Modeling renal hemodynamics e bruce pitman buffalo
1 / 23

Modeling Renal Hemodynamics - PowerPoint PPT Presentation

  • Updated On :

Modeling Renal Hemodynamics E. Bruce Pitman (Buffalo). Harold Layton (Duke) Leon Moore (Stony Brook). The Human Kidneys:. are two bean-shaped organs, one on each side of the backbone represent about 0.5% of the total weight of the body

Related searches for Modeling Renal Hemodynamics

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Modeling Renal Hemodynamics' - Sophia

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Modeling renal hemodynamics e bruce pitman buffalo l.jpg

Modeling Renal HemodynamicsE. Bruce Pitman (Buffalo)

Harold Layton (Duke)

Leon Moore (Stony Brook)

The human kidneys l.jpg
The Human Kidneys:

  • are two bean-shaped organs, one on each side of the backbone

  • represent about 0.5% of the total weight of the body

  • but receive 20-25% of the total arterial blood pumped by the heart

  • Each contains from one to two million nephrons

In 24 hours the kidneys reclaim l.jpg
In 24 hours the kidneys reclaim:

  • ~1,300 g of NaCl (~97% of Cl)

  • ~400 g NaHCO3 (100%)

  • ~180 g glucose (100%)

  • almost all of the180 liters of water that entered the tubules (excrete ~0.5 l)

Water secretion l.jpg
Water secretion

  • Release of ADH is regulated by osmotic pressure of the blood.

  • Dehydration increases the osmotic pressure of the blood, which turns on the ADH -> aquaporin pathway.

    • The concentration of salts in the urine can be as much as four times that of blood.

  • If the blood should become too dilute, ADH secretion is inhibited

    • A large volume of watery urine is formed, having a salt concentration ~ one-fourth of that of blood

Experiment pressure from a normotensive rat l.jpg
Experimentpressure from a normotensive rat

Experiment pressure spectra from normotensive rats l.jpg
Experimentpressure spectra from normotensive rats

Basics of modeling l.jpg
Basics of modeling

In all tubules and interstitium, balance laws for

  • chloride

  • sodium

  • potassium

  • urea

  • water

  • others

Basics of modeling ii l.jpg
Basics of modeling II

Simplifying assumptions

  • infinite interstitial bath

  • infinitely high permeabilities

  • chloride as principal solute driver

Basics of modeling iii l.jpg
Basics of modeling III

  • Macula Densa samples fluid as it passes

  • Feedback relation noted at steady-state

  • We assume the same form in a dynamic model

Basics of modeling iv l.jpg
Basics of modeling IV

  • Single PDE for chloride

  • Empirical velocity relationship: apply steady-state relation to dynamic setting

Flow rate



Model l.jpg

  • Steady-state solution exists

  • Idea: Linearize about this steady solution

  • Look for exponential solutions

Basic analysis18 l.jpg
Basic Analysis

  • If the real part of λ>0, perturbation grows in time. If Imaginary part of λ≠0, oscillations. [unstable]

  • If the real part of λ<0, perturbation decays in time. [stable]

To be done l.jpg
To Be Done

  • Complex perhaps chaotic behavior at high gain

  • Have 2 coupled nephrons. Need full examination of bifurcation

  • Need many coupled nephrons (O(1000))

  • Reduced model

2 nephron model l.jpg
2-nephron model

  • as many as 50% of the nephrons in the late CRA are pairs or triples

  • some evidence of whole organ signal at TGF frequency