1. Cells Extracellular Fluid Volume ~ 1/3 body water; Osmol 290 mOsm/Kg H 2 0 Na + 142 mM; K + 4 mM; H + 40 nM (pH 7.40) Intake: Na + ~ 5-200 mmoles/day K + ~ 50-300 “ H 2 0 ~ 0.5-3 L/day H + ~ 50-100 mEq/day Air water ~ 3000 mOsm/Kg H 2 0 urine

2. Kidney

3. Kidney Vasculature

4. Glomerulus

5. Nephron Circulation

6. Blood Flow in Resting Human RPF ~ 600 m/mi = 36L/h = 864L/day

7. Volume of Urine ~0.5-2 L/day GFR ~ 200 L/day

8. Glomerular Capillary Wall

9. Fractional Clearance Across Glomerular Capillary

10. Glomerular “Sieve”

11. Electrical Charge Effect on Fractional Clearance Across Glomerular Capillary

12. Forces Driving Filtration

13. Filtration & Reabsorption In Systemic Capillary

14. Forces Determining GFR Systemic capillary: F = Kf x [(Pc-Pi) - (  c-  I)] Glomerular capillary: GFR = Kf x [(Pgc-Pu) – (  gc-  u)] Because Pu is unregulated and believed to be constant and  U = 0, then GFR = Kf x (  P -  gc)

15. Permeability of Glomerular Capillary

16. Pressures Inside the Renal Circulation

17. Filtration Pressures in Glomerular Capillary

18. P UF 10 20 30 40  P = P GC -P U mm Hg Filtration Pressures in Glomerular Capillary  GC GFR=Kf x (  P -  GC) = Kf x P UF

19. P UF PP  GC PP PP ControlAngiotensin II ANP AAAEEE Distance Along Glomerular Capillary mm Hg 10 30 Factors Regulating P GC

20. Volume of Urine GFR ~ 50 - 200 L/d Urine, ~ 0.5 – 15 L/d

21. Nephron Capillaries

22. Filtration & Reabsorption In Systemic Capillary

23. P R = Kf (  C -  i ) – (P C - P i ) P R = Kf (  -  P) Starling’s Forces in Peritubular Capillary

24. mm Hg PRPR PRPR P UF Control Angiotensin II  GC  PP glomerular  P (P GC – P U ) peritubular glomerular PP  GC  Distance Along Capillary 10 30 PP Glomerular and Peritubular Starling Forces

25. Renin-Angiotensin System angiotensinogen angiotensin I converting enzyme angiotensin II renin vasoconstriction efferent constriction; net PT reabsorption increases PT reabs

26. Angiotensin II Direct Effects on Kidney Function 1 - constricts Efferent Arteriole: P GC and  GC ; doesnot change GFR but peritubular capillary  and, therefore, net Proximal Tubule sodiumreabsorption 2- directly Proximal Tubule Na + transport

27. Renin-Angiotensin System angiotensinogen angiotensin I converting enzyme angiotensin II renin vasoconstriction aldosterone; CD reabsorption efferent constriction; PT reabsorption

28. Aldo Aldosterone Effect on Na + and K + in the Collecting Duct

29. Fraction in urine (x 100) Fractional Na + in Urine along the Nephron Angio II Aldosterone

30. Measurement of GFR If a substance is freely filterable, then its rate of filtration is, Plasma [x] x GFR vol/time The rate of urinary excretion of any substance is, Urine [x] x Urine volume/time If all of x that is filtered appears in the final urine, then we have P[x] x GFR = U[x] x V and, GFR = U[x] x V / P[x]