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April 11, 2018

Vascular Resistance

The sampled artery in this kidney biopsy shows severe arteriosclerosis.  The deleterious effects of a narrowed arterial lumen and increased stiffness of the artery wall are illustrated mathematically:  resistance to blood flow is directly proportional to vessel length and blood viscosity and inversely proportional to vessel diameter (or radius).  This formula illustrates how vessel diameter (or radius) has the most profound effect on resistance, especially since vessel length and blood viscosity do not usually change significantly in most physiologic states.