As a complete system, the amount of blood that flows through the circulatory
system is in terms of the pressure difference between the arteries and the veins
times the quantity referred to as the total peripheral resistance. But what about
at the local level? How much blood flows through an individual blood vessel? What
are the quantities that affect the rate of blood flow? This exhibit discusses
a physical relation known as Poiseuille's Law which partially answers this
question.
Poiseuille's Law relates the rate at which blood flows through a small blood
vessel (Q) with the difference in blood pressure at the two ends (P), the
radius (a) and the length (L) of the artery, and the viscosity (n) of the blood.
The law is an algebraic equation,
You can explore this law as it applies to arterioles through a number of
categories, which are organized as follows: