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Effect of peripheral resistance on arterial pressure

  1. Sep 21, 2008 #1
    Hi, I know that arterial pressure increases as peripheral resistance increases. This is because blood begins to back up from the point of increased resistance and a greater volume causes greater pressure in the arteries. Also, the more stiff or rigid the artery the greater the pressure change will be. However, how come in many circuits by increasing resistance the voltage (analog of pressure) does not change but rather the current (analog of flow rate) changes. I know voltage does not change because it is a function of the battery. However why and how does current change?, why the difference between the two systems? Thank you.

    I didn't know whether to put this in the physics or biology forum.
     
    Last edited: Sep 21, 2008
  2. jcsd
  3. Sep 22, 2008 #2

    Moonbear

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    In the cardiovascular system, there is an increased pressure leading up to the site of occlusion, but through the narrowed section of arteries, there is also an increased flow rate. Blood vessels, however, are not rigid, except in areas of occlusion. So, as pressure increases, so does the vessel volume, and eventually, the ventricle of the heart (left ventricle if the problem is in most of the body, right ventricle if the increased resistance is due to pulmonary obstruction). This begins to gradually work backward through the entire cardiovascular system. When the organs reach a point where they can no longer expand to accomodate the pressure increases, in the case of blood vessels, they may rupture (i.e., ruptured aneurysms), or in the case of the heart, it simply ceases to have the strength to continue beating. In either case, you die when it reaches that point (without immediate medical intervention).
     
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