GFR and RBF Flashcards
What is glomerular filtration, and thus GFR, dependent on?
NET filtration pressure (Starling forces)
Why might filtration occur in the afferent end of the glomerulus but not in the efferent end?
NET filtration differences between the two
As filtration occurs, plasma oncotic pressure increases, negating the NET pressure
In order to maintain filtration throughout the entire glomerulus, what is needed?
Why?
Increased RBF
Maintain high capillary hydrostatic pressure, thus keeping the NET filtration pressure > zero
Other than Starling forces, what else affects GFR?
Capillary permeability and surface area
4 ways in which GFR can be altered by the body
Alter Kf - mesangial cell contraction
Alter BP
Alter afferent resistance
Alter efferent resistance
How to mesangial cells affect Kf and thus GFR?
Contraction - shortens capillary loops, decreases S.A.
How does afferent constriction affect:
Glomerular hydrostatic pressure
GFR
RBF
Decreased RBF
Decreased pressure
Decreased GFR
How does efferent constriction affect:
Glomerular hydrostatic pressure
GFR
RBF
Increased pressure (pooling)
Increased GFR
Decreased RBF
How does efferent dilation affect:
Glomerular hydrostatic pressure
GFR
RBF
Increased RBF
Decreased pressure
Decreased GFR
How does afferent dilation affect:
Glomerular hydrostatic pressure
GFR
RBF
Increased RBF
Increased pressure
Increased GFR
Myogenic mechanism of autoregulation
Increased vascular stretch (high BP)
Calcium released
Causes contraction
An increased renal perfusion pressure will cause TG feedback to do what?
Increased GFR, thus increased NaCl in lumen
JG cells release adenosine to cause afferent vasoconstriction, thus drop in pressure and GFR
A decreased renal perfusion pressure will cause TG feedback to do what?
Drop in GFR, so drop in NaCl in lumen
Released Renin by granular cells for efferent constriction and NO for afferent dilation
