Heart is a thick, muscular, and atomic pumping organ of the blood vascular system. It remains safe within the pericardium membranes. Its weight is about 300 grams. The chambers which receive the blood from the body tissue are called atria, and the chambers of the heart which pump blood to the body tissues are called ventricles. A newborn baby’s heart weighs about 20 grams. The heart is encased in a thin two-layered sac known as the pericardium, filled with a watery fluid called pericardial fluid, which allows frictionless movement of the heart and protects it from mechanical stress. The blood in veins is typically impure, meaning it is carbon dioxide-enriched blood. Pulmonary veins are an exception as they always carry pure (oxygenated) blood to the heart. The heart chambers function by alternating contractions called systole and relaxation called diastole. The regular sequence of these systoles and diastoles creates the heart sounds “lub” and “dub”. The normal resting heart rate is about 70 to 72 beats per minute but can be higher, around 140 beats per minute, in infants. The SA node (sinoatrial node) coordinates the contractions of the heart, ensuring a rhythmic and consistent heartbeat. The wave of contraction initiated by the SA node is picked up and relayed by the AV node (atrioventricular node), ensuring thorough pumping action. Additionally, the heart is composed of four primary chambers: the right atrium, right ventricle, left atrium, and left ventricle. The right atrium receives deoxygenated blood from the body through the superior and inferior vena cava, and the right ventricle pumps it to the lungs for oxygenation via the pulmonary artery. Oxygenated blood returns to the left atrium via the pulmonary veins and is then pumped to the rest of the body by the left ventricle through the aorta. The heart’s efficiency in circulating blood is also supported by coronary arteries, which supply the heart muscle with essential nutrients and oxygen, ensuring its optimal function.