Discuss the structure of the human heart and explain the double circulation of blood.

 

The human heart is a muscular organ with four chambers: two atria (upper) and two ventricles (lower). The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle, which sends it to the lungs for oxygenation. The left atrium receives oxygen-rich blood from the lungs and transfers it to the left ventricle, which pumps it throughout the body.

This process is called double circulation, as blood passes through the heart twice during one complete cycle—once for pulmonary circulation (heart → lungs → heart) and once for systemic circulation (heart → body → heart).

Double circulation ensures efficient oxygen supply to body tissues and separation of oxygenated and deoxygenated blood, which is essential for warm-blooded animals like humans.