The inner wall which acts as separation between the atria and the ventricle to play an important function related to the blood.
The human heart has two sides- right side and the left side as shown in the diagram below. There are ventricles and atrium present in the both sides named as right ventricle, left ventricle and right atrium, left atrium. These atrium and ventricles have valves if we look at the diagram carefully. These two sides of the heart are separated by the inner wall called Septum.
Septum have generally two parts i.e., Ventricular septum and Atrial septum. Ventricular septum forms a barrier between left and the right ventricle. Atrial septum forms a barrier between left and the right atrium.
With each heartbeat, the deoxygenated blood is received by the right side from the body which pumps it to the lungs where the blood becomes oxygenated and then this oxygenated blood is received by the left side from the lungs and it pumps it to the other parts of the body.
In this process, septum plays an important role, it separates the atria and the ventricle in such a way that it kind of forms a barrier between the chambers of the heart which prevents the mixing of oxygenated (oxygen-rich) and deoxygenated blood (oxygen-poor). Without septum, oxygenated blood cannot be separated properly.
Thus, the role of septum is to prevent the mixing of the oxygenated which is oxygen rich and deoxygenated which is oxygen poor blood.
Note: Septum plays a major role in separating the both sides of heart in order to prevent the mixing of oxygen rich and oxygen poor blood otherwise both of these will get mixed and there will be no separation between them and the entire process of the heart will get disturbed. Therefore, it plays an important role in the heart.