It's All In The Lungs
Pulmonary circulation is the movement of blood from the heart, to the lungs, and back to
again. This is just one phase of the overall circulatory system.
The veins bring waste-rich blood back to the heart, entering the right atrium throughout
veins called vena cavae. The right atrium fills with the waste-rich blood and then
the blood through a one-way valve into the right ventricle. The right ventricle fills and
pushing the blood into the pulmonary artery which leads to the lungs. In the lung
exchange of carbon dioxide and oxygen takes place. The fresh, oxygen-rich blood enters the
pulmonary veins and then returns to the heart, re-entering through the left atrium. The
blood then passes through a one-way valve into the left ventricle where it will exit the
the main artery, called the aorta. The left ventricle's contraction forces the blood into
the aorta and
the blood begins its journey throughout the body.
The one-way valves are important for preventing any backward flow of blood. The
system is a network of one-way streets. If blood started flowing the wrong way, the blood
(oxygen and carbon dioxide) might mix, causing a serious threat to your body.
You can use a stethoscope to hear pulmonary circulation. The two sounds you hear,
"lub" and "dub,"
are the ventricles contracting and the valves closing.