Glomerular physiology Flashcards
Glucose clearance
freely filtered
reabsorbed by renal tubules
-Na+/glucose cotransporter in PCT
plasma glucose > 160 -> max transport exceeded, starts to spill into urine
Over 350 transporters fully saturate -> a lot of glucose in urine
Amino acid clearance
Na+ - dependent transporters in PCT
Carrier systems - positive, negative, neutral aa
Neutral carrier deficiency -> hartnup dz
- no tryptophan to convert to niacin
- > dermatitis, diarrhea, dementia -> death
Fluid compartment distribution
Total body water 60%
ICF 40%
ECF 20% (25% of the ECF is plasma)
Renal clearance
plasma volume kidney can clear per unit of time
RC = (urine [X] x urine flow rate)/plasma [x]
Clearance less than GFR
some reabsorbed by tubules
Clearance > GFR
blood -> tubules -> substance secreted by tubules
inulin
freely filtered by glomeruli, not reabsorbed by renal tubules
not secreted by renal tubules
Used to calculate GFR
Clearance = GFR
Creatinine
freely filtered
not reabsorbed by tubules
tiny amount secreted by tubules
creatinine clearance - estimate of GFR
Renal plasma flow
estimate w/ para-aminohippuric acid (PAH)
filtered by glomerulus
actively secreted by proximal tubule
all PAH to kidney excreted
RPH = (Upah x urine flow rate)/ Ppah
filtration fraction
portion of blood to kidney filtered through glomerulus
FF = GFR/RPF
normally about 20%
Constriction of afferent arteriole affects on GFR, RPF, Filtration fraction
GFR down
RPF down
FF (GFR/RPF) no change
Constriction of efferent arteriole affects on GFR, RPF, Filtration fraction
GFR up
RPF down
FF (GFR/RPF) up
Dilation of afferent arteriole affects on GFR, RPF, Filtration fraction
GFR up
RPF up
FF (GFR/RPF) no change
dilation of efferent arteriole affects on GFR, RPF, Filtration fraction
GFR down
RPF up
FF (GFR/RPF) down
increase in serum protein affects on GFR, RPF, Filtration fraction
GFR down
RPF -
FF (GFR/RPF) down
