Test2: Wk6: 2 Glomerular Hemodynamics - Puri Flashcards
renal nerves are
sympathetic
renal nerves do (4)
vasoconstriction
⬆ Renin Secretion
⬆ Na reabsorption
pain fibers
Mesangial Cells function
Maintain structural
architecture of
glomerulus
Mesangial Cells Dz
IgA nephropathy
Diabetic nephropathy
Glomerular endothelial cells function
Fenestrations and glycocalyx
facilitate selective permeability and filtration
Glomerular endothelial cells Diseases (4)
ANCA-associated GN
Lupus nephritis
Hemolytic uremic syndrome
Diabetic nephropathy
GBM (glomerular Basement Membrane) Function
Regulates filtration
GBM Disease
Goodpasture Syndrome
Podocytes Function
Foot processes wrap around capillaries; slit diaphragm regulates filtration
Podocytes Disease (3)
Minimal change disease
FSGS
Membranous Nephropathy
Parietal epithelial
cells Function
Line Bowman’s capsule
Parietal epithelial
cells Dz
Crescentic GN
The renal system has two arterials in — and two vascular beds in —
series; series
Total renal resistance is the sum of
afferent and efferent arteriolar resistances
Step 1 and Step 2
Step 1: filtration
Step 2: Reabsorbtion
Plasma filtration at the glomerulus; essential for
essential for filtration of toxic metabolites
Reabsorption of essential solutes into in the —
peritubular capillaries
Normal GFR
125mL/min to 180L/day
how many times per day is the entire ECF filtered
> 10x
Peritubular reabsorption
As the tubules resorb solutes, including Na+, glucose and amino
acids, they accumulate in the peritubular interstitial space. From this interstitial space the solutes have to re-enter the peritubular capillaries for return to the
circulation.
steps in Na reabsorption from urine to the blood
3
Step 1 in Na+ reabsorption from the urine to blood
Na+ crosses the lipid bilayer at the brush border by cotransport or antiport
Step 2 in Na+ reabsorption from the urine to blood
Na+ exits the cell at the basolateral border via the Na+,K+ ATPase
Step 3 in Na+ reabsorption from the urine to blood
Once Na (and water) is in the interstitial space it can be absorbed from interstitium into blood with fluid following the balance of Starling forces or can back-leak (4)
Glomerular filtration depends on balance of
hydrostatic and oncotic pressures
The hydrostatic (capillary pressure) is dependent on — and the — around the capillaries.
plasma flow and the resistance of arterioles
glomerular capillary hydrostatic pressure (PGC) is
60mmHg
peritubular capillaries pressure
15 mmHg
increase blood flow — is not reached
filtration equilibrium
constrict blood flow to AA what happens to blood flow in EA
decrease
constrict blood flow to EA what happens to blood flow in AA
decrease
reduced renal plasma flow will reduce — more than increased plasma flow will increase it
GFR
change filtration by (2 ways) both are changed by
1 capillary pressure
2 blood flow through the capillary
both changed by AA and EA
AA and EA control both
glomerular plasma flow and glomerular filtration rate
total renal resistance =
AA + EA
EA constriction GFR
will increase except when EA is constricted so much that that GFR falls - ex shock
AA Constriction
⬇ PGC
⬇ GFR
⬇ RBF
EA Constriction
⬆ PGC
⬆ GFR
⬇ RBF
EA Dilation
⬇ PGC
⬇ GFR
⬆ RBF
AA Dilation
⬆ PGC
⬆ GFR
⬆ RBF
always solve for — first
RPF
Filtration Fraction Equation FF =
FF = GFR / RPF
Filtration Fraction is
the percent of plasma water flowing through the glomerular capillary that is filtered
peritubular capillaries have — hydrostatic pressure
decreased
peritubular capillaries have — oncotic pressure
increased
increased oncotic pressure favors
reabsorption
High filtration fraction means
more plasma filtered at glomerulus and protein is more concentrated in peritubular capillaries
High filtration fraction = — = —
higher oncotic pressure = higher Na reabsorption
low filtration fraction = — = —
lower oncotic pressure = less Na reabsorption
FF for high Na diet
low
FF for low Na diet
high
— FF is desired during reduced MAP/ CO and reduced Na and vice a versa
high
4 Systems that regulate GFR/RPF and FF
- RAAS
- SNS
- Arginine Vasopressin AVP
- Atrial Natriuretic Peptide ANP
RAAS, SNS, and AVP — FF by and — Na
increase FF by constricting EA conserve Na
ANP dilates — and constricts — resulting in
AA, EA
⬆⬆ GFR
⬆ RPF
⬆FF
ANP is supposed to get rid of Na but increases FF
doesn’t change Na reabsorption at this step but effects the late nephron
Angiotensin II — both AA and EA but is preferential for — of —
constriction, constriction, EA
Angiotensin II is a strong
vosoconstrictor
Angiotensin II effect on GFR
GFR falls slightly or doesn’t change
maintain GFR
when is Angiotensin II activated
when volume depleted ➡ CO falls ➡ GFR decreases
SNS — GFR and RPF by — AA and EA resulting in — FF
decrease; constrict; increased
if SNS is maximally activated what happens
shut down kidney, massive constriction GFR is almost 0
what protects the kidney during state of SNS shock
prostaglandin system
— and — oppose vasoconstriction of AA induced by SNS and ANGII
PGI2 and PGE2 - dilate AA
NSAIDS during shock
block prostaglandins
NSIADS in kidney Dz
no
Tubuloglomerular feedback Mechanism
the myogenic response regulates GFR by negative feedback
Macula Densa produces (2)
Renin and ANGII
master regulator of Renal System
Macula Densa
Macula Densa is part of the — and touches the —
thick ascending limb, AA
Macula Densa exchanges information between
blood and urine
clearance estimates the volume of
plasma that contained that much of a substance at plasma concentration
clearance =
Clearance = Ux x V / Px
Filtered Load =
GFR x Plasma Conc.
Excreted load =
V x urine conc.
Fx > Ex
net tubular absorption
Fx < Ex
net tubular secretion
Ex = Ex
used to calculate GFR - inulin
increase plasma inulin concentration; what happens to inulin clearance
unchanged - inulin clearance is independent of plasma concentration
Creatinine is — related to GFR
inversely
Creatinine can be used to estimate
GFR
Creatinine — GFR by —
overestimate by 10%
if GFR falls plasma creatinine will
rise
Fractional excretion Na <1%
renal hypo-perfusion
fractional excretion Na >2%
acute tubular necrosis
