04 Renal Physiology II

Function Measurements

_..

  • actual calculation

  • GFR: main number for kidney healthiness

_..

  • 40% going across glomerulus, 60% leaving kidney

  • actual calculation

  • GFR: main number for kidney healthiness

_..

  • how much Na going across glomeruli per min

_..

  • urine flow: how much urine kidney making

_..

  • urine flow rate: how much urine pt makes

Clearance

_..

  • urine concentration, urine flow rate , plasma concentration

  • kidney cleared 5 mole of Na OR

  • kidney cleared 1L of blood of Na

GFR

_..

  • inulin

  • creatinine

_..

  • all filtered inulin goes out of kidney

_..

  • naturally clearing, easier to do

_..

  • Volume flow cumbersome to determine

  • special formula to use

_..

  • 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

RPF

_..

  • 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

RBF

_..

_..

  • HCT = bottom red

Others

_..

Meds

_..

  • FF same: still filtering same percentage of blood

  • pt can go into renal failure/heart failure

_..

  • Ang II: constrict efferent, increase GFR, decrease RBF

Secretion and Absorption

_..

  • if filtered not = excretion, some must be either secreted or reabsorbed

_..

_..

_..

_..

  • 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

_..

_..

  • 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%

Practice Questions

_

  • clearance of inulin = GFR

Previous03 Renal Physiology 1Next05 Nephron Physiology

Last updated

Was this helpful?