ANATOMY

Detailed explanation-1: -The hole between the top two heart chambers (right and left atrium) is called a patent foramen ovale (PFO). This hole allows the oxygen rich blood to go from the right atrium to left atrium and then to the left ventricle and out the aorta. As a result the blood with the most oxygen gets to the brain.

Detailed explanation-2: -Inside the fetal heart. Blood enters the right atrium. This is the chamber on the upper right side of the heart. When the blood enters the right atrium, most of it flows through the foramen ovale into the left atrium.

Detailed explanation-3: -Before birth, the foramen ovale allows blood flow to bypass the lungs (a fetus gets the oxygen it needs from the placenta, not the lungs). That way, the heart doesn’t work hard to pump blood where it isn’t needed. When newborns take their first breath, a new flow direction happens.

Detailed explanation-4: -Oxygen-rich blood gets to the heart through the vein that drains blood from the body to the right upper heart chamber. This vein is called the inferior vena cava. The blood then goes across the foramen ovale and into the left upper heart chamber.