone and its system correspond to the elastic mechanics (Cowin, 1981) and the structural mechanics. Blood and the circulation systems correspond to hydrodynamics (Burton, 1965;Rushmer 1970;Caro et al, 1978). Hydrodynamics is generally nonlinear, and is contacted with the limit cycle and various periods or quasiperiods, whose branch-chaos obtain fractal, and derive the Julia set.…”

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Chaos, Fractal in Biology, Biothermodynamics and Matrix Representation on Hypercycle

Chang¹

2013

Neuroquantology

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First, we discuss biofield and some nonlinear theories in biology. Next, chaos in biology and its application to cancer are researched. Third, fractal and complex dimension in biology are searched. Fourth, nonlinear biothermodynamics and in which possible entropy decrease are investigated. Fifth, we propose the matrix representations of hypercycle theory. Hypercycle can be defined by a degree of connectivity. Its fuzzy element corresponds to that each element is fractal. NeuroQuantology should be nonlinearity and quantization, and may relate to quantum chaos, quantized matrix, etc.

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confidence: 99%

Chaos, Fractal in Biology, Biothermodynamics and Matrix Representation on Hypercycle

Chang¹

2013

Neuroquantology

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“…Because cardiac output is directly related to cardiac preload (Starling's law of the heart) (27), cardiac output tends to decrease during head-up movements (25). Furthermore, cardiac output and peripheral vascular resistance determine systemic blood pressure, such that the sympathetic nervous system must produce a rapid net increase in peripheral resistance by inducing vasoconstriction at the onset of head-up body rotations to maintain stable blood pressure (7).…”

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Effects of postural changes and removal of vestibular inputs on blood flow to and from the hindlimb of conscious felines

Yavorcik¹,

Reighard²,

Misra³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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September 30, 2009; doi:10.1152 doi:10. /ajpregu.00551.2009 show that the vestibular system contributes to blood pressure regulation. Prior studies reported that lesions that eliminate inputs from the inner ears attenuate the vasoconstriction that ordinarily occurs in the hindlimbs of conscious cats during head-up rotations. These data led to the hypothesis that labyrinthine-deficient animals would experience considerable lower body blood pooling during head-up postural alterations. The present study tested this hypothesis by comparing blood flow though the femoral artery and vein of conscious cats during 20 -60°head-up tilts from the prone position before and after removal of vestibular inputs. In vestibular-intact animals, venous return from the hindlimb dropped considerably at the onset of head-up tilts and, at 5 s after the initiation of 60°rotations, was 66% lower than when the animals were prone. However, after the animals were maintained in the head-up position for another 15 s, venous return was just 33% lower than before the tilt commenced. At the same time point, arterial inflow to the limb had decreased 32% from baseline, such that the decrease in blood flow out of the limb due to the force of gravity was precisely matched by a reduction in blood reaching the limb. After vestibular lesions, the decline in femoral artery blood flow that ordinarily occurs during head-up tilts was attenuated, such that more blood flowed into the leg. Contrary to expectations, in most animals, venous return was facilitated, such that no more blood accumulated in the hindlimb than when labyrinthine signals were present. These data show that peripheral blood pooling is unlikely to account for the fluctuations in blood pressure that can occur during postural changes of animals lacking inputs from the inner ear. Instead, alterations in total peripheral resistance following vestibular dysfunction could affect the regulation of blood pressure.blood flow patterning; venous return; cardiac output; orthostatic hypotension HEAD-UP BODY ROTATIONS in humans or animals typically result in some pooling of blood in the periphery and a resulting reduction in return of blood to the heart. Because cardiac output is directly related to cardiac preload (Starling's law of the heart) (27), cardiac output tends to decrease during head-up movements (25). Furthermore, cardiac output and peripheral vascular resistance determine systemic blood pressure, such that the sympathetic nervous system must produce a rapid net increase in peripheral resistance by inducing vasoconstriction at the onset of head-up body rotations to maintain stable blood pressure (7). Arterial baroreceptor mechanisms play an important role in regulating peripheral vasoconstriction during postural alterations (23). In addition, there is considerable evidence from studies in animals (6,8,10,11,21,22,32) and humans (1,4,12,23,26,28,30) that the vestibular system also participates in triggering increases in vasomotor activity during movements that promote peripheral blood pooling...

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“…Not only would the enlarged heart be energetically costly, it would also be grossly ine¤cient because a greater proportion of energy would be used to deform the heart muscle itself and less could be used to propel the blood (Rushmer 1970;Weber et al 1986). In the human heart, about 10% of the total energy is used to overcome ventricular wall sti¡ness, compared to up to 25% to move the blood (Van Citters et al 1957).…”

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Hearts, neck posture and metabolic intensity of sauropod dinosaurs

Seymour

Lillywhite

2000

Proc. R. Soc. Lond. B

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Hypothesized upright neck postures in sauropod dinosaurs require systemic arterial blood pressures reaching 700 mmHg at the heart. Recent data on ventricular wall stress indicate that their left ventricles would have weighed 15 times those of similarly sized whales. Such dimensionally, energetically and mechanically disadvantageous ventricles were highly unlikely in an endothermic sauropod. Accessory hearts or a siphon mechanism, with sub-atmospheric blood pressures in the head, were also not feasible. If the blood £ow requirements of sauropods were typical of ectotherms, the left-ventricular blood volume and mass would have been smaller; nevertheless, the heart would have su¡ered the serious mechanical disadvantage of thick walls. It is doubtful that any large sauropod could have raised its neck vertically and endured high arterial blood pressure, and it certainly could not if it had high metabolic rates characteristic of endotherms.

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Cardiovascular Dynamics

Cited by 42 publications

References 0 publications

Chaos, Fractal in Biology, Biothermodynamics and Matrix Representation on Hypercycle

Chaos, Fractal in Biology, Biothermodynamics and Matrix Representation on Hypercycle

Effects of postural changes and removal of vestibular inputs on blood flow to and from the hindlimb of conscious felines

Hearts, neck posture and metabolic intensity of sauropod dinosaurs

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