Anatomy of the heart

The heart is an organ that consists of four chambers: the left and right atria (the top chambers) and the left and right ventricles (the bottom chambers).  The left side of the heart receives oxygenated blood (blood containing oxygen) from the lungs and pumps it to the other organs, for example the brain, kidneys and liver.  The right side of the heart receives deoxygenated blood (blood with oxygen removed) from the body and pumps it to the lungs where oxygen is delivered once again.