renal

Question 1

embryology

Answer 1

• Pronephros - week 4 –> degenerates
• Mesonephros– functions as interim kidney for 1st trimester then contributes to male genital system
• Metanephros – permanent
  
  • ureteric bud gives rise to collecting system (ureters, pelvises, calyces and CDs)
  • metanephric mesenchyme interacts with ureteric bud –> gives rise to nephron (glomerulus, Bowman’s space, prox tubule, LH + DCT)
• ureteropelvic junction is last to canalize – most common site of obstruction (hydronephrosis) in infant

Question 2

1. fluid compartments
2. Renal clearance
3. GFR
4. RPF

Answer 2

1. total body water = 60% total body mass –> 2/3 intracellular; 1/3 extracellular –> 3/4 interstitial + 1/4 plasma
2. C_x= U_xV/P_x (V = urine flow rate)
3. C_inor C_creatinine (normal GFR = 100 mL/min)
   
   • In + Cr are freely filtered neither reabsorbed or secreted
4. C_PAH
   
   • PAH is both filtered and actively secreted in the proximal tubule

Question 3

1. Filtration Fraction
2. filtered load
3. excretion rate
4. Reabsorption rate
5. Secretion rate

Answer 3

1. FF = GFR/RPF (normal = 20%)
2. Filtered load = GFR x P_x
3. Excretion rate= V x U_x
4. Reabsorption = filtered load - excretion rate
5. Secretion = excretion - filtered

Question 4

• PCT
• Thick descending limb of LH
• Thick ascending limb of LH

Answer 4

• reabsorbs all of the glucose and aa (via Na-dependent cotransporters) + most of HCO3, Na (65-80%), Cl, PO4, K+ and H20
  
  • isotonic absorption
  • generates + secretes NH3
  • ATII and CAI work here
• concentrating segment
  
  • passively reabsorbs H2O (impermeable to Na)
• diluting segment
  
  • actively reabsorbs Na, K and Cl (impermeable to H2O)
  • paracellular reabsorption of Ca and Mg
  • loops work here

Question 5

• Early DCT
• Collecting Tubule

Answer 5

• actively reabsorbs Na, Cl (urine is most hypotonic here)
  
  • thiazides work here
• reabsorbs Na in exchange for K+ and H+ excretion
  
  • aldo regulates insertion of Na channels (spironolactone compete with aldo and amiloride and triamterene antag Na channel)
  • ADH acts at V2 receptor –> insertion of aquaporin channels in medullary segment of CD

Question 6

1. Fanconi syndrome
2. Bartter syndrome
3. Gitelman syndrome
4. Liddle syndrome

Answer 6

1. reabsorptive defect in PCT –> may result in metabolic acidosis
2. reabsorptive defect in tALH –> hypokalemia and metabolic alkalosis with hypercalciuria
3. reabsorptive defect in DCT –> hypokalemia and metabolic alkalosis
4. increased Na reabsorption in distal and collecting tubules –> HTN, hypokalemia

the kidneys put out FaBulous Glittering Liquid

Question 7

RAAS

Answer 7

• JG cells secrete renin –> angiotensinogen –> angiotensin I –> angiotensin II (via ACE in lungs) –> angioII:
  
  • vascular smooth muscle –> vasoconstriction
  • constrict efferent arteriole of glomerulus –> increase FF
  • stimulate aldo secretion from adrenal gland
  • stimulate ADH secretion from post pit.
  • increased PCT Na/H activity
  • stimulates hypothalamus –> thirst
• ANP released in response to atriall stretch checks RAAS –> vasorelaxation of afferent arteriole via cGMP –> increases GFR and decreases renin

Question 8

1. shifts K+ out of cell
2. shits K+ into cell

Answer 8

1. digitalis, hyperosmolarity, insulin deficiency, cell lysis, Acidosis (H+ exchanges for K+), beta adrenergic antagonist
2. insulin, alkalosis, B-adrenergic agonist

Question 9

1. Metabolic acidosis
2. metabolic alkalosis
3. respiratory acidosis
4. respiratory alkalosis

Answer 9

1. low bicarb –> low PCO2 (hyperventilation response)
   
   • AG: Methanol, Uremia, DKA, Propylene glycol, Iron/INH, Lactic acidosis, Ethylene glycol, Salicylates (late) (MUD PILES)
   • non-AG: hyperalimentation, Addison, RTA, diarrhea, acetazolamide, spironolactone, saline infusion
2. hi bicarb –> high PCO2 (hypoventilation response)
   
   • loops, vomiting, antacid use, hyperaldosteronism
3. hi PCO2 –> hi bicarb (increased renal bicarb reabsorption)
   
   • hypovent: airway obstruction, acute lung disease, chronic lung disease, opiods, sedatives, resp mm fatigue
4. low PCO2–> low bicarb (decreased renal reabsorption)
   
   • hypervent: hysteria, hypoxemia, salicylates (early), tumor, PE

Question 10

RTA

• type 1
• type 2
• type 4

Answer 10

• distal; pH > 5.5; hypokalemia – defect in alpha intercalated cells of CD to secrete H+ –> new bicarb not regenerated
• proximal; pH < 5.5; hypokalemia – defect in PCT bicarb reabsorption
• hyperkalemic, pH < 5.5 – hypoaldosteronism, aldo resistance or K+ sparing diuretics

Question 11

1. Mannitol
2. Acetazolamide
3. loops

Answer 11

1. osmotic diuretic; act on PCT
   
   • use: high intracranial/intraocular P
2. CAI; act on PCT
   
   • use: glaucoma, metabolic alkalosis, altitue sickness (hypervent –> resp alkalosis)
3. Furosemide
   
   1. act on tALH – inhibit Na/K/2Cl transported
   2. Loops lose Ca
   3. otoxicity, hypokalemia, nephritis, hyperuricema, sulfa all
   4. use ethacrynic acid in sulfa allx

Question 12

1. Thiazides
2. K+ sparing diuretics
3. ACEI

Answer 12

1. act on DCT – inhibit Na/Cl contransporter
   
   1. use for idiopiopathic hypercalciuria (prevent Ca stones) and osteoporosis (retain Ca)
   2. toxicity: hypokalemia, hypercalcemia, met alkalosis, hyperuricemia, hyperlipidemia, hyperglycemia
2. act on CD
   
   1. spironolactone = aldo-dependent – antiandrogen effects
   2. triamterene and amiloride block Na channel induced by aldo
3. use in HTN, CGH, diabetic nephropathy, prevent unfavorable heart remodeling
   
   1. toxicity: increased Cr (decrease GFR), hyperkalemia, teratogen, cough, angioedema