The organ responsible for pumping blood in the human body is the heart. It is a muscular organ that functions as the core component of the circulatory system, ensuring that blood circulates throughout the body. The heart is divided into four chambers: the right atrium, right ventricle, left atrium, and left ventricle, which work together to pump oxygen-rich blood to the organs and tissues while returning deoxygenated blood to the lungs for oxygenation. The heart's rhythmic contractions are regulated by electrical impulses, making it a vital organ for sustaining life and maintaining overall health.