Renal Physiology Overview Jeff Kaufhold, MD FACP

Renal Physiology Structure Clearance Water Balance Electrolytes Acid-Base Balance Hormonal Functions

Renal Anatomy Renal Artery and Vein Cortex – filtering Glomeruli Medulla – Tubules, regulates water/ lytes Ureters Bladder Urethra and Sphincter control

Anatomy of Urinary Tract

Glomerular Physiology Filtration Filtration membrane Endothlial cell layer Basement membrane Epithelial cell layer Electrical charge – negative Clearance = waste product removal Ultrafiltration = water removal

Filtration Membrane

Glomerular Blood Flow

Glomerular Physiology Blood flow determinants Systemic Efferent Afferent Filtration

Effect of Angiotensin on Glomerular Blood Flow

Glomerular Physiology Blood flow determinants Efferent Afferent PG's Local TGF Filtration

Glomerular Physiology Blood flow determinants Systemic Efferent Afferent PG's Local TGF Filtration

Glomerular filtration

Glomerular Physiology Pathologic conditions: Renal Artery Stenosis Hypertension / Medication effects Membrane problems Lead to blood in urine – hematuria -Loss of negative charge leads to protein in urine – proteinuria -Diabetes, Glomerulonephritis

Blood Flow to Tubules

Renal Tubule Physiology Overview Prox. tubule Distal Tubule reabsorption Collecting duct Loop of Henle

Proximal Tubule Function: Reabsorption Features: Brush border with cilia Carbonic Anhydrase for reclaiming Bicarb Filtration Fraction Pathology: Renal tubular Acidosis

Renal Tubule Physiology Overview Prox. tubule Distal Tubule blood Tubule membrane reabsorption Collecting duct Ultrafiltrate Tubule lumen Loop of Henle Tubule membrane

Renal Tubule Physiology Overview Prox. tubule Distal Tubule Collecting duct Loop of Henle

Renal Tubule Physiology Overview Prox. tubule Distal Tubule Collecting duct impermeable to imperm. to H2O solute Loop of Henle

Renal Tubule Physiology Overview Prox. tubule Distal Tubule Collecting duct Loop of Henle

Renal Tubule Physiology Overview Ion Exchange Sodium for Potassium/Hydro Prox. tubule Distal Tubule Collecting duct Loop of Henle

Renal Tubule Physiology Overview Prox. tubule Distal Tubule Collecting duct Loop of Henle

Renal Tubule Physiology Overview Prox. tubule Distal Tubule Collecting duct ADH + permeable to H2O Loop of Henle ADH - impermeable

Function of Nephron Tubules

Renal Tubule Physiology Overview Prox. tubule Distal Tubule solute exchange reabsorption Collecting duct impermeable to imperm. to H2O solute ADH + permeable to H2O Loop of Henle ADH - impermeable

Interstitium The tissue in between the tubules Function: Ammoniagenesis Countercurrent multiplier Pathology: RTA, Loss of concentrating ability, AIN

Countercurrent Multiplier Way to keep the concentrating ability of the kidney isolated from the rest of the body Components: Urine flow with sodium chloride pump Blood flow from Vasa Recta Pathology: Sickle Cell /Trait, bladder obstruction

Countercurrent Multiplier

Countercurrent Multiplier

Countercurrent Multiplier WARM COLD

Renal Physiology Endocrine Functions Renin – control of BP Erythropoietin – turns on bone marrow to make red blood cells Vitamin D activation – regulates bone metabolism, Calcium, Phosphorus and Parathyroid Gland.

Volume regulation Active Sensors Passive system Renal Autonomic nerves Like a system of lakes and spillways

Renal Structure C Artery P Vein M Ureter

Renal Structure U Cortex U osmotic Vascular 300 gradient bundle Medulla collecting tubule Glomerulus 1200 U

Renal Physiology Sensing of Volume Effective Arterial Blood Volume (EABV) Pathology: Congestive Heart Failure Cirrhosis Pregnancy Nephrotic Syndrome Aldosteronoma

Pathologic States CHF Renal Artery Stenosis Low Blood Flow

Pathologic States Cirrhosis Pregnancy Nephrotic Syndrome Leaky capillaries

Pathologic States Aldosteronoma Tumor which Produces too much Aldosterone, causing Fluid retention

Pathologic States Aldosteronoma causes Fluid retention Hypertension Perfusion of outer glomeruli sets upper limit on how much fluid can be retained.

Pathologic States Removal of Aldosteronoma causes Diuresis until volume is normal again, and Hypertension improves

Why Kidney Patients will Come to Physical Therapists Hip Fractures Strokes Heart attacks and heart surgery Deconditioning Neuropathy

Glomerular Physiology Afferent. Art AT II constrict ACE-i dilate PG's NET dilate TGF NET constrict NSAID's constrict Aminophylline dilate Diltiazem dilate Filt Press maintained reduced increase parallels reduce Efferent Art. constrict dilate no effect