Tuesday, October 11, 2011

The Physics of the Heart

The blood flow through the heart, or as physicists call it, hemodynamics, can be described by the equation: Flow= pressure difference on either side of the valve/the resistance to flow.  For example, when the blood is in the left ventricle, its next step is to move into the aortic arch, which then pumps the blood to the rest of the body.  However, this movement is blocked by a valve known as the aortic valve.  In order for this valve to open, the pressure in the left ventricle needs to be greater than that in the aortic arch.  Therefore, when measuring blood flow from the left ventricle to the aorta, the pressure difference would be the intraventricular pressure minus the aortic pressure.  When the left ventricle has a sufficient amount of blood in it, its pressure will surpass that of the aorta, and the valve will open.  Flow is also dependent on resistance, which refers to the relationship between the blood and its surroundings.  In the heart, resistance has to do with the size of the valve opening.  When the valve opening is small, the resistance is high, and the blood flow is slow. However, when the valve is large, the resistance is low, and the blood flow is fast.- written by Olivia McKennon

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