In my first post I offered this diagram to show a way to imagine what the solute transfer process would look like; I imagined each molecule of waste was a pixel of color: red the small easy to remove molecules potassium and phosphorus, green the harder to remove molecules phosphorus,beta2 microglobulin and homocystein, and blue the water and salts. This was in response to Dr. Agar's two part article on Home Dialysis Central(part 1; part 2) Fluid and solute removal: how and why.
I found the graph in the wikipedia commons, it happens to have a triangle inscribed around the D65 point but I can't think of what the triangle could represent if each molecule of waste is a pixel of color (keeping within the triangle to avoid washout?). For our purposes the D65 point can be relative, it can default to be the initial composition of the blood. Homeostasis, a balance between the chambers, would visually appear as all three compartments having the same color.
Rich asks what the yellow,lavender and aqua represents? The color shifts represent various color densities. All colors are comprised of some combination of the three primary colors - red, green and blue. If you add red and green the color becomes more yellow - in my analogy if the relative density of potassium and phosphorus increases the color would shift towards yellow. Conversely if blue is removed while the red and green stay constant the same shift towards yellow will happen.
If we say homeostasis is white then the color will shift towards red if the proportion of red molecules (urea, potasium) increases. As Dr. Agar pointed out phosphorus would be removed from the blood compartment faster than it could be replaced from the interstitium. This would mean that the interstitium would be more green than the blood compartment. In the case of water the color shift would depend on ones ultrafiltration rate. If the UFR was greater than 400ml/hour the blood compartment would shift towards yellow while the interstitium would shift towards teal.
I think animating this process would be very informative.
CIE 1931 xy chromaticity diagram showing the sRGB gamut and the D65 white point from wikipedia used under a Creative Commons license commons