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Renal Blood Flow

  • The volume of blood flow to the kidneys is a key physiological variable as it determines the rate at which the kidneys can filter and process the body's extracellular fluid. In general, the kidneys receive nearly 20% of the total body's cardiac output over a very wide range of systemic arterial pressures. Importantly, the vast majority of renal blood flow is directed through the renal cortex and only a small minority travels through the renal medulla. This arises from the fact that the only vessels that perfuse the renal medulla are the vasa recta which are rather few. Because of this tenuous blood supply the renal medulla is highly prone to infarction, yielding renal infarction.
  • As discussed in hemodynamic integration the blood flow volume to a particular section of vasculature is purely determined by the blood pressure gradient across it and its resistance. When applied to the kidneys as entire organs the relationship is as follows:
  • Total Renal Blood Flow Volume = (Renal Artery Pressure - Renal Vein Pressure) / Total Renal Resistance