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Renal Structure and FunctionSodium Transport
Orson W. Moe, M.D.Department of Internal Medicine
Division of Nephrology
UTSouthwestern STARS Program
organism world
Maintain constancy
CompositionQuantity
Afferent Sensor
Efferent Effector
Physiologic parameter
Disease
Excretion
Endocrine
Metabolism
Renal FunctionGood stuffBad stuffEndocrine hormoneMetabolic substrate
Gross anatomy
Medulla (Pyramids)
Capsule
Medullary rays
Cortex
Major calyx
Minor calyx
Renal pelvis
Ureter
Column of Bertin
MedullaOuter
Outer stripeInner stripe
Inner
Papilla
Afferent arteriole
Cortical ascending
Arcuate
Interlobar
Renal arterySegmental branches
Main branch
Interlobar
Arcuate
Renal Vasculature
Arcuate
Cortical ascending
Afferent arteriole
Efferent arteriole
Renal CirculationLittle or no anastomosesHighest blood flow per gram tissueMultiple capillaries in tandem Functional arteriovenous shunts
Renal CirculationLittle or no anastomosesHighest flow per gram tissueMultiple capillaries in tandemFunctional AV shunts
Renal CirculationLittle or no anastomosesHighest flow per gram tissueMultiple capillaries in tandemFunctional AV shunts
<2% Body mass
25-30% Cardiac output
Renal venous pO2 Highest (60-70 mm Hg)Renal A-VO2 difference Lowest (10-15%)
Renal CirculationLittle or no anastomosesHighest flow per gram tissueMultiple capillaries in tandemFunctional AV shunts
Glomerular capillary
Peritubular capillary
Renal CirculationLittle or no anastomosesHighest flow per gram tissueMultiple capillaries in tandemFunctional AV shunts
Cortical ascending
Afferent arteriole
Glomerular capillary
Efferent arteriole
Peritubular capillary
Vasa recta
Functional AV shunts
Excretion
Secretion
Ultrafiltration
Reabsorption
Nephron
Secretory
Filtration-Reabsorption
Secretory
Filtration-Reabsorption
Nephron
Dump
Secretory
Filtration-Reabsorption
Nephron
Dump
300 marbles
Remove 294
300 marbles
Remove 294
300 marbles
Remove 294
Put 6 back
170 L/day
169 L/day
1 L/day
1 L/day1 L/day
0.95 L/day 0.95 L/day
160 L/day
10 L/day
Error = 50 ml
Error = 9L
What does that mean?
5% error
5% error
Filtration-Secretion
Filtration-Reabsorption
Filtration
Fractional excretion
Amount excreted
Amount filtered
Amount filtered
Amount filtered
Amount excreted
Amount excreted
Amount excretedAmount filtered
> 1
= 1
< 1
Walk the nephron
Juxtamedullary nephron
Medullary collecting tubule
Cortical collecting tubule
Distal convoluted tubule
Thick ascending limb
Thinascendinglimb
Loop of Henle
Descending thin limb
Proximal straight tubule
Proximal straight tubule
Efferentarteriole
Glomerulus
Afferent arteriole
Proximalconvoluted
tubule
Proximalconvolutedtubule
InnerMedulla
Cortex
OuterMedulla
Cortical nephron
Overview
The Glomerulus
Form an ultrafiltrate
Parietal epithelium
Tubule
GBM
Afferent arteriole
Efferent arteriole
Mesangium
Visceral epithelium
Bowman’s space Urinary lumen
Tubule lumenVisceral
epithelial cells(podocytes)
Bowman's space
Bowman's capsule
Parietal epithelial cells
Nervefibers
Afferentarteriole
Juxtaglomerulargranular
cells
Maculadensacells
Efferent arteriole
Smoothmuscle cells
Mesangialcells
Mesangialextracellular
matrix
Glomerularcapillarylumen
Capillaryendothelial
cells
Capillarybasementmembrane
Visceralepithelial cell
(foot processes)
Distal endof the thick
ascending limb
Extraglomerular mesangium
Podocyte
Capillary
Bowman space
Podocyte
Mesangial cell
Mesangial matrix
Foot process
Endothelial cell
Podocyte
Foot process
Endothelium
Endothelium
Podocyte foot process
Basement membrane
Blood cellsLarge proteinsSmall proteinsElectrolytesWater
Small proteinsElectrolytesWater
Transition to tubule
Renal Tubules
Modify the ultrafiltrate into final urine
Juxtamedullary nephron
Medullary collecting tubule
Cortical collecting tubule
Distal convoluted tubule
Thick ascending limb
Thinascendinglimb
Loop of Henle
Descending thin limb
Proximal straight tubule
Proximal straight tubule
Efferentarteriole
Glomerulus
Afferent arteriole
Proximalconvoluted
tubule
Proximalconvolutedtubule
InnerMedulla
Cortex
OuterMedulla
Cortical nephron
Overview
Proximalconvoluted
tubule
Proximalstraighttubule
Thickascending
limb
Descendingthin limb
Ascendingthin limb
Innermedullarycollecting
tubule
Corticalcollecting
tubule
Distaltubule
Principalcell
Intercalatedcell
PolarizedApicalBasolateral
Amplification of surface areaBrush borderInfoldingInterdigitation
TransportTranscellularParacellular
Infoldings Interdigitation
ProtrusionsBrush border
Tight junctions
Intercellular space
Features of tubular epithelia
Currency for Solute Transport
High energy metabolic substrates
ATP
Electrochemical gradients
ATP
Urine Interstitium/ Plasma
Glutamine
2K+
Low [Na+]-ve voltage
3Na+
Coupled Transporters Paracellular Transport Proteins
ATP
ATPaseNa+
K+
Cotransporter
Na+ Glucose
Na+
OH-H+
Cl-
Ca2+
Channel
Na+
Countertransporter
Na+
H+
NaCl
Yanomami Indians
Daily ingestion & excretion
Yanomani DallasiteK+ 400-500 mEq/day 40 mEq/dayNa+ <10 mEq/day 200 mEq/day
Cortex
Medulla
50-60% 7-10%
2-5%
30%
100%
NaCl
1-2%
Proximalnephron
Distalnephron
Urinary Lumen
Interstitium/CapillaryTranscellularpathway
Paracellularpathway
High capacity Low capacity
Low gradient High gradient
~
3Na+
~ ~~
Lumen
High capacity Low capacity
Low gradient High gradient
Capillary
Cl-Cl-
Proximal Distal
3Na+
~
2K+
~
3Na+
2K+2K+
~
2K+
~
3Na+
X
XNa+ Na+ Na+Na+ Cl-Na+ 2Cl-K+
Proximal tubule
Thick ascending limb
Distal convoluted tubule
Collecting tubule
Afferent Sensor
Efferent Effector
Physiologic parameter
Disease
Ultrafiltrate
Urine
