What part of the heart separates the two halves?

The part of the heart that separates the two halves is called the septum. The septum consists of two main sections: the interatrial septum, which divides the right and left atria, and the interventricular septum, which separates the right and left ventricles. This structural division ensures that oxygen-rich and oxygen-poor blood do not mix, allowing for efficient circulation throughout the body.