Renal Structure and Function Sodium Transport

Transcription

1 Renal Structure and Function Sodium Transport UTSouthwestern STARS Program Orson W. Moe, M.D. Department of Internal Medicine Division of Nephrology

2 organism world Composition Quantity Maintain constancy

3 Afferent Sensor Physiologic parameter Efferent Effector Disease

4 Renal Function Good stuff Bad stuff Endocrine hormone Metabolic substrate Excretion Endocrine Metabolism

5 Gross anatomy

6 Medulla Outer Outer stripe Inner stripe Inner Medulla (Pyramids) Papilla Capsule Medullary rays Cortex Renal pelvis Ureter Major calyx Column of Bertin Minor calyx

7 Renal Vasculature Afferent arteriole Arcuate Cortical ascending Renal artery Segmental branches Main branch Interlobar Interlobar Arcuate

8 Cortical ascending Afferent arteriole Arcuate Efferent arteriole

9 Renal Circulation Little or no anastomoses Highest blood flow per gram tissue Multiple capillaries in tandem Functional arteriovenous shunts

10 Renal Circulation Little or no anastomoses Highest flow per gram tissue Multiple capillaries in tandem Functional AV shunts

11 Renal Circulation Little or no anastomoses Highest flow per gram tissue Multiple capillaries in tandem Functional AV shunts 25-30% Cardiac output <2% Body mass Renal venous po 2 Highest (60-70 mm Hg) Renal A-VO 2 difference Lowest (10-15%)

12 Glomerular capillary Peritubular capillary Renal Circulation Little or no anastomoses Highest flow per gram tissue Multiple capillaries in tandem Functional AV shunts

13 Functional AV shunts Renal Circulation Little or no anastomoses Highest flow per gram tissue Multiple capillaries in tandem Functional AV shunts Cortical ascending Afferent arteriole Glomerular capillary Efferent arteriole Peritubular capillary Vasa recta

14 Excretion Ultrafiltration Secretion Reabsorption

15 Nephron Secretory Filtration-Reabsorption

16 Nephron Secretory Dump Filtration-Reabsorption

17 Nephron Secretory Dump Filtration-Reabsorption

18 300 marbles Remove 294

19 300 marbles Remove 294

20 300 marbles Remove 294 Put 6 back

21 What does that mean? 5% error 1 L/day 1 L/day 0.95 L/day 0.95 L/day Error = 50 ml 170 L/day 5% error 1 L/day 10 L/day Error = 9L 169 L/day 160 L/day

22 Filtration-Secretion Fractional excretion Amount excreted Amount filtered Amount filtered Amount excreted > 1 Filtration Amount filtered Amount excreted = 1 Filtration-Reabsorption Amount filtered Amount excreted < 1

23 Walk the nephron

24 Overview Distal convoluted tubule Cortical collecting tubule Afferent arteriole Cortical nephron Glomerulus Juxtamedullary nephron Proximal convoluted tubule Efferent arteriole Proximal straight tubule Proximal convoluted tubule Cortex Proximal straight tubule Descending thin limb Thick ascending limb Medullary collecting tubule Outer Medulla Loop of Henle Thin ascending limb Inner Medulla

25 The Glomerulus Form an ultrafiltrate

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34 Afferent arteriole Parietal epithelium Visceral epithelium Tubule Bowman s space Urinary lumen Efferent arteriole GBM Mesangium

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37 Tubule lumen Visceral epithelial cells (podocytes) Bowman's space Bowman's capsule Parietal epithelial cells Visceral epithelial cell (foot processes) Capillary basement membrane Capillary endothelial cells Nerve fibers Afferent arteriole Juxtaglomerular granular cells Macula densa cells Glomerular capillary lumen Mesangial extracellular matrix Mesangial cells Smooth muscle cells Efferent arteriole Distal end of the thick ascending limb Extraglomerular mesangium

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39 Bowman space Podocyte Capillary

40 Foot process Podocyte Endothelial cell Mesangial matrix Mesangial cell

41 Podocyte Foot process Endothelium

42 Blood cells Large proteins Small proteins Electrolytes Water Basement membrane Endothelium Podocyte foot process

43 Transition to tubule

44 Renal Tubules Modify the ultrafiltrate into final urine

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46 Overview Distal convoluted tubule Cortical collecting tubule Afferent arteriole Cortical nephron Glomerulus Juxtamedullary nephron Proximal convoluted tubule Efferent arteriole Proximal straight tubule Proximal convoluted tubule Cortex Proximal straight tubule Descending thin limb Thick ascending limb Medullary collecting tubule Outer Medulla Loop of Henle Thin ascending limb Inner Medulla

47 Proximal straight tubule Proximal convoluted tubule Distal tubule Intercalated Principal cell cell Cortical collecting tubule Thick ascending limb Inner medullary collecting tubule Descending thin limb Ascending thin limb

48 Transport Transcellular Paracellular Protrusions Brush border Features of tubular epithelia Tight junctions Intercellular space Infoldings Interdigitation Polarized Apical Basolateral Amplification of surface area Brush border Infolding Interdigitation

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50 Currency for Solute Transport High energy metabolic substrates ATP Electrochemical gradients

51 Glutamine ATP 3Na + Urine 2K + Low [Na + ] -ve voltage Interstitium/ Plasma

52 ATPase Na + Cotransporter Countertransporter H + Channel K + ATP Na + Glucose Na + Na + Coupled Transporters H + OH - Paracellular Transport Proteins Ca 2+ Na + Cl -

53 NaCl

54 Yanomami Indians Daily ingestion & excretion Yanomani K meq/day Na + <10 meq/day Dallasite 40 meq/day 200 meq/day

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56 NaCl 100% 50-60% 7-10% 2-5% Cortex Medulla 30% 1-2%

57 Proximal nephron Distal nephron Transcellular pathway Interstitium/Capillary Paracellular pathway Urinary Lumen Low gradient High capacity High gradient Low capacity

58 Capillary Cl - 3Na + 3Na + 3Na + ~ ~ ~ Cl - 3Na + ~ 2K 2K + 2K ~2K K + Na + Na + X Na + 2Cl - Na + Cl - Na + Proximal X Lumen Distal Low gradient High capacity High gradient Low capacity

59 Proximal tubule

60 Thick ascending limb

61 Distal convoluted tubule

62 Collecting tubule

63 Afferent Sensor Physiologic parameter Efferent Effector Disease Ultrafiltrate Urine