Without rest if the heart?

A body the size of a fist and weight of 300 g does a great job. During the day, the heart is reduced even at rest over 100 thousand times, and with each contraction throws blood into the aorta with such force that would be able to raise the column of blood almost 1.5 m Pumping every systole 150 cm3 vessels in (75 cm3 from the left ventricle to the aorta and from the right in the pulmonary artery), the heart pumps per day over 15 thousand liters of blood. It should be borne in mind that when exercise the heart significantly increases its work. It can throw into the aorta when one systole exceeding 150 cm3 blood, moreover its rate cuts may reach the athlete at the finish 240 beats per minute or more. If alone in the heart ejects the aorta for a minute about 4 liters of blood, then the athlete's this minute volume of circulatory comes when some competitions to 25 litres, i.e. up to 3 buckets and near several prominent representatives of sports was marked record figures in excess of 40 liters per minute, or 5 buckets.
Reader, have not lost a friendship with arithmetic, apparently, and he himself went up to this figure. As shown earlier, the highest impact (single) volume and heart rate exceeding 150 cm3 and more than 240 blows per minute, in fact, would have to give the minute volume of circulatory about 40 liters. However, it is only in isolated cases. The thing is that record-high level of stroke volume and frequency of cardiac contractions usually not be at the same time. Most stroke volume is observed at the heart rate 150-160 beats per minute, at frequency 200 beats per minute and up stroke volume decreased again, for your heart for short periods between contractions not time enough to fill with blood.
How heart does his great work? We often hear such questions. Heart, we are told, works continuously, not resting for a single minute, throughout life. How is it not tired? After all, the brain 2/3 days work, then one third of the rest... Why the heart does not need rest?
The people who ask this question, many are surprised to learn that the heart is at rest, in any case, more than the brain. However, it rests in the process of the work itself. We have said that each systole replaced by a relaxation, diastole. Decreased heart, worked 0.3 seconds, and then 0.5 to 0.6 seconds of it rests. So, it actually rests almost 2/3 of the time, but knows how to do it, so to speak, without discontinuing work. The brain can't do it; it accumulates in need of a holiday for the whole day continuous voltage higher centers - our sphere of consciousness. At least a third time -- more it does not claim the brain must be restored.