The wall called the interatrial septum separates which heart chambers?

• A. Interatrial septum separates the atria
• B. Interatrial septum separates the ventricles
• C. Interatrial septum connects atria to ventricles
• D. Interatrial septum separates the aorta and pulmonary artery

Answer: (A)

The interatrial septum is the wall that divides the heart’s two atria—the right atrium and the left atrium. This separation keeps the blood that returns from the body (which is low in oxygen) in the right atrium and the oxygen-rich blood from the lungs in the left atrium before it moves into the ventricles. It’s different from the wall between the ventricles (the interventricular septum), which separates the two lower chambers. The aorta and pulmonary artery are the major vessels that exit the ventricles, not separated by this atrial wall. In fetal life, blood can pass from right to left atrium through the foramen ovale, a passage that normally closes after birth.