If the radius of a blood vessel decreases by half due to vasoconstriction, which consequence follows regarding blood flow, assuming constant pressure gradient and blood viscosity?

💡 Explanation

The effect of vessel radius on blood flow is described by Poiseuille's Law, where flow is proportional to the radius to the fourth power. Because the radius decreases by half, the flow decreases by (1/2)^4 = 1/16; therefore, blood flow decreases sixteen-fold, rather than remaining constant or decreasing linearly.

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