The work accomplished by the heart is out of proportion to its size. The heart functions normally throughout one's lifespan for most people.
Heart is a Double Pump
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During the 70 years in the life of an average person, the heart will pump approximately 4.732 liters (5 US quarts) of blood a minute, 283,906 liters (75 gallons) an hour, 6796.71 liters (57 US barrels) a day, and 178,860,7065 liters (1.5million US barrels) in a lifetime.
Preload
Afterload
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Cardiac Output is a traditional measure of cardiac function. Cardiac output is the amount of blood, in liters, ejected from the left ventricle each minute. Cardiac output is the product of heart rate (HR) and stroke volume is the volume of blood ejected per ventricular contraction. Normal cardiac output for an adult ranges from 4 to 8 liters a minute and can be changed to meet changing bodily demands for tissue perfusion, but the cardiac output equation does not account for differences in body size. An output of 5L/min might be sufficient for a 50kg man, but insufficient for a 120kg man.
Circulatory System
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The pumping action of the heart moves blood, which is a vital substance, throughout the body, supplying oxygen and nutrients to cells and removing waste. Without this action cells in the body will die. To pump effectively, the heart muscle must begin contraction as a single unit. Cardiac muscle (myocardial) cells are endowed with extraordinary characteristics, most of which belong to the cell membrane.
Heart problems
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For people in whom cardiac problems develop, the results may be dramatic and the outcome drastic.
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