Understanding the Heart 

 
The heart is a muscle pump which circulates blood through your body. The right side of the heart pumps oxygen-poor blood returning from the body to the lungs where carbon dioxide is discharged and oxygen taken up. This oxygen-rich blood returns to the left side of the heart from where it is pumped to the body so that oxygen can reach all live tissue to keep you alive.
 
To ensure that blood flows in only one direction, there are four one-way valves in the heart. The Tricuspid and Pulmonary Valves are in the right side and the Mitral and Aortic valves are on the left side.

The heart is made of a remarkable type of muscle which beats non-stop for your entire life and requires constant supply of oxygen and nutrients which are provided through Coronary Arteries.

Disease  of the heart valves and of the coronary arteries can reduce your ability to exercise, make you breathless,  give rise to chest pains and can shorten you life.