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Arterial blood flow

  1. Jun 17, 2009 #1
    Dear all,

    I am trying to find a mathematical explanation for why a blood vessel's lumen, especially an artery's, expands when the heart forces blood through the vessel upon contraction of the myocardium. This expansion is clearly evident when taking a person's pulse.

    I have some ideas but I am quite confused considering all of the variables.

    Firstly, I took the idea of volumetric flow rate and worked from there:
    [tex]Q=A\cdot v[/tex]

    Q blood flow rate through the vessel (volume per unit time)
    A cross-sectional area of the vessel lumen
    v velocity of blood flow

    Now I seem to remember that (area)(velocity) = constant, though this would imply that the the vessel would constrict as the velocity of the blood increases after a heart contraction!?

    I then took A, the cross-sectional area of the vessel lumen, and considered it in relation to blood pressure(from the pressure formula):
    [tex]A=\frac{F}{p}[/tex]

    F force exerted on the vessel wall by the blood


    ....AND there I got stuck. It has been annoying me all day and I would quite like to find an answer for it! I seem to be unable to link my medical knowlege with my physics knowlege at this point - perhaps I'm looking at the wrong variables.


    Many thanks,
    James
     
  2. jcsd
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