Renal Flashcards
How is plasm volume measured?
Radiolabeling albumin
How is extracellular volume measured?
Inulin or mannitol
Patient with Addison’s disease experiences what kind of volume shift?
Hypoosmotic volume contraction
What cells synthesize renin? Where are they located?
Juxtaglomerular smooth muscle cells contained in the afferent arteriole
How are RBCs prevented from filtration in the glomerulus?
Fenestrated capillaries
What is the equation for renal clearance?
Clearance of substance X = (urine concentration of X * urine flow rate)/plasma concentration of X
If clearance of substance is less than GFR, what does this mean?
Net tubular reabsorption of substance
If clearance of a substance is greater than GFR, what does this mean?
Net tubular secretion of substance X
What is renal clearance?
Volume of plasm cleared of a substance per unit of time
Inulin can be used to measure what?
GFR or extracellular volume
How is effective renal plasma flow estimated?
Para-aminohippuric acid clearance
How is renal blood flow calculated?
Renal plasma flow / (1-Hct)
What affect does probenecid have on penicillin?
It increases the half life of penicillin by inhibiting penicillin secretion in the proximal tubule via blocking the PAH transporter
Penicillin is secreted in the kidney by what transporter? Where?
Para-aminohippuric acid transporter in proximal tubule
What is the equation for calculating filtration fraction?
GFR/RPF
What is a normal filtration fraction?
20%
How do you calculate the filtered load?
GFR x plasma concentration
How is renal plasma flow estimated?
Para-aminohippuric acid
With an increased filtration fraction, what happens to protein concentration in peritubular capillary blood? What affect does this have on the nephron?
Increased protein concentration in peritubular capillary blood; which leads to increased reabsorption of water in the proximal tubule
What affects does decreased filtration fraction have on peritubular capillaries and the nephron?
Decreased protein concentration in the peritubular capillaries and decreased reabsorption of water in the proximal tubule
In dehydration what happens to GFR, RPF, and FF?
Decrease in GFR, large decrease in RPF, and therefore increase in filtration fraction
What affects do prostaglandins have on afferent arteriole? NSAIDs?
Vasodilate; NSAIDs cause vasoconstriction, could result in decreased GFR and therefore ischemia to kidney
How is the excretion rate calculated?
Urine flow rate x urine concentration of substance
What is the reabsorption rate?
Filtered - excreted
What is secretion rate?
Excreted - filtered
What is the equation for FENa?
(Plasma creatinine x Urine Na) / (Urine creatinine x Plasma Na)
What is seen on light microscopy from a section of the proximal convoluted tubule?
Simple cuboidal epithelium with brush border
What is seen on light microscopy from a section of the distal convoluted tubule?
Simple cuboidal epithelium with NO brush border
What type of epithelium is seen in the thin descending loop of Henle?
Simple squamous
What region of the nephron does PTH act to increase calcium reabsorption?
DCT
Where does PTH act in the kidney? What does it do?
Proximal to increase phosphate excretion and DCT to increase calcium reabsorption
What is Winter’s formula?
Pco2 = 1.5 [HCO3-] + 8 +/- 2
What is winters formula used for?
In simple metabolic acidosis, it can be used to calculate predicted resp compensation
If measured Pco2 is greater than the predicted Pco2 from winters formula, what is going on?
Concomitant respiratory acidosis
If measured PCO2 is less than predicted PCO2, what is going on?
Concomitant respiratory alkalosis
What drugs/nephrotoxins can cause Fanconi syndrome?
Ifosfamide, cisplatin, tenofovir, expired tetracyclines, lead poisoning
Expired tetracyclines can cause what syndrome?
Fanconi syndrome?
What is fanconi syndrome?
Generalized defect in reabsorption in PCT; cannot reabsorb glucose, aa, HCO3, and PO4
Fanconi syndrome can result in what acid/base disorder?
Metabolic acidosis - proximal tubular acidosis
Barter syndrome is a defect in what transporter?
NKCC2
What part of the renal tubule is affected by Bartter syndrome?
Thick ascending limb