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the human heart contracts from the first moment of life in the last one. the contractions of the heart pump the blood through the arteries to all the parts of the body. scientists have determined that the total weight of the blood pumped by the heart daily is about ten tons.the rate of heart contractions is regulated by two groups of nerve fibers. it varies in different persons and at different age.Physiologists have determined that in the example, the heart is from 60 to 72 beats per minute. in children the rate of heartbeat is much higher. research work of many with has helped to determine that the rate of heartbeat increases between on different really.each beat of the heart is followed by a period of rest for the cardiac, australia. each wave of the stella and a period of rest following it has a cardiac cycle.research work has given physiologists the possibility to find out that the heart of australia or contracts about one third of the time of the person"s life. the period of rest is shorter and greater physical exertion and longer when the body is at rest.each cardiac cycle consists of three phases: the first phase of physiologists have called on the stella will atria - the atrial systole. they have called the second phase of a more prolonged stella will ventricles - the ventricular systole. the period of rest of the cardiac australia is called the diastole.the left ventricle discharges out the blood received by the left atrium from the pulmonary circulation through the aorta to the systemic circulation.the blood received from the systemic circulation by the right atrium is discharged out of the right ventricle to the lungs through the pulmonary arteries.prolonged research work of many physiologists has given the possibility to estimate the role of the ventricles which serve as the main pump. the atria act as receiving chambers. the stella of the atria which sends the final portion of the blood into the ventricle is considerably less.
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