Double circulation in a 4 chambered heart means that there are 2 circulations acting together in the cardiorespiratory system simultaneously. One circulation, is from the right ventricle to the lungs and back to the left atrium for oxygenation of the blood. The other circulation is from the left ventricle to the entire systemic circulation and back to the right atrium. Thus, considering that the heart beats 72 times in a minute, the blood goes through these double circulation 72 times.

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