How a Normal Heart Pumps Blood
The normal heart has two sides: a right side and a left side, and four chambers: the top receiving chambers, or atria, and the lower chambers, which are thick-walled pumping chambers, called ventricles.
Red blood cell will come from either the superior vena cava or the inferior vena cava and enter into the right atrium. The blood then flows across the tricuspid valve to the right ventricle. The right ventricle then squeezes and ejects that blood cell into a vessel called the "pulmonary artery."
The pulmonary artery splits into two vessels, each going to the lungs. As that red blood cell makes its way through the lung, it returns through the pulmonary veins to the left atrium. That blood is now oxygenated. It's picked up oxygen then goes across the mitral valve into the left ventricle, which does most of the work in terms of delivery of blood flow to the body. That blood cell is now ejected into the aorta to some organ or muscle or skin in the human body.
Normal Heart Transition After Birth
As soon as the cord is clamped, the ductus venosus ceases to carry blood to the heart, and it begins to constrict within the first few hours or days of life.
The very first thing that happens when the fetus is born is it takes its first breath, the lungs expand, and so the resistance, or pressure, in the lungs drop, and that promotes blood flow into the lung itself.
The ductus arteriosus begins to constrict and is typically fully closed within 24 to 48 hours of life. And blood is now then fully directed into the lung. As the blood returns to the left side of the heart after traversing the pulmonary circulation and picking up oxygen, the pressure in the left atrium rises just a bit. And the trap door of the foramen ovale, which was opened before birth, now begins to close, usually within the first few days of life.
Related Centers and Programs: Cardiac Center