Day and night, the muscles of your heart contract and relax to pump
blood throughout your body. When blood returns to the heart, it follows
a complicated pathway.
If you were in the bloodstream, you would follow the steps below one by
one.
2. Blood flow through the right atrium into the right ventricle.
3. The right ventricl pumps the blood
to the lungs, where the
blood releases waste gases and picks
up oxygen.
4. The newly oxygen-rich blood (shown in red) returns to the heart and enters the left atrium.
5. Blood flows through the left atrium
into the left ventricle.The left ventricle pumps the oxygen-rich blood
to all parts of the body.