Jan3 M1-GFR Flashcards
cortex content
glomeruli, tubules
medulla content
collecting ducts, loop of Henle
embryo of nephron
two types of cells join in DCT
3 filtration layers at glomerulus from inside capillary to outside
endothelial layer, BM layer, foot processes of podocytes
podocytes are what
specialized epithelial cells
what filtrate does not contain
cells, proteins, fats*
max size of molecules going in filtrate
70 kDa (70 kg per mol)
albumin size + why not in filtrate
62 kDa. is negative. BM and podocytes are negative.
albumin of urine sign of what + 2 things that might have happened
glomerular disease.
damage to one of 3 layers OR loss of negative charge
how filterability of a substance varies with size and charge
less with bigger size.
positive > neutral > negative
clearance def
how much of a substance is removed from the circulation by the kidney and put into urine per unit time
GFR formula
K((Pgc - Pt) - (OPgc - OPt) = GFR
K in GFR formula
ultrafiltration coefficient (total capillary area available for filtration)
what can affect K
glomerular disease, immune complex deposition
what can affect Pgc
aff and eff R, diabetes, htn, CKD
what can affect Pt
tubular obstruction
what can affect OPgc
hypoalbuminemia, nephrotic syndrome
creatinine origin
creatine in muscle converted to Cr
Cr values needed to get GFR (or Crcl): what’s the formula
GFR x plasma conc Cr = urine conc Cr x urine volume
what urine volume to use in crcl or GFR formula
24 hour urine collection
how Cr varies with GFR
lower GFR = higher Cr (blood!!)
stage 1 CKD def
kidney damage, normal GFR, above 90
stage 2 CKD def
kidney damage, mild drop in GFR, 60-89
stage 3 CKD def
moderate drop in GFR. 30-59
stage 4 CKD def
severe drop in GFR. 15-29
stage 5 CKD def
ESRD. less than 15.
stage 5 CKD meaning
dialysis or need for dialysis or pre-dialysis
urinary creatinine qt for males and females
males 0.2 mmol per kg daily
females 0.15 mmol per kg daily
urinary creatinine used for what
check if complete 24 hr urine collection is done
real way of determining GFR
Cockroft Gault formula: use serum Cr only
(140-age)xweightx(1.2 if male)div.serum Cr
2 things to note about Cr and GFR
- have to be in steady state
2. CrCl overestimates GFR bc Cr secreted in PCT
normal GFR
100 ml per min
things that can affect Cr production (2)
meat intake and age (less muscle mass)
urea origin and absorption in tubule
comes from a.a metab
PCT
urea vs GFR
inversely proportional
urea and Cr in hypovolemia
urea rises much more than Cr so can assess patients with acute renal failure
range of renal autoregulation
BP 80 to 160
renal autoregulation goal
maintain GFR
renal autoregulation 5 components
myogenic, ATII (RAAS), SS, PGs, TG feedback
myogenic reflex of autoregul
low BP: AA dilates and EE constricts
high BP: AA constricts and EE dilates
components of juxtaglomerular apparatus
- macula densa cells of the DCT in contact with AA
2. juxtaglomerular cells (modified SM cells) in AA
TG feedback (3 steps)
- macula densa cells sense NaCl in DCT
- if too low, produce NO to dilate AA
- juxtaglomerular cells release renin if BP is low (sense low volume)
vasoconstriction in renal autoregul
SS reaction to drop in BP (SS: epinephrine causes vasoconstriction)
ATII (RAAS) in renal autoregul
renin leads to ATII prod.
ATII constricts EA more than AA
PGs in renal autoregul
PGs dilate the AA to preserve GFR
NSAIDs and GFR
NSAIDs block PGs so drop GFR
