The right ventricle pumps the blood to the lungs, where the blood releases waste gases and picks up oxygen. The newly oxygen-rich blood (shown in red) returns to the heart and enters the left atrium.

The heart is under the rib cage, to the left of your breastbone (sternum) and between your lungs. On the outside, the heart is made of muscle. The strong muscular walls contract (squeeze), pumping ...

“Suspended animation ... If the patient’s heart does not start on its own after blood is pumped, doctors will resuscitate the patient with a heart-lung bypass machine.