Renal Physiology Overview Jeff Kaufhold, MD FACP.

Renal PhysiologyRenal PhysiologyOverviewOverview

Jeff Kaufhold, MD FACPJeff Kaufhold, MD FACP

Renal PhysiologyRenal Physiology

StructureStructureClearanceClearanceWater BalanceWater BalanceElectrolytes Electrolytes Acid-Base BalanceAcid-Base BalanceHormonal FunctionsHormonal Functions

Renal AnatomyRenal Anatomy

• Renal Artery and VeinRenal Artery and Vein• Cortex – filtering GlomeruliCortex – filtering Glomeruli• Medulla – Tubules, regulates water/ lytesMedulla – Tubules, regulates water/ lytes• UretersUreters• BladderBladder• Urethra and Sphincter controlUrethra and Sphincter control

Anatomy of Urinary TractAnatomy of Urinary Tract

Glomerular PhysiologyGlomerular Physiology

FiltrationFiltrationFiltration membraneFiltration membrane

Endothlial cell layerEndothlial cell layerBasement membraneBasement membraneEpithelial cell layerEpithelial cell layerElectrical charge – negativeElectrical charge – negative

Clearance = waste product removalClearance = waste product removalUltrafiltration = water removalUltrafiltration = water removal

Filtration MembraneFiltration Membrane

Glomerular Blood FlowGlomerular Blood Flow

Glomerular PhysiologyGlomerular PhysiologyBlood flow determinantsBlood flow determinants

Filtration

Systemic

EfferentAfferent

Effect of Angiotensin on Effect of Angiotensin on Glomerular Blood FlowGlomerular Blood Flow

Glomerular PhysiologyGlomerular PhysiologyBlood flow determinantsBlood flow determinants

Filtration

PG'sTGF

Local

EfferentAfferent

Glomerular PhysiologyGlomerular PhysiologyBlood flow determinantsBlood flow determinants

Filtration

Systemic

PG'sTGF

Local

EfferentAfferent

Glomerular filtrationGlomerular filtration

Glomerular PhysiologyGlomerular Physiology

Pathologic conditions:Pathologic conditions:Renal Artery StenosisRenal Artery StenosisHypertension / Medication effectsHypertension / Medication effectsMembrane problemsMembrane problems

Lead to blood in urine – hematuriaLead to blood in urine – hematuria -Loss of negative charge leads to protein in -Loss of negative charge leads to protein in

urine – proteinuriaurine – proteinuria -Diabetes, Glomerulonephritis-Diabetes, Glomerulonephritis

Blood Flow to TubulesBlood Flow to Tubules

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting ductreabsorption

Proximal TubuleProximal Tubule

Function:Function: ReabsorptionReabsorptionFeatures:Features: Brush border with ciliaBrush border with cilia Carbonic Anhydrase for Carbonic Anhydrase for

reclaiming Bicarbreclaiming Bicarb Filtration FractionFiltration FractionPathology: Renal tubular AcidosisPathology: Renal tubular Acidosis

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting ductreabsorption

blood

Tubule membrane

UltrafiltrateTubule lumen

Tubule membrane

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting duct

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting ductimpermeable to

H2Osolute

imperm. to

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting duct

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting duct

Ion Exchange Sodium for Potassium/Hydro

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting duct

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting duct

ADH +

ADH -

permeable to H2O

impermeable

Function of Nephron TubulesFunction of Nephron Tubules

Renal Tubule PhysiologyRenal Tubule PhysiologyOverviewOverview

Prox. tubule Distal Tubule

Loop of Henle

Collecting duct

ADH +

ADH -

permeable to H2O

impermeable

solute exchange

reabsorption

impermeable toH2Osolute

imperm. to

InterstitiumInterstitium

The tissue in between the tubulesThe tissue in between the tubulesFunction:Function: AmmoniagenesisAmmoniagenesis Countercurrent multiplierCountercurrent multiplierPathology:Pathology: RTA, Loss of concentrating ability, RTA, Loss of concentrating ability,

