This audio podcast will cover the gross anatomy of the heart and circulatory system and explain how the heartbeat is controlled. The heart is made up of 4 chambers, 2 atria and 2 ventricles, which coordinate the circulation of blood through the pulmonary and systemic circulations. The heartbeat is initiated by pacemaker cells which produce an impulse which is propagated throughout the heart. This podcast will examine the delicate control of this process and how clinicians detect for abnormalities in the heartbeat.