Hemodynamics, Dr. D. Penney

Classes of Vascular Resistance

  • Functional (dependent upon smooth muscle contraction): altered tone in arteries, arterioles, veins, etc.

  • Fixed (chronic anatomical and pathological changes):
    arteriosclerosis, coarctation of aorta, shunts (e.g. ventricular septal defect), pulmonary vascular obstructive disease, valvular insufficiency and stenosis, blood viscosity?

  • Passive (dependent upon posture/gravity; usually transient)
    vessel closure due to decreased transmural pressure
    vessel closure due to organ/bone weight

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