... is repeated endlessly until the organism dies. The heart does not push the blood miraculously on its own; it is assisted by pacemaker cells [sinoatrial node and the atrioventricular node]. These cells cause the heart muscles to contract rapidly, thus flushing out the blood to either the lungs or to the body depending on the ventricle. In a nutshell, the heart works tirelessly through out an organism's life pumping vital oxygen to the body. By the time you had read this summary a mouse's heart would have beaten approximately a 1000 times! [500 beats per minute * 2minutes] this just shows that this little machine is made for endurance; unfortunately we humans abuse it by overworking it [over eating/ no exercise]. Without the heart, there will be no circulation of much needed elements such as oxygen, which is carried by the blood, to the body and we would die within ...

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