Human Heart

The heart is a muscular organ roughly the size of a fist, located in the thoracic cavity, between the lungs, and behind the sternum. It functions as the central pump of the circulatory system, propelling blood to the lungs for oxygenation and to the rest of the body to supply oxygen and nutrients. The heart consists of four chambers: the right atrium and ventricle, which receive and pump deoxygenated blood to the lungs via the pulmonary circulation, and the left atrium and ventricle, which receive oxygenated blood from the lungs and pump it into systemic circulation through the aorta. The myocardium, the muscular middle layer, contracts rhythmically under autonomic nervous system control, while the endocardium lines the chambers and valves ensure unidirectional blood flow. Electrical impulses originate in the sinoatrial node, spreading through atria and ventricles, regulating heartbeat. Coronary arteries supply the myocardium with oxygen-rich blood, critical for heart function. Disorders such as myocardial infarction, heart failure, and arrhythmias impair the heart's ability to maintain effective circulation. Understanding heart anatomy, physiology, and electrophysiology is vital for medical practice, research, and diagnostics.