Answer - Septum
The right side of the heart brings the deoxygenated (oxygen-poor) blood from other parts of the body toward the heart and the left side of the heart carries oxygenated (oxygen rich) blood from heart toward the other organs. The mixing of these two types of blood is prevented by a septum that divides the heart into two chambers: one for the oxygenated blood and the other for the deoxygenated blood.
Pericardium is a layer of covering on the heart that prevents friction build-up during cardiac activity.
