Introduction Filtration fraction (FF) represents the ratio between glomerular filtration rate (GFR) and renal plasma flow (RPF) this in turn represents which fraction of RPF becomes filtered via the glomerular capillaries the normal filtration fraction is ~20% and thus implies that 80% of the RPF is not filtered the unfiltered RPF will then be part of the peritubular capillary blood flow after entering the efferent arteriole Filtration fraction (FF) = GFR / RPF Filtered load = GFR x plasma concentration Renal plasma flow (RPF) can be determined by using clearance of para-aminohippuric acid (PAH) RPF = [U(PAH) x V] / [RA(PAH) - RV (PAH)] U(PAH) = urine concentration of PAH (mg/mL) V = urine flow rate (mL/min) RA(PAH) = renal artery concentration of PAH (mg/mL) RV(PAH) = renal vein concentration of PAH (mg/mL) determining the RPF will allow you to determine the renal blood flow (RBF) RBF = RPF / (1 - hematocrit) Changes in Starling Force and Its Effect On RPF, GFR, and FF Condition RPF GFR FF (GFR/RPF) Afferent arteriole constriction ↓ ↓ Unchanged Efferent arteriole constriction ↓ ↑ ↑ ↑ plasma protein concentration Unchanged ↓ ↓ ↓ plasma protein concentration Unchanged ↑ ↑ Ureter constriction Unchanged ↓ ↓
QUESTIONS 1 of 5 1 2 3 4 5 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.RL.12.69) A healthy 30-year-old female has a measured creatinine clearance of 100 mL/min. She has a filtration fraction (FF) of 25%. Serum analysis reveals a creatinine level of 0.9 mg/dL and an elevated hematocrit of 0.6. Which of the following is the best estimate of this patient’s renal blood flow? QID: 101023 Type & Select Correct Answer 1 400 mL/min 21% (29/138) 2 600 mL/min 9% (13/138) 3 800 mL/min 12% (16/138) 4 1.0 L/min 45% (62/138) 5 1.2 L/min 8% (11/138) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.RL.12.20) Activation of the renin-angiotensin-aldosterone system yields a significant physiological effect on renal blood flow and filtration. Which of the following is most likely to occur in response to increased levels of Angiotensin-II? QID: 100974 Type & Select Correct Answer 1 Increased renal plasma flow, decreased filtration fraction 5% (4/86) 2 Increased renal plasma flow, increased filtration fraction 22% (19/86) 3 Decreased renal plasma flow, decreased filtration fraction 5% (4/86) 4 Decreased renal plasma flow, increased filtration fraction 65% (56/86) 5 Decreased renal plasma flow, increased glomerular capillary oncotic pressure 1% (1/86) M 1 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic