Flow Through Blood Vessels

Today, while studying for my upcoming transport test I became mindful that the flow through human blood vessels can be modeled by the flow of fluid through a circular pipe. Flow in blood vessels is always laminar and will always have a parabolic velocity profile. Blood vessels do not operate under steady-state, steady-flow conditions, the heart is a pulsating pump and the flow and pressure varies over time. You would have to average the velocities and flowrates over time, introducing error in the calculation.