Final answer:
The top chambers of the heart separated by the interatrial septum are the right and left atria, which receive blood from the body and lungs respectively.
Step-by-step explanation:
The top chambers of the heart that are separated by the interatrial septum are called the right and left atria. The atria are the chambers that receive blood; the right atrium gets blood from the superior and inferior venae cavae, while the left atrium receives oxygenated blood from the lungs through the pulmonary veins. The interatrial septum contains a depression called the fossa ovalis in adults, which is a remnant of the fetal heart's foramen ovale, allowing blood to bypass the pulmonary circuit before birth.