The heart is a muscular organ responsible for pumping blood throughout the body. Blood flow through the heart follows a specific sequence, passing through four chambers: two atria (right and left) and two ventricles (right and left). The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs, while the left side receives oxygenated blood from the lungs and pumps it to the rest of the body.
Ventricular fibrillation is deadly because it disrupts the heart's ability to pump blood effectively, leading to a lack of oxygen delivery to vital organs. Atrial fibrillation is usually not life-threatening by itself because the ventricles can still pump blood, albeit less efficiently, and maintain adequate blood flow through the body. However, atrial fibrillation can increase the risk of other serious conditions, such as stroke, due to the potential for blood clots to form in the atria.