Renal Review Flashcards
What artery prevents a horseshoe kidney from ascending in the abdomen?
IMA
What fundamental problem creates Potter sequence?
oligohydramnios
classically from B/L renal agenesis
What are the three stimuli that induce renin release?
- beta adrenergic stimulation
- increased Na+ sensed by the macula densa
- increased pressure in afferent arteriole
What cell type releases renin?
JG cells (juxtaglomerular)
Kidney embryology
pronephros, mesonephros, metanephros
Pronephros
week 4; then degenerates
Mesonephros
functions as interim kidney for 1st trimester; later contributes to male genital system
Metanephros
permanent; first appears in 5th week of gestation
Where does the ureteric bud come from? What does it give rise to?
Ureteric bud is derived from the caudal end of the mesonephric duct
Ureteric bud gives rise to the ureter, pelvises, calyces, collecting ducts
How and what does the metanephric mesenchyme form?
Metanephric mesenchyme interacts with the ureteric bud, which induces differential and formation of glomerulus through the DCT
What is the POTTER sequence?
P - pulmonary hypoplasia O - oligohydramnios (cause) T - twisted face T - twisted skin E - extremity defects R - renal failure (in utero)
What is the anatomical relationship between the ureters and the ureter artery? Vas deferens?
The ureter passes under the uterine artery and the vas deferens
How does constriction of the afferent arteriole affect GFR, RPF, and FF?
decrease GFR, decrease RPF, no change in FF
What is the FF?
FF = GFR/RPF
How does constriction of the efferent arteriole affect GFR, RPF, and FF?
increase GFR, decrease RPF, increase FF
What effect does angiotensin II have on the glomerulus?
angiotensin II preferentially constricts the efferent article -> increase GFR, decrease RPF, increase FF
What effect do prostaglandins have on the glomerulus? What inhibits this?
prostaglandins preferentially dilate the afferent arteriole -> increased GFR, increased RPF, no change in FF
NSAIDs inhibit this
How does dilation of the afferent article affect GFR, RBF, and FF?
increase GFR, increase RBF, no change in FF
How does dilation of the efferent arteriole affect GFR, RBF, and FF?
decrease GFR, increase RBF, decrease FF
How does an increase in serum protein affect the GFR, RBF, and FF?
decrease GFR, no change in RBF, decrease FF
How does a ureter stone obstruction affect the GFR, RBF, and FF?
decrease GFR, no change in RBF, decrease FF
How do ACE inhibitors affect the GFR, RBF, and FF?
decrease GFR, increase RPF, decrease FF
What is the 60,40,20 rule?
60% of body weight = total body water in L
40% of body weight = intracellular fluid
20% of body weight = extracellular fluid
How much of extracellular fluid is made up of plasma volume?
25%
A 40-year-old patient of yours weighs 100kg. What is her estimated plasma volume?
5L
20L x 0.25
At what glucose concentration is the tubular reabsorption of glucose maximized?
350 mg/dL
~160-200 -> start spilling glucose
What vitamin deficiency results from Hartnup disease?
niacin (Vit B3)
What are the symptoms of niacin deficiency?
pellagra 3D's diarrhea dermatitis dementia
What substances can be used to estimate GFR? What substitutes can be used to estimate renal plasma flow?
estimate GFR with inulin CL or Cr CL
estimate RPF with PAH CL
What is the equation for the renal clearance of any substance?
CL = urine conc. x urine flow rate/plasma conc
excretion rate = urine conc. x urine flow rate
Hartnup diesase
deficiency in transporter of neutral amino acids, such as tryptophan -> with no tryptophan, can’t make niacin -> 3 D’s of pellagra
What is filtered in the proximal tubule?
all glucose, all amino acids, 2/3 fluid, 2/3 electrolytes
What is reabsorbed in the first half of the proximal tubule? What kind of transporter do they use? What is it driven by?
glucose, amino acids, Pi, and lactate
Na+ cotransporter
driven by Na+ gradient, which is maintained by the Na+/K+ ATPase
How is bicarbonate reabsorbed in the first half of the proximal tubule?
HCO3- is broken down by carbonic anhydrase, and the H+, CO2, and H2O all cross into the tubular cell where carbonic anhydrase turns it back into HCO3- where it is transported via Na+ and Cl- cotransporters
What does TF/P < 1 signify?
reabsorbing more quickly than H2O
What does TF/P > 1 signify?
solute reabsorbed slower than H2O
If a substance filtered by the kidney has a TF/P > Cr, what does this mean?
the substance is being actively secreted by the kidney (such as PAH) because Cr and inulin are not reabsorbed, only filtered
What is reabsorbed in the second half of the proximal tubule?
Na+ and Cl-
How are organic anions secreted in the proximal tubule?
in exchange for alpha ketoglutarate
How are organic cations secreted in the proximal tubule?
in exchange for H+
What is true of the thin descending limb in relation to water/Na+ reabsorption?
impermeable to Na+
Thin descending limb is responsible for water reabsorption
H2O follows osmotic gradient into hypertonic medulla -> luminal fluid becomes more concentrated
What important cotransporter is located in the thick descending limb? What is true of H2O reabsorption here?
Na+/2Cl-/K+ cotransporter
TAL is impermeable to water
How are Ca2+ and Mg2+ reabsorbed in the TAL?
between cells
What is true of the concentration of the filtrate in the TAL?
TAL is impermeable to water, but the filtrate is still becoming less concentrated because all the cations are leaving
Where does PTH act in the kidney?
early distal tubule
What is true of H2O reabsorption in the early distal tubule?
impermeable to water
What two types of cells compose the collecting duct and the last segment of the distal tubule? What do they do?
- principal cells -> reabsorb H2O and Na+; secrete K+
2. intercalated cells -> secrete H+ or HCO3-; reabsorb K+
What are the two types of intercalated cells? What do they each do?
- alpha cells (A cells) -> secrete H+
2. beta cells (B cells) -> secrete HCO3-
What determines how much water is reabsorbed in the distal tubules and the collecting ducts?
ADH (vasopressin)
What drug inhibits aquaporins at the collecting tubule?
lithium
What class of diuretic directly affects the principal cells?
potassium-sparing diuretics
Inhibit epithelial Na+ channels in collecting tubules -> triamterene, amiloride
Aldosterone antagonists -> spironolactone & eplerenone
What effect does aldosterone have on the principal cells and intercalated cells of the collecting duct?
principal cells - reabsorption of Na+, secretion of K+
intercalated cells - stimulates secretion of H+
What causes K+ to shift out of the cells (hyperkalemia)?
low insulin (hyperglycemia) beta blockers acidosis digoxin cell lysis (leukemia)
What causes K+ to shift inside the cells (hypokalemia)?
insulin
beta-agonists
alkalosis
cell creation/proliferation
What is the treatment for hyperkalemia?
IV bicarb
beta-agonist (albuterol)
IV insulin + dextrose
IV Ca2+ to prevent arrhythmias (always do this first)