Normal Heart
These diagrams show the structurally normal heart and how blood usually circulates. The heart is a pump, where “used” blood (oxygen depleted) pictured by the blue arrows, is pumped into the heart from the upper and lower body through the inferior and superior vena cavae (IVC and SVC). The blue blood enters the collecting chamber, known as the right atrium (RA), where it waits for the tricuspid valve (TV) to open into the right ventricle (RV). The muscular right ventricle (RV) pumps blood through the pulmonary valve (PV) out into the branch pulmonary arteries (PA). The PA s are directly connected to the lungs, where blood is filtered through to pick up oxygen.
The red arrows denote the oxygen-rich blood. Note that the red arrows enter the left collecting chamber, the left atrium (LA) through at least four pulmonary veins which are hooked into the back of the LA directly from the lungs. The red blood hangs out in the LA until the mitral valve (MV) opens into the muscular pumping left ventricle (LV). The LV pumps blood through the aortic valve (AoV) into the aorta (AO) where the oxygen rich blood is sent throughout the body.
Notice that there are usually no natural holes * between the collecting chambers and the pumping chambers of the heart. Similarly, there are usually no blood vessels connecting the pulmonary artery (ies) to the aorta.
*The exception is the patent foramen ovale (PFO), which is a remnant from birth and may naturally stay open in an estimated 25% of the population.
