Some "Interesting" Circulatory Volume/ Hemodynamics


This diagram illustrates the following:

  1. Keep in mind that even tiny changes in the average arteriolar diameter (or radius, if you prefer) can markedly alter the TPR; the relationship of radius- (the term "r" in the following equation) and vessel resistance, is shown according to the following:
  • Resistance = (Viscosity & Length Constants) x (r)-4

...where "r" refers to the radius of the cross section of a vessel...Thus resistance increases as the inverse of the 4th power of the radius.

  • ....therefore, a simple change of only 16% in the average radius of the pressure vessel can double (or halve) the TPR!!

To Hypertension

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