Anatomy and Physiology II Practice Test

The left and right ventricles are separated by the interventricular septum, which is a thick wall of muscular tissue. This septum functions to prevent the mixing of blood between the two ventricles, ensuring that oxygenated blood is pumped out to the body from the left ventricle while deoxygenated blood is sent to the lungs from the right ventricle. The interventricular septum plays a crucial role in the efficiency of the heart's pumping action and contributes to maintaining proper circulation dynamics.

In contrast, the atrial septum separates the two atria, the coronary sinus is a vessel that collects deoxygenated blood from the heart muscle itself, and the pericardium is the fibrous sac that encases the heart. Each of these structures has a specific function but does not separate the left and right ventricles. Thus, the interventricular septum is the accurate choice for distinguishing the two ventricles.