Poiseuille's law: halving vessel radius
If a blood vessel's radius is halved and the pressure difference along it stays the same, what happens to the flow rate?
Answer D: explanation for every choice
A
This assumes flow is proportional to r.
B
This assumes flow is proportional to r², as for cross-sectional area.
C
Radius strongly affects resistance and flow.
D
Correct. Poiseuille's law says flow ∝ r⁴, so (½)⁴ = 1/16.
TakeawayPoiseuille's law: Q ∝ r⁴ΔP/(ηL).
Equation usedPoiseuille's law
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