Renal Flashcards
Highly selective proteinuria
Mostly low MW protein excretions; Minimal-change disease - defect in negatively charged molecules in GBM –> inability to repel albumin (also transferrin)
ACEi work how?
Decrease angioI->angioII, which blocks arteriolar vasoconstriction and aldosterone secretion. Ultimately lead to increased renin. B/c ACE breaks down bradykinin, increased bradykinin level.
Substances with no tubular absorption or secretion
Inulin and mannitol
Substances with net tubular secretion?
PAH (almost all secreted at PROXIMAL tube) and creatinine
Crescent formation pathogenesis?
Diagnostic for rapidly (wks-months) progresive glomerulonephritis. Dmg to BM lead to gaps where macrophages, T-cells, FIBRIN go into Bowman’s space. Fibrin deposition leads to parietal cell proliferation = crescent. Linear deposits of immunoglobulin.
Renal papillary necrosis associated with?
Sickle cell disease/trait. Analgesic nephropathy (e.g. phenacetin), DM, Acute pyelo or UT obstruction. Gray-white/yellow necrosis at distal renal pyramids. Coag infarct. Abrupt gross hematuria, colicky flank pain b/c of ureteral obstruction 2/2 sloughed papillae.
RPGN types?
Type 1 = anti-GBM. associated with Goodpasture syndrome. Immuno w/ IgG and C3 deposits (Type II HS). Type 2=IC-mediated 2/2 post-strep, SLE, IgA or Henoch-Schonlein….Type 3 = “pauci immune” w/ ANCA. Associated with Wegener’s.
Goodpasture’s
Anti-GBM (alpha-3 chain of collagen type IV). RPGN (crescents) and pulmonary hemorrhages.
Aldosterone
Synthesized and released by zone glomerulosa cells. Stimulated by angiotensin II and high serum K+. Promotes K+ secretion from principal cells and H+ secretion of intercalated cells of renal collecting tubules.
Drug that acts on proximal tubule
Acetazolamide - Carbonic anhydrase inhibitor. Drug blocks NaHCO3 reabsorption -> self-limited diuresis. Used for acute angle-closure glaucoma for dec. aqueous humor formation, metabolic alkalosis, pseudo tumor cerebra. Tox -hyperchloremic metabolic acidosis, parasethesias, NH3 fox, sulfa allergy
Drug that acts on descending Henle
Mannitol, an osmotic diuretic. Very permeable to water.
Drug that acts on thick ascending limb of Henle?
Loop diuretics (e.g. furosemide) Inhibits Na-K-2Cl symporters leading to increased Na, Cl-, and H2O excretion + Ca excretion.
Drug that acts on distal convoluted tubule
HCTZ. Impermeable to water and transports Na+ and Cl-.
Drugs that work on collecting duct?
K+ sparing diurects. Aldo receptor antagonists and amiloride (Na+ channel blocker)
RCC path
From renal tubular cells. Rounded or polygonal cells w/ abundant clear cytoplasm b/c had glycogen and lipids
Thiazide side effects
Decrease intravascular volume leads to aldo leads to excretion of K+ and H+ -> HypoK and metabolic ALKalosis. Hyponatremia. Hyperuricemia b/c of uric acid reabsorption in proximal tubules. HLD. Impaired carb tolerance. Hypercalcemia, hyperglycemia.
Role of mesonephros vs. metanephros?
Meta is SO VERY real. Mesonephros = interim kidney for 1st TM + ureteric bud –> ureter, pelvis, calyces, COLLECTING ducts by wk 10. Metanephros starts in wk 5. Metanephric mesenchyme interacts with ureteric bud to induce formation of glomerulus to distal convoluted tube. Last part of canalization is uretopelvic junction.
Pronephros?
Degenerates by wk 4.
Etios of Potter sequence
ARPKD, posterior urethral valves, b/l renal agenesis
Horseshoe kidney
Fusion of inferior poles. Then get trapped as ascend from pelvis by INFErior mesenteric artery. Increased risk of ureteropelvic junction obstruction, hydronephrosis, renal stones, Wilms. Associated with TURNER’s syndrome.
Multicystic dysplastic kidney
Etio is poor metanephric mesenchymal interaction with ureteric bud -> nonfunctional kidney of cysts and connective tissue. Often asymptomatic and unilateral due to hypertrophy of other kidney.
Interlobular artery vs. interlobar artery vs. arcuate artery?
