Renal Anatomy, Filtration and Clearance
Core facts on nephron structure, glomerular Starling forces, GFR and clearance calculations.
Keyboard Shortcuts
💡 Pro tip: Use keyboard shortcuts for faster studying!
Study Smart Tips for Renal Anatomy, Filtration and Clearance
Master these concepts using proven study techniques that actually work:
Active Recall
Test yourself before flipping each card to strengthen memory retention
Spaced Repetition
Review difficult cards more frequently than easy ones
Multiple Sessions
Break study time into shorter, focused sessions
Explain Aloud
Verbalize answers to reinforce understanding
Questions Covered in This Set
10 cards to master
What are the three layers of the glomerular filtration barrier?
Fenestrated capillary endothelium (blocks cells), glomerular basement membrane (negatively charged heparan sulfate, blocks anionic proteins), and podocyte foot processes with slit diaphragms (nephrin, podocin).
Write the Starling equation for GFR and typical values.
GFR = Kf[(P_GC − P_BS) − (π_GC − π_BS)]; P_GC ≈ 55, P_BS ≈ 15, π_GC ≈ 30, π_BS ≈ 0 → net ≈ 10 mmHg outward, giving ~180 L/day of filtrate.
What is the clearance equation and its units?
C_X = (U_X × V̇)/P_X, where U_X is urine concentration, V̇ is urine flow rate (mL/min), P_X is plasma concentration. Units are mL/min.
Which substance's clearance equals GFR, and which approximates it clinically?
Inulin (freely filtered, not reabsorbed or secreted) is the gold standard; creatinine approximates GFR but slightly overestimates it due to tubular secretion.
Why does PAH clearance estimate renal plasma flow?
PAH is filtered and almost completely secreted, so nearly all plasma reaching the tubules is cleared of it; it measures effective RPF (~90% of true RPF because some blood bypasses tubules).
Effect of efferent arteriole constriction (e.g., angiotensin II) on GFR and RPF?
Blood is dammed in the glomerulus: P_GC ↑ → GFR ↑ while RPF ↓, so filtration fraction ↑. Extreme constriction eventually drops GFR too.
Effect of afferent arteriole constriction?
Less blood entering → P_GC ↓ → both RPF and GFR fall.
Why does an ACE inhibitor acutely drop GFR?
It removes angiotensin II–mediated efferent constriction, dilating the efferent arteriole and lowering P_GC — dangerous in bilateral renal artery stenosis where GFR depends on Ang II.
How does a ureteral stone change GFR?
It raises Bowman's space hydrostatic pressure (P_BS), opposing filtration, so GFR falls.
Why does minimal change disease cause selective albuminuria?
Loss of the negative charge barrier (heparan sulfate/podocyte charge) lets anionic albumin (69 kDa) leak, while structural podocyte loss (FSGS) leaks proteins non-selectively.
