1.3.1 Glomerular Filtration Function and Renal Blood Flow II Flashcards
What is the normal value for renal plasma flow (RPF)?
660 mL/min, 950 L/day
What is the normal value for glomerular filtration rate (GFR)?
125 mL/min, 180 L/day
What three factors influence ultrafiltration and ultimately the GFR?
Net filtration pressure, surface area, and permeability
What is the equation for GFR?
GFR = KUF * PUF
KUF (includes surface area and permeability)
PUF (net filtration pressure)
How does constriction of afferent arterioles affect blood flow resistance, RBF, and glomular capillary pressure? What is the net effect on GFR?
Increases blood flow resistance
Fall in RBF
Fall in glomerular capillary pressure
Net effect: Decrease in GFR
How does dilation of afferent arterioles affect blood flow resistance, RBF, and glomular capillary pressure? What is the net effect on GFR?
Drop in blood flow resistance
Rise in RBF
Rise in glomerular capillary pressure
Net effect: Increase in GFR
How does constriction of efferent arterioles affect blood flow resistance, RBF, and glomular capillary pressure? What is the net effect on GFR?
Increase blood flow resistance
Slows RBF (tends to reduce GFR)
Rise in glomerular capillary pressure (tends to increase GFR)
Net effect: Small rise in GFR
How does dilation of efferent arterioles affect blood flow resistance, RBF, and glomular capillary pressure? What is the net effect on GFR?
Decrease blood flow resistance
Increase RBF (tends to increase GFR)
Drop in glomerular capillary pressure (tends to decrease GFR)
Net effect: Small drop in GFR
When thinking of the kidney as a sprinkler how does constriction of the afferent/efferent arterioles effect the spray?
Describe the PGC, GFR, RBF changes in the following circumstances: Afferent constriction, efferent constriction, afferent and efferent constriction, no constriction.
What are the two mechanisms through which renal blood flow is autoregulated?
- The myogenic response
- The tubuloglomerular feedback
Between which arterial pressures does RBF and GFR remain fairly constant?
90 and 180 mm Hg
What is the mechanistic pathway of the myogenic mechanism?
Increase BP -> Ateriolar SM stretch -> Arteriolar contraction -> Increase resistance -> little change in RBF
The myogenic response mainly involves which type of arteriole?
Afferent
Describe the mechanistic flow of tubuloglomerular feedback.
Increased GFR -> increased tubular fluid flow rate -> increased Na and Cl delivery to macula densa -> increased vasoconstrictor signals (adenosine) -> Increase afferent arteriolar constriciton -> decrease RBF