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Please help with this subject question :-(

Discussion in 'Medical Students - DO' started by rsweeney, Mar 28, 2004.

  1. rsweeney

    rsweeney Senior Member
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    How would decreased venous compliance [more blood returned to heart] affect the function of the cardiac cycle in terms of preload, afterload, stroke volume, cardiac output, etc.---especially afterload. What would the PV-loop look like compared to the control loop?

    My mind is going bonkers

    +pissed+ :scared:
     
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  3. Dr JPH

    Dr JPH Membership Revoked
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    Increase preload, increase stroke volume, increase cardiac output.

    Long term may change as the heart modifies to accomodate.

    You may also hear S3.
     
  4. rsweeney

    rsweeney Senior Member
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    So, in time, the increased cardiac output will increase mean arterial presure thus increase afterload. Then, when afterload incrases, the ventricle will eject less blood so end diastolic volume will rise too. Is this correct?
     
  5. Cowboy DO

    Cowboy DO Senior Member
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    PV loop for someone with hypertension is taller (with increased pressure on the Y axis) but the same width (with SV on the X axis) indicating more work for the same amount of blood ejection.

    I dont have time right now to double check what your saying, I have tests this week and should be studying, but i will eventually. Or post when you get a deffinitive answer, but something looks funky with what youre saying.
     
  6. Kalel

    Kalel Membership Revoked
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    That is correct, although it's not a matter of "in time". An increase in cardiac output will lead to an immediate increase in mean arterial pressure, which will mean an increase in afterload and end diastolic volume. It's part of what happens when you exercise.
     

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