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Home , Distal convoluted tubule, Efferent arteriole, Glomerulus (kidney), Loop of Henle, Nephron, Proximal tubule

Renal Structure and Function Transport

UTSouthwestern STARS Program

Orson W. Moe, M.D. Department of Internal Medicine Division of organism world

Composition Quantity

Maintain constancy Disease

Physiologic Afferent parameter Efferent Sensor Effector Renal Function Good stuff Bad stuff Endocrine Metabolic substrate

Excretion

Endocrine

Metabolism Gross Medulla (Pyramids) Medulla Outer Papilla Outer stripe Inner stripe Capsule Inner Medullary rays

Cortex

Major calyx Renal Column of Bertin Minor calyx Renal Vasculature

Afferent

Cortical ascending Arcuate

Renal artery Segmental branches

Main branch Interlobar

Interlobar

Arcuate Cortical ascending

Afferent arteriole

Arcuate

Efferent arteriole Little or no anastomoses Highest flow per gram tissue Multiple in tandem Functional arteriovenous shunts Renal Circulation Little or no anastomoses Highest flow per gram tissue Multiple capillaries in tandem Functional AV shunts 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 pO2 Highest (60-70 mm Hg) Renal A-VO2 difference Lowest (10-15%) Glomerular Renal Circulation Little or no anastomoses Highest flow per gram tissue Peritubular Multiple capillaries in tandem capillary Functional AV shunts Renal Circulation Little or no anastomoses Highest flow per gram tissue Multiple capillaries in tandem Functional AV shunts

Glomerular Peritubular capillary capillary Afferent Cortical ascending arteriole

Vasa recta

Functional AV shunts

Ultrafiltration

Secretion

Reabsorption

Secretory

Filtration- Nephron

Secretory Dump

Filtration-Reabsorption Nephron

Secretory Dump

Filtration-Reabsorption 300 marbles Remove 294 300 marbles Remove 294 300 marbles Remove 294

Put 6 back What does that mean?

5% error

1 L/day 1 L/day Error = 50 ml 0.95 L/day 0.95 L/day

5% error 170 L/day 1 L/day Error = 9L 10 L/day

169 L/day 160 L/day Amount excreted Fractional excretion Amount filtered Filtration-

Amount Amount filtered > 1 excreted

Filtration

Amount Amount = 1 filtered excreted

Filtration-Reabsorption

Amount Amount filtered excreted < 1 Walk the nephron Overview

Afferent arteriole Distal convoluted Cortical nephron Cortical collecting tubule

Juxtamedullary nephron Proximal convoluted Proximal Efferent tubule convoluted arteriole tubule Proximal straight tubule Cortex

Proximal straight tubule Outer Thick ascending limb Medulla Descending thin limb

Medullary collecting tubule

Thin Inner ascending Medulla limb The Glomerulus

Form an ultrafiltrate

Afferent arteriole Parietal

Visceral epithelium

Tubule

Bowman’s space Urinary

Efferent arteriole GBM

Mesangium

Visceral Tubule lumen epithelial cells Bowman's space () Bowman's capsule

Parietal epithelial cells

Visceral epithelial cell (foot processes) Afferent Nerve arteriole Capillary fibers basement Juxtaglomerular granular membrane cells

Capillary Macula endothelial densa cells cells

Glomerular capillary Distal end lumen of the thick Smooth ascending limb Mesangial muscle cells extracellular Mesangial Efferent arteriole matrix cells

Extraglomerular mesangium

Bowman space

Podocyte

Capillary Foot process

Podocyte

Endothelial cell

Mesangial matrix

Mesangial cell Podocyte

Foot process

Endothelium Blood cells Large proteins Small proteins Electrolytes

Endothelium

Podocyte foot process Transition to tubule Renal

Modify the ultrafiltrate into final

Overview

Afferent arteriole Cortical nephron Glomerulus Cortical collecting tubule

Juxtamedullary nephron Proximal convoluted Proximal Efferent tubule convoluted arteriole tubule Proximal straight tubule Cortex

Proximal straight tubule Outer Thick ascending limb Medulla Descending thin limb

Medullary collecting tubule

Thin Loop of Henle Inner ascending Medulla limb Proximal Distal convoluted tubule tubule

Intercalated Principal cell Proximal cell Cortical straight collecting tubule tubule

Thick Inner ascending medullary limb collecting tubule

Descending Ascending thin limb thin limb Brush border Protrusions Features of tubular epithelia

Tight junctions

Intercellular space

Infoldings Interdigitation

Polarized Apical Basolateral Amplification of surface area Brush border Infolding Interdigitation

Transport Transcellular Paracellular

Currency for Solute Transport

High energy metabolic substrates

ATP

Electrochemical gradients

ATP 3Na+

2K+

Low [Na+] Urine -ve voltage Interstitium/ Plasma ATPase Cotransporter Countertransporter Channel Na+ H+

+ + + Na+ K ATP Na Na

Paracellular Transport Proteins Coupled Transporters Ca2+ H+ OH-

Na+ Cl- NaCl Yanomami Indians

Daily ingestion & excretion

Yanomani Dallasite K+ 400-500 mEq/day 40 mEq/day Na+ <10 mEq/day 200 mEq/day

NaCl

100%

50-60% 7-10% 2-5%

Cortex 30% Medulla

1-2% Proximal Distal nephron nephron

Transcellular Interstitium/Capillary pathway

Paracellular pathway Urinary Lumen

Low gradient High gradient High capacity Low capacity Capillary

3Na+ 3Na+ 3Na+ 3Na+ Cl- Cl- ~ ~ ~ ~ 2K+ 2K+ 2K+ 2K+

+ K + Na+ Na+ X Na+ 2Cl- Na+ Cl- Na

X Lumen Proximal Distal

Low gradient High gradient High capacity Low capacity Thick ascending limb Distal convoluted tubule Collecting tubule Disease

Physiologic Afferent parameter Efferent Sensor Effector

Ultrafiltrate

Urine