Interlobar artery on either side of medullary pyramid. Arcuate arteries on cortical side. interlobular artery extend towards cortex.
Superficial cortical nephrons vs. juxtamedullary nephrons
Superficial cortical have glomeruli in outer corex with SHORT loops only descend to outer medulla. Juxtamedullary nephrons have glomeruli near corticomedullary border, larder glomeruli, LONG loops of Henle deep into papilla. Also have vasa recta, peritubular capillaries which follow loops
Where are juxtaglomerular cells compared to mesangial cells?
Juxtaglomerular cells located between afferent arteriole and macula dense (inward facing cells of distal renal tubule). Mesangial cells in the glomerulus.
Water under the bridge
Ureters under UTERINE artery and DUCTUS deferens.
What do I need to know about fluid compartments?
60-40-20 rule: 60% of body weight is water. (40% or 2/3 is ICF and 20% or 1/3 is ECF). 60-40-15-5 rule (5% or 1/4 of ECF is plasma volume and 15% or 3/4 of ECF is interstitial fluid).
How do you measure plasma volume and ECF volume?.
Radiolabeled albumin and inulin respectively.
Renal clearance
= volume of plasma cleared of a substance per unit time = substance clearance / plasma concentration = Urine conc. of X * urine flow rate / plasma concentration of X
What is glomerular filtration composed of?
Fenestrated capillary epithelium = size. Fused BM w/ HEPARAN sulfate = NEGATIVE charge barrier (lost in nephrotic syndrome -> albuminemia, hypoproteinemia, edema, hyperlipidemia). Epithelial layer of podocyte foot processes
GFR
Normally ~ 100 mL/min. Creatinine clearance slightly overestimates GFR b/c of slight secretion by renal TUBULES. GFR = [inulin]u x V / [inulin]p = Kf [ net hydrostatic pressure - net oncotic pressure)]
Renal PLASMA flow vs. renal BLOOD flow?
RBF > RPF b/c renal blood flow includes all the extra VOLUME of RBC’s
Renal plasma flow
Estimated w/ renal clearance of para-aminohippuric acid (PAH), which is filtered and secreted, and nearly ALL is EXCRETED. Therefore, eRPF = [PAH]u * V / [PAH]plasma. Estimates true RPF from Fick principle (with plasma conc. = renal artery - renal vein concentration, since no other organ extracts PAH and remain vein concentration = 0). eRPF underestimated by ~10% b/c renal vein conc. is NOT 0.
Renal blood flow
= RPF / (1 - Hct).
Filtered load?
mg/min = GFR (mL/min) x plasma concentration (mg/mL)
Filtration fraction (FF) =
GFR / RPF
Effects of arteriolar constriction on RPF, GFR, and FF?
Afferent constriction - dec. RPF, dec. GFR, - FF. Efferent constriction - dec. RPF, inc. GFR, inc. FF.
Glucose clearance?
At normal plasma lvls, glucose is completely reabsorbed at PROXIMAL tubule w/ Na+/glucose CO-transporter. At ~200 mg/dL glycosuria begins. At ~375 mg/dL, co-transporters are fully saturated. In pregnancy, reabsorption of aa’s and glucose in prox tubule down -> glycosuria and aminoaciduria
Amino acid clearance?
By proximal tubule with sodium-dependent transporters. Hartnup disease - Pellagra-like symptoms because these transporters can’t reabsorb leading to neutral aminaciduria and decreased aa absorption in gut. Tx = high-protein + nicotinic acid
Early PCT
Reabsorbs glucose, aa’s, phosphate/lactate/citrate with Na-X co-transporters. Reabsorbs 65-80% Na+ and 85% HCO3 with Na-H exchange and Carbonic anhydrase system. AT-II stimulates exchange –> reabsorbed Na+, HCO3, and water -> contraction alkalosis. PTH inhibits Na-Phos co-transport –> exertion of phosphate –> inc. Ca+ serum. Slightly NEGative lumen. Iso-osmotic water absorption.
Late PCT
High Cl-, no glucose, no aa, no HCO- enters. Na-H and Cl-FORMATE- exchanger AND paracellular absorption of NaCl via tight junctions –> Reabsorption of NaCl and water absorption. Iso-osmotic water absorption.
What drives reabsorption?
High oncotic pressure of peritubular capillary blood. The higher the GFR the higher the oncotic pressure, meaning that increased GFR leads to increased reabsorption (glomerulotubular balance). Balance upset by ECF volume changes (inc ECF -> decreased fractional reabsorption).
