Experimental and theoretical studies on vasculature and heat transfer in the rat spinotrapezius muscle.
Item
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Title
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Experimental and theoretical studies on vasculature and heat transfer in the rat spinotrapezius muscle.
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Identifier
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AAI9908365
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identifier
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9908365
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Creator
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Song, Ji.
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Contributor
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Advisers: Lisa X. Xu | Sheldon Weinbaum | Daniel E. Lemons
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Date
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1998
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Biomedical | Biology, Animal Physiology
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Abstract
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In this dissertation both experimental and theoretical studies were conducted to investigate microvascular heat exchange of thermally significant countercurrent artery-vein pairs in an exteriorized rat spinotrapezius tissue preparation. The vascular architecture of the spinotrapezius was first quantified. The blood flow in the artery of the countercurrent vessel pairs was then measured in normal and pharmacologically vasoconstricted and vasodilated states. The results were then used to evaluate the enhancement in the effective thermal conductivity ({dollar}k\sb{lcub}eff{rcub}{dollar}) due to blood perfusion according to the Weinbaum-Jiji theory. The scaling relations for the vascular architecture and blood flow were also explored. These relations were later used to extrapolate the blood flow in vessels greater than 130 {dollar}\mu{dollar}m diameter, where it was difficult to make direct optical measurements of blood flow velocity. Furthermore, the axial thermal equilibration between the countercurrent vessel pair and its surrounding tissue was studied in the spinotrapezius. The thermal disturbance caused by the vasodilated first-order vessel pair and its background tissue temperature field were measured and compared with theoretical predictions. Finally, the Weinbaum-Jiji {dollar}k\sb{lcub}eff{rcub}{dollar} theory for heat exchange between the paired vessels and their surrounding tissue was also examined. {dollar}k\sb{lcub}eff{rcub}{dollar} was estimated by the Weinbaum-Jiji theory and compared with the experimentally derived tissue thermal conductivity by approximating the tissue as a fin. The results of the current study indicate that countercurrent blood flow can produce a dramatic increase in tissue thermal conduction in the vasodilated state, and the Weinbaum-Jiji {dollar}k\sb{lcub}eff{rcub}{dollar} theory can be used to describe heat exchange of the countercurrent vessel pairs of the rat spinotrapezius muscle that are less than 200 {dollar}\mu{dollar}m in diameter.;Chapter 1 gives a brief background of blood-tissue heat exchange in the microcirculation and the basic concepts for scaling relations in biological systems. The effect of perfusion rate on blood-tissue heat exchange due is presented in Chapter 2. Chapter 3 describes the vascular scaling relations in the spinotrapezius muscle. The thermal equilibration between countercurrent vessel pairs and their surrounding tissue in spinotrapezius is investigated in Chapter 4. Finally, in Chapter 5 the conclusions have been drawn from the present study. Directions for future research are suggested.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
