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ducts course
glom > prox convoluted tubule / distal convoluted tubule / collecting duct / pyramid / pelvis / ureter
ureters course
under uterine aretery / under ductus deferens (retroperitoneal)
fluid compartments
weight = 60% water -> 1/3 = extracellular + 2/3 intracellular // extracellular = 1/4 plasma + 3/4 interstitial // 60-40-20 = total-ICF-ECF
plasma volume measured by
radiolabeled albumin
extracellular volume measured by
inulin
normal plasma osmolarity
290 mOsm
glomerular barrier components
fenestrated cap epithelium (size) / basement membran with heparan sulfate (negative charge) / epithelial of podocyte foot processes
nephrotic syndrome vs glom barrier
loses charge barrier -> albuminuria / hypoproteinemia / generalized edema/ hyperlipidemia
renal clearance formula
C (clearance of X in mL/min) = Ux(urine conc) * V (urine flow rate) / Px (plasma conc of x)
Cx < GFR
net tubular reabsorption
Cx > GFR
net tubular secretion
clearance definition
volume of plasma from which the substance is completely cleared per unit time
GFR measured using
inulin -> freely filtered and neithter reabsorbed nor secreted // creatinine = approximate (overestimate -> moderately secreted in tubules)
GFR formula
U x V/P of inulin (=clearance of inulin)
ERFP defined
effective renal plasma flow -> estimated using PAH (filtered + actively secrete in proximal tubule -> all entering kidney is excreted)
ERFP formula
=U x V/P (of PAH) -> underestimates true RPF by ~10%
filtration fraction
=GFR / RPF
normal FF
~20%
filtered load formula
=GFR x plasma concentration
afferent constriction
dec RPF / dec GFR -> NC FF
efferent constriction
dec RPF / inc GFR -> inc FF
inc plasma protein concentration
NC RPF / dec GFR -> dec FF
dec plasma protein concentration
NC RPF / inc GFR -> inc FF
constriction of ureter
NC RPF / dec GFR -> dec FF
prostaglandins vs glom
dilate afferent arteriole // inhib by NSAIDS
A2 vs glom
constrict efferent arteriole // inhib by ACE inhibitors
excretion rate formula
V x U
reabsorption formula
filtered - excreted
secretion formula
exreted - filtered
glucose clearance
at normal level = completely reabs in prox tubule (Na/gluc cotransport) // 160-200 = glucosuria begins // 350 = fully saturated
amino acid clearance
Na-dep transporters (prox tubule) -> reabsorb by 3 distinct systems / competitive inhibition within each group
Hartnup\'s dz
deficiencny of neutral aa transporter (tryptophan) -> pellagra
Renin-angiotensin-aldo system (pathway)
angiotensin (liver) --(renin from kidney)-> angiotensin 1 --(ACE from lungs+kidneys)-> angiotensin 2
renin
from kidneys // stim by: dec BP (JG cells) / dec Na to kidney (MD cells) / inc sympathetic tone (B1 receptors)
AT2
vasoconstriction (inc BP) / constricts effect in glomb (inc FF) / stims aldo (adrenal) / stims ADH (post pit) / inc prox tubule Na/H activity / stim thirst (hypothalamus)
ANP
from atria in high volume / check on RAA? / -> relaxes vasc SM via cGMP -> inc GFR + dec Renin
ADH
osmolarity / low blood volume (precedence)
aldosterone
blood volume primarily (later ADH too)
JGA
JG cells + macula densa cells // defends glom filtration rate via RAA system
JG cells
modified smooth muscle of afferent arteriole // secrete renin in response to dec renal BP
macula densa cells
Na+ sensors in distal convoluted tubule // secrete renin in response to dec Na delivery
kidney endocrine secretions
epo / 1.25-OH2 vit D / renin / prostaglandins (PGE2)
erythropoietin
hypoxia -> released from interstitial cells in peritubular capillary bed
NSAIDs in acute renal failure
NSAIDS can cause acute renal failure -> inhibit renal production of prostaglandins = inhibit their keeping of afferent arterioles vasodilated to maintain GFR
1,25-vit D from kidney
proximal tubule cells covert 25-OH-D to 1.25-OH-D -> inc intestinal abs of  Ca + P // PTH stims this (1a-hydroxylase)
Renin from kidney
secreted by JG cells in (low arterial P + high renal sympathetics = B1 effect)
prostaglandins from kidney
paracrine secretion -> vasodilates afferent arterioles -> inc GFR
ANP vs kidney
from inc atrial P -> inc GFR + inc NA filtration (no inc reabs) // net = Na loss + volume loss
PTH vs kidney
from (dec Ca + inc PO4 + dec plasma 1.25 D) -> causes inc Ca reabs (DCT) + dec PO4 reabs (PCT) + inc 1.25 D production // also inc Ca + PO4 reabs from gut
AT2 vs kidney
from dec BP -> efferent arteriole constriction = inc GFR + inc FF + compensatory Na reabs in PCT+DCT // net = preservation of fn in low volume + Na reabs to prevent further loss
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