The circulatory system of our body is like a system of different canals used for watering fields. Heart is the main organ of circulation from which arteries branch out in a network to reach the different parts of the body with the help of smaller vessels called Capillaries.
Veins, carry the blood back from various parts of the body to the heart. During this continuous circulation of blood, the heart does suction as well as compression. Thus, during this suction and compression, the heart beats, pumping about 12,000 lts. of blood everyday.
Below Heart Beat info from Wikipedia (Read More):-
The heart sounds are the noises (sound) generated by the beating heart and the resultant flow of blood through it. This is also called a heartbeat. In cardiac auscultation, an examiner uses a stethoscope to listen for these sounds, the heartbeat sounds like bassdrum, which provide important information about the condition of the heart.
http://en.wikipedia.org/wiki/Heart_sounds
