A "beating heart" refers to the rhythmic contraction and relaxation of the heart muscle, which pumps blood throughout the body. This process is essential for delivering oxygen and nutrients to tissues while removing waste products. The heart has four chambers: the left atrium, right atrium, left ventricle, and right ventricle, which work together to maintain circulation. The heartbeat is regulated by electrical signals that originate from the sinoatrial node, often called the heart's natural pacemaker. These signals ensure that the heart beats in a coordinated manner, typically at a rate of 60 to 100 beats per minute in a resting adult.