Thin descending and ascending loop of Henle
Descending loop is HIGHLY permeable to water and solutes while Ascending loop is NOT permeable to water. Medulla is hypertonic. So water moves out of thin descending, and solutes move INTO thin ascending —> concentrating/hypertonic urine
Thick ascending loop of Henle
ACTIVE reabsorption of Na+ (25%) in a LOAD-dependent fashion but NO water reabsorption. (This is why diuretics affecting proximal tube are mild b/c this part of loop makes up for it). Na-K-2Cl co-transporter driven by Na+ gradient. Reabsorption via Na-K ATPase (Na) and diffusion (K, Cl). Some K+ goes back to lumen = lumen-positive! Loop diuretics bind to Cl- portion. This is the DILUTING segment. Indirect paracellular reabsorption of Mg and Ca b/c of positive lumen.
Early distal convoluted tubule
Reabsorbs 5% of Na+ and Cl- via Na-Cl co-transporter (via Na+ gradient) in LOAD-dept fashion. Thiazide diuretics bind to Cl- site. IMPERMEABLE to water = “cortical dilutnig segment.” PTH increases Ca-Na exchange -> Inc Ca reabsorption. Used for HTN, CHF, idio hypercalciuria, nephrogenic DI, osteoporosis
Late distal convoluted tubule/Collecting Duct
Principal cells and alpha-intercalated cells. Principal - 3% Na+ reabsorption via channels (ENaC) under HORMONAL control. Aldosterone induces transcription of ENaC,Na-K ATPase, and enzymes of TCA cycle. Inhibited by K+-sparing diuretics (e.g. amiloride & triamterene block ENaC, spironolactone - which blocks aldo entering nucleus). Principals also secrete K+ and H+. ADH acts at V2 receptor to INSERT AQUAPORIN. Alpha-intercalated reabsorb K+ and excrete H+.
Fanconi syndrome
Frank is 1st. Reabsorption defect of PCT. Excretion of AAs, glucose, HCO3-, phosphate –> metabolic acidosis. etios - Wilson, ischemia, nephrotoxins/drugs
Renal Tubular Defects?
Fanconi, Barterr, Gitelman, Liddle. “F(r)ank and Bart Git Little Renal Tubules.”
Barterr syndrome
Bart is 2nd. Reabsorption defect of thick ascending Henle. AR affecting cotransporter -> hypokalemia, metabolic alkalosis, and hypercalciuria (stops paracellular)
Gitelman syndrome
Git is 3rd. Rebasorption defect of NaCl in DCT. AR and less severe than Barterr -> hypokalemia, metabolic alkalosis W/O hypercalciuria
Gitelman syndrome
Git is 3rd. Rebasorption defect of NaCl in DCT. AR and less severe than Barterr -> hypokalemia, metabolic alkalosis, hypocalciuria
TF/P?
Concentration of substrate in tubular fluid / conc. in plasma. TF/P = 1.0 is NO net reabsorption or secretion (e.g. Bowman’s space for freely filtered substance). TF/P < 1.0 is NET reabsorption relative to water. TF/P > 1.0 is NET secretion relative to water. (or less reabsorption compared to water).
The Many effects of AT-II
Hypothalamus - increases thirst and stimulate secretion of ADH -> inc. aquoporin insertion in principals cells. Vasculature - vasoconstriction via AT-II receptor. Adrenals - stimulates aldo release –> ENaC synthesis at principals cells of DCT/CT. Kidney - stimulates Na-H exchange at PCT -> Na+, HCO3, and water reabsorption. Constriction of efferent arteriole of glomerulus –> (inc GFR but dec RPF) increased FF. Limits baroreceptor thereby limiting reflex brady
Angiotensinogen, Renin, ACE are made?
Liver, Juxtoglomerular apparatus, Lung/kidney
What stimulates renin production?
Decreased Bp sensed by JG cells, decreased Na+ delivery (macula dense cells), or INC sympathetic tone (B1-receptors). All parts called the “Juxtoglomerular apparatus.”
ANP?
Released from atria b/c of INC volume. Relaxes vascular SMC via cGMP. Increased GFR, increased Na+ filtration w/o reabsorption –> NA+ LOSS and volume loss
EPO made where?
Interstitial cells in PERITUBULAR capillary bed in response to HYPOXIA
1,25-(OH)2 Vitamin D production?
Proximal tubule cells convert 25-OH D to 1,25 D with 1alpha-hydroxylase stimulated by PTH