04 Renal Physiology II
Last updated
Last updated
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actual calculation
GFR: main number for kidney healthiness
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40% going across glomerulus, 60% leaving kidney
actual calculation
GFR: main number for kidney healthiness
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how much Na going across glomeruli per min
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urine flow: how much urine kidney making
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urine flow rate: how much urine pt makes
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urine concentration, urine flow rate , plasma concentration
kidney cleared 5 mole of Na OR
kidney cleared 1L of blood of Na
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inulin
creatinine
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all filtered inulin goes out of kidney
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naturally clearing, easier to do
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Volume flow cumbersome to determine
special formula to use
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amount in urine = amount made in muscles
not a linear, straight line relationship
plasma Cr concentration, not urine concentration
use clearance equation to calculate GFR if given urine/plasma concentration and urine flow
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small amount goes to CT
everything in goes out, none in the efferent
calculate amt of blood filtered of PAH (clearance), one can find amt of blood enter kidney
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HCT = bottom red
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FF same: still filtering same percentage of blood
pt can go into renal failure/heart failure
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Ang II: constrict efferent, increase GFR, decrease RBF
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if filtered not = excretion, some must be either secreted or reabsorbed
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if put in 10 grams, must excrete 10 grams, otherwise accumulate
Normal:
5 in, 5 out, 4 plasma concentration
insult: can't excrete, 5 in, 2 out, plasma concentration go up to 6
new steady state, 5 in, 5 out, 6 plasma
new steady state concentration higher than original steady state
e.g. hyperkalemia, excreting same amount taking in
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filtered load: GFR x plasma concentration for urea is same
fractional excretion: excretion/filtered load, filtered load fallen, amt excreted is same
5 g filtered, 1 secreted, fractional excretion: 1/5
renal failure, GFR fallen
2 g filtered, 1g excreted, fractional excretion 50%
clearance of inulin = GFR
