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Completely 3dimensional Simulation of Urine Concentrating Mechanism in Rat Outer Medulla

Sohrabi, Salman | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44034 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saidi, Mohammad Said; Firoozabadi, Bahar
  7. Abstract:
  8. The urine formation and excretion system has long been of interest for mathematicians and physiologists to elucidate the obscurities within the process happen in renal tissue. In this study, a novel and absolutely three-dimensional approach is utilized for modeling urine concentrating mechanism in rat renal outer medulla which is essentially focused on demonstrating the significance of tubule's architecture revealed in anatomic studies and physiological literature. Since nephrons and vasculatures work interdependently through a highly structured arrangement in outer medulla which is dominated by vascular bundles, a highly detailed functional unit is proposed and also it is strongly justified by means of many quantitative and qualitative experimental data. Due to minor influence of vasa rectas on medulla osmolality and osmolality gradients, central core assumption is employed. The model equations are based on 3 spatial dimensions mass, momentum and species transport equations as well as standard expressions for solutes and water transmural transport as tubule's boundary conditions. Thus, our model can perfectly simulate preferential interactions among different tubules and it is shown that such interactions definitely promote solute cycling and enhance urine concentrating capability. Indeed, with 3-D modeling, we would define no additional constraints to numerical simulation. The numerical results are completely consistent with tissue slice experiments and even our model predicts more coricomedullary osmolality gradient in outer medulla than previous equivalent 1-D simulations. The dominant feature of our model that distinguishes it from previous studies is that we have modeled this complex environment three dimensionally as it really takes place in the kidney tissue
  9. Keywords:
  10. Three-Dimensional Simulation ; Rat Renal Outer Medulla ; Urine Concentrating Mechanism ; Tubule's Architecture

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