Cards (51)

    • What is one way to assess renal function?
      Investigate changes in filtration rate
    • How is glomerular filtration rate (GFR) measured?
      By assessing the clearance of substances
    • What is the imaginary substance used to explain GFR?

      W
    • What happens to substance W in the kidneys?
      It is freely filtered and not reabsorbed
    • If 720mg of W appears in urine over 24 hours, how much was filtered?
      720mg of W was filtered
    • What is the concentration of W in the plasma if it is 4mg/litre?
      4mg/litre
    • How much plasma contains 720mg of W at 4mg/litre concentration?
      180 litres of plasma
    • How is GFR calculated using inulin?
      By measuring its appearance in urine
    • What is the calculated GFR if 180 litres of plasma is filtered in 24 hours?
      125 ml/min
    • What substance is used to measure GFR in practice?
      Inulin
    • What is the first step to find the rate of absorption of phosphate?
      Measure GFR using the inulin technique
    • What is the plasma concentration of phosphate if it is 1 mmol/litre?

      1 mmol/litre
    • How much phosphate is filtered per day at a GFR of 165 litres/day?
      165 mmols of phosphate
    • If 40 mmols of phosphate are found in urine, how much is reabsorbed?
      125 mmols of phosphate
    • What does it indicate if the amount of substance excreted is greater than the amount filtered?
      Secretion must have occurred
    • What is renal clearance?
      • Volume of plasma cleared of a substance
      • Measured per unit time
      • Indicates kidney function
    • What is the clearance of inulin if it equals GFR?
      180 litres per day
    • How is the clearance of phosphate defined?
      Volume of plasma losing 40 mmol per day
    • What is the formula to calculate clearance of a substance?
      CX=C_X =mass of X excretedplasma concentration of X \frac{mass \ of \ X \ excreted}{plasma \ concentration \ of \ X}
    • What does it mean if clearance is less than C_IN?
      Substance has been absorbed in tubules
    • What is creatinine clearance useful for?
      It approximates GFR
    • What is creatinine a by-product of?
      Muscle metabolism
    • How is plasma creatinine used in assessing GFR?
      Increased plasma creatinine indicates reduced GFR
    • What is the normal plasma creatinine concentration?
      10 mg/litre
    • What happens to creatinine excretion if GFR is reduced?
      Creatinine excretion will decrease
    • What does an increase in plasma creatinine indicate?
      Possible reduction in renal function
    • What is one way to assess renal function?
      Investigate changes in filtration rate
    • How is glomerular filtration rate (GFR) measured?
      By assessing the clearance of substances
    • What is substance W in the context of renal clearance?
      An imaginary substance freely filtered
    • How does substance W appear in urine?
      By filtration alone, not reabsorption
    • If 720 mg of W appears in urine over 24 hours, how much was filtered?
      720 mg of W was filtered
    • What is the concentration of W in plasma if it is 4 mg/litre?
      4 mg/litre of W in plasma
    • How much plasma contains 720 mg of W at 4 mg/litre concentration?
      180 litres of plasma
    • What is the calculated GFR if 180 litres of plasma is filtered in 24 hours?
      180 litres/day or 125 ml/min
    • What substance is used to measure GFR in practice?
      Inulin, a freely filtered polysaccharide
    • How is GFR calculated using inulin?
      By measuring inulin's appearance in urine
    • What is the first step to find the rate of absorption of phosphate?
      Measure GFR using the inulin technique
    • What is the plasma concentration of phosphate (PO4-3) in the example?
      1 mmol/litre
    • If GFR is 165 litres/day, how much PO4-3 is filtered per day?
      165 mmols of PO4-3
    • What happens if 40 mmols of PO4-3 are found in urine?
      125 mmols of PO4-3 are reabsorbed