5. Determination of Volumes of Specific Fluid Compartments

Cards (20)

  • What substances can be used to measure total body water?
    Radioactive water and heavy water
  • How do tritium and deuterium measure total body water?
    They mix with total body water after injection
  • What principle is used to calculate total body water?
    The dilution principle
  • What is another substance used to measure total body water?
    Antipyrine
  • Why is antipyrine effective for measuring total body water?
    It is lipid soluble and penetrates cell membranes
  • How can extracellular fluid volume be estimated?
    Using substances that disperse in plasma
  • What types of substances are used to measure extracellular fluid volume?
    Radioactive sodium and chloride
  • How long does it take for substances to disperse in extracellular fluid?
    30 to 60 minutes
  • What is meant by "sodium space" or "inulin space"?
    It refers to measurements of extracellular fluid
  • How is intracellular volume calculated?
    By subtracting extracellular volume from total body water
  • What substance is commonly used to measure plasma volume?
    Radioactive iodine-labeled serum albumin
  • Why must a substance used to measure plasma volume not penetrate capillary membranes?
    To ensure it remains in the vascular system
  • What dye can be used to measure plasma volume?
    Evans blue dye
  • How is interstitial fluid volume calculated?
    By subtracting plasma volume from extracellular fluid volume
  • How can blood volume be calculated?
    Using plasma volume and hematocrit
  • What equation is used to calculate total blood volume?
    Total blood volume = Plasma volume / (1 - Hematocrit)
  • If plasma volume is 3 liters and hematocrit is 0.40, what is the total blood volume?
    5 liters
  • How can blood volume be measured using labeled red blood cells?
    By measuring radioactivity in a blood sample
  • What radioactive material is commonly used to label red blood cells?
    Radioactive chromium (51Cr)
  • Why is radioactive chromium used for labeling red blood cells?
    It binds tightly with red blood cells