renal physiology 2 Flashcards
clinically how can GFR be determined ?
through creatinine - closest naturally occurring substance to inlulin
what is the association between age and GFR ?
GFR declines with age
how is the renal plasma flow calculated ?
use PAH clearance
what is the GFR best estimated by ?
creatinine clearance
how is the renal clwarance calculated ?
C = (urine concentration x urine volume ) / plasma concentration
what are the different comparisons between the renal clearance and the GFR ?
Cx=GFR then no reabsorption of the substance only filtration
Cx>GFR then the substance is filtered and secreted
Cx<GFR the substance is both filtered and reabsorbed
what is the formula for the GFR ?
urine conc of inulin x urine volume flow rate
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plasma concentration of inulin
what is the normal GFR rate ?
100ml/min
how if the GFR calculated with the filtration coeffecient ?
Kf = (Pgc - Pbs ) -(πgc-πbs)
what chemical have an effect of the afferent and efferent arterioles in the kidney ?
afferent - normally dilated by prostaglandins this is inhibited by NSAIDs
efferent - normally constricted by angiotensin II , this is inhibited by ACE inhibitors
how is the renal blood flow calculated ?
1/(1-Hct)
how is the effective renal plasma flow calculated ?
Upah x Volume of urine
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plasma concentration of PAH
how is the filtration fraction calculated ?
GFR/RPF
how is the filtered load of substance X calculated ?
Plasma concentration of that substance multiplied by GFR
what is the clinical effect of using NSAIDS in renal disease?
decreased GFR , acute renal failure
how can we calculate the amount excreted of substANCE X ?
volume of urine multiplied by concentration in the urine
How is the filtered excretion calculated ?
urine concentration multiplied by the urine outflow rate
how do you calculate the excretion rate of a substance ?
excreted = filtered - reabsorbed + secreted
