Quantitative Renal Phys or Eval of Renal Fuction (Rao) Flashcards
Mass flow =
formula
concentration x rate of flow
expression od solute movements as a function of time
For solutes that are ingested and metabolized… (i.e. glucose)
rate of output =
rate of intake + rate of production - metabolism
For solutes that are produced only by metabolism… (i.e uric acid, urea)
rate of output =
Rate of production
For solutes that are not producedin the body… (i.e NaCl)
rate of output =
rate of intake
T or F: Urea can be excreted in sweat and feces.
F: only in urine
What are the 3 routes for kidney output?
renal vein, lymphatic, urine
Mass flow in the kidney =
rate of flow in renal vein + lymphatics + urine x the conc in enal vein + lymphatics + urine
Water input to the kidney is the same as ______ into the kidney
plasma flow
In a healthy nephron:
Filtration + secretion =
reabsorption + excretion
*input = output
Filtration rate =
GFR X Px
Excretion rate =
UF x Ux
What are the 3 parameters that quantify kidney function?
GFR
plasma clearence of solutes
renal blood flow
Why is inulin the model for measuring kidney function?
it is not produced in the body it is not metabolized it is excreted only in the kidney not secreted by tubule not reabs by tubule
What is the formula for GFR?
GFR = UF x Ux/Px
What is the volume of plasma that is completely cleared of the substance by the kidneys per unit time?
clearance
What effect does increased reabs have on clearance
decreases it
What effect does increased secretion have on clearance
increases it
What does a low clearance for a solute indicate?
it is reabs
What does a high clearance for a solute indicate?
it is secreted
What is the formula for extraction ratio?
Ex ratio = (Ax -Vx)/Ax
What does the extraction ratio measure?
the % of substance removed from the plasma
WIll a substance that is reabs have a high or low extraction ratio?
low
WIll a substance that is secreted have a high or low extraction ratio?
high
T or F: If a substance X is cleared completely from the plasma the clearance will equal the venous plasma concentraton
F: Cx = total renal plasma flow (when a substance is cleared completely)
What is the extraction ratio of PAH (para amino hippuric acid)
~1
*90-95% clearance
T or F: Cx of PAH = RPF
T: bc PAH is cleared completely
If GFR increases, plasma creatinine will (inc, decrease, stay the same).
decreases
T or F: decreasing GFR by 1/2 has very little effect on plasma creatinine levels
F: there is a mechanism for compensation of dec GRF… but after 50% you will see an sharp increase in plasma creatinine bc the threshold will be reached