AINAIN

Countercurrent MultiplierCountercurrent Multiplier

Way to keep the concentrating ability of the Way to keep the concentrating ability of the kidney isolated from the rest of the bodykidney isolated from the rest of the body

Components:Components: Urine flow with sodium chloride pumpUrine flow with sodium chloride pump Blood flow from Vasa RectaBlood flow from Vasa RectaPathology:Pathology: Sickle Cell /Trait, bladder obstructionSickle Cell /Trait, bladder obstruction

Countercurrent MultiplierCountercurrent Multiplier

Countercurrent MultiplierCountercurrent Multiplier

Countercurrent MultiplierCountercurrent Multiplier

WARM

COLD

Renal PhysiologyRenal PhysiologyEndocrine FunctionsEndocrine Functions

Renin – control of BPRenin – control of BPErythropoietin – turns on bone marrow to Erythropoietin – turns on bone marrow to

make red blood cellsmake red blood cellsVitamin D activation – regulates bone Vitamin D activation – regulates bone

metabolism, Calcium, Phosphorus and metabolism, Calcium, Phosphorus and Parathyroid Gland.Parathyroid Gland.

Volume regulationVolume regulationActive SensorsActive Sensors

Renal Autonomic nervesRenal Autonomic nervesPassive systemPassive system

Like a system of lakes and spillwaysLike a system of lakes and spillways

Renal StructureRenal Structure

Artery

Vein

Ureter

C

M

P

Renal Structure

U

U 300

1200

Cortex

Medulla

Glomerulus

Vascularbundle

osmoticgradient

collecting tubule

Renal PhysiologyRenal PhysiologySensing of VolumeSensing of Volume

Effective Arterial Blood Volume (EABV)Effective Arterial Blood Volume (EABV) Pathology:Pathology: Congestive Heart FailureCongestive Heart Failure CirrhosisCirrhosis PregnancyPregnancy Nephrotic SyndromeNephrotic Syndrome AldosteronomaAldosteronoma

Pathologic StatesPathologic States CHFCHF Renal Artery StenosisRenal Artery Stenosis Low Blood FlowLow Blood Flow

Pathologic StatesPathologic States CirrhosisCirrhosis PregnancyPregnancy Nephrotic SyndromeNephrotic Syndrome

Leaky capillaries

Pathologic StatesPathologic States AldosteronomaAldosteronoma Tumor which Tumor which Produces too much Produces too much Aldosterone, causingAldosterone, causing Fluid retentionFluid retention

Pathologic StatesPathologic States Aldosteronoma Aldosteronoma

causescauses Fluid retentionFluid retention HypertensionHypertension Perfusion of outer Perfusion of outer

glomeruli sets upper glomeruli sets upper limit on how much limit on how much fluid can be retained.fluid can be retained.

Pathologic StatesPathologic States Removal of Removal of

Aldosteronoma Aldosteronoma causescauses

Diuresis until volume Diuresis until volume is normal again, andis normal again, and

Hypertension Hypertension improvesimproves

Why Kidney Patients willWhy Kidney Patients willCome to Physical TherapistsCome to Physical Therapists

Hip FracturesHip FracturesStrokesStrokesHeart attacks and heart surgeryHeart attacks and heart surgeryDeconditioningDeconditioningNeuropathyNeuropathy

Glomerular PhysiologyGlomerular Physiology

Afferent. ArtAfferent. Art AT II constrictAT II constrict

ACE-i dilateACE-i dilate

PG's NET dilatePG's NET dilate

TGF NET constrictTGF NET constrict

NSAID's constrictNSAID's constrict

Aminophylline dilateAminophylline dilate

Diltiazem dilateDiltiazem dilate

Filt PressFilt Press maintainedmaintained

reducedreduced

increaseincrease

parallelsparallels

reducereduce

increaseincrease

reducedreduced

Efferent Art.constrict

dilate

no effect

no effect

no effect

no effect

dilate