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RBF = 1300 ml/min. GFR = 125 ml/min V = 1 ml/min. Renal Resistance Vessels and the Intrarenal Hydraulic Pressure Profile. Glomerular Hemodyamics. RBF. P GC. Normal. Afferent Dilation. Afferent Constriction. Efferent Dilation. Efferent Constriction. Autoregulation.
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RBF = 1300 ml/min GFR = 125 ml/min V = 1 ml/min
Renal Resistance Vessels and the Intrarenal Hydraulic Pressure Profile
Glomerular Hemodyamics RBF PGC Normal Afferent Dilation Afferent Constriction Efferent Dilation Efferent Constriction
Glomerular Permselectivity • Shape • Size • Charge
Glomerular Permselectivity Filtrate to plasma Concentration Ratio
Glomerular Filtration • As described by Starling: • GFR = Kf {(PGC - PBC) - PGC} Kf = “Ultrafiltration Coefficient” PGC = Glomerular capillary hydraulic pressure PBC = Bowman’s capsule pressure PGC = Glomerular capillary oncotic pressure
Filtration Equilibrium However, Driving forces along the axis of the glomerular capillaries are NOT constant.
Filtration Equilibrium 1.Between afferent and efferent arteriole, plasma protein concentration and PGC rise. 2.Eventually NET driving forces favoring filtration are eliminated so that (PGC - PBC) = PGC.
Glomerulus and Juxtaglomerular Apparatus • Regulatory Elements • Renal Arterioles / PGC • Macula Densa / TGF • Renin Secretion
Tubulo-Glomerular Feedback Distal Flow AfferentResistance - PGC GFR
Tubulo-Glomerular Feedback Afferent Resistance Distal Flow + PGC GFR