The body extracts oxygen from the blood turning the blood a dark blue color. Large veins return this blue blood to the heart.
The blood from the body enters the right upper collecting chamber (right atrium or RA) and from there, passes through a valve to the right-sided pumping chamber (right ventricle or RV).
The right ventricle (RV) then pumps the blood to the lungs where the blood picks up oxygen and turns a bright red color. The lungs also filter the blood of small clots and other debris.
The red, oxygen-rich blood then returns from the lungs to the left upper collecting chamber (left atrium or LA) and from there passes through a valve to the left-sided pumping chamber (left ventricle or LV)
The left ventricle (LV) then pumps the oxygen-rich, red blood to the aorta which is the large blood vessel that carries the blood to the body.