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"Blood Pressure." 15 February 2005. HowStuffWorks.com. <http://health.howstuffworks.com/adam-200079.htm> 13 May 2008.
Blood Pressure
One of the heart's most important functions is maintaining normal blood pressure in the body. Both abnormally high and abnormally low blood pressure can cause medical complications. This animation describes the factors that affect blood pressure and how the heart keeps it steady.
If the animation above isn't working, click here to get the Shockwave player.