Final answer:
The interventricular septum separates the right and left ventricles, while the interatrial septum separates the right and left atria of the heart.
Step-by-step explanation:
The interventricular septum and interatrial septum are important internal structures of the heart. The interventricular septum separates the right and left ventricles, which are the lower chambers of the heart responsible for pumping blood to the lungs and the rest of the body, respectively. This septum is particularly thick, as it needs to withstand the high pressure generated when the ventricles contract. In contrast, the interatrial septum separates the right and left atria, the upper chambers of the heart that receive blood returning to the heart from the body and the lungs. The interatrial septum features a depression known as the fossa ovalis, which is a remnant of the fetal foramen ovale that closes soon after birth to establish normal cardiac circulation.