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30 Cards in this Set
- Front
- Back
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What is normal GFr
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120 ml/min or 180 l/day.
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Where is RBF directed?
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More than 90% of renal blood flow
(RBF) is directed to the renal cortex and courses through glomeruli |
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Ultrafiltrate
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Water and electrolytes
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PGC
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glomerular capillary hydrostatic pressure
Force promoting filtration! |
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Pi-bs
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Colloid Osmotic pressure in the bowmans capsule
Favors filtration |
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Pt
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Proximal tubule (bow mans space) hydrostatic pressure
Force opposing filtration |
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Pi-Gc
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colloid osmotic pressure in glomerular capillaries
Force opposing filtration |
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What two factors mostly contribute to GFR (sngfr)w
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balance between the hydrostatic pressure gradient, P (the predominant force driving filtration)
and glomerular capillary colloid osmotic pressure, Pi-GC. |
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Capillary surface area under control of
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Mesengial cells
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Pressure in the glomerular capillary is how much of the systemic pressure
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1/2 butnhigher than peripheral blood capillaries
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Step down in pressure
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change in the afferent arteriole pressure and the capillary pressure (approx. half)
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Afferent arteriole affected by:
Efferent arteriole affected by: |
prostaglandins, NO
Angiotensin-2 |
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NSAIDS do
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impair prostaglandin synthesis so you block afferent vasodilation and prevent autoregulation
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ACE-Inhibitors do
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block constriction of efferent arterioles and prevent autoregulation
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what charge does the basement membrane have
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negative
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is clearance better for a positive or negative ion
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positive
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filtered load = urinary excretion for which substance
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inulin
filtered load: Cx X Px urinary excretion: Ux X V |
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Inulin
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freely filtered but not reabsorbed
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PAH
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freely filtered and secreted
(no PAH in renal venous blood) |
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RPF=
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Clearance of PAH
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RBF=
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RPF/ 1-Hct
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GFR=
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120 ml/min
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RPF=
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600 ml/min
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Filtration Fraction
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20%, 20% of renal blood flow is filtered
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In heart failure what happens to GFR and RBF
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GFR usually stays the same, RBF goes down so FF goes up
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increase in colloid osmotic pressure (pi-gc) due to...
and leads to... |
high FF
increased reabsorption of sodium and water from the tubule |
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Blocks to anionic charge
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endothelial cells
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True RPF is 10% higher than
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effective RPF (Cpah estimates effective RPF)
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when Cin > Cx there is a net
when Cx> Cin there is a net |
reabsoprtion
secretion |
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RBF
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RPF / 1-Hct
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