23.1: Overview of the Heart
The heart, a muscular organ located in the chest, functions as the body's pump, circulating blood through the vascular system. It has four chambers: two atria on top and two ventricles below. The right atrium receives deoxygenated blood from the body and passes it to the right ventricle, which pumps it to the lungs for oxygenation. The left atrium receives oxygenated blood from the lungs and transfers it to the left ventricle, which pumps it to the rest of the body.
The heart's structure includes valves that ensure one-way blood flow: the tricuspid valve between the right atrium and right ventricle, the pulmonary valve between the right ventricle and pulmonary artery, the mitral valve between the left atrium and left ventricle and the aortic valve between the left ventricle and aorta.
The heart's electrical system controls its rhythmic contractions. The sinoatrial (SA) node in the right atrium acts as the natural pacemaker, initiating electrical impulses that cause the atria to contract. The impulses travel to the atrioventricular (AV) node through the bundle of His and Purkinje fibers, causing the ventricles to contract.
Coronary arteries supply the heart muscle with oxygen-rich blood. Disorders like coronary artery disease can impair blood flow, leading to conditions such as angina and myocardial infarction (heart attack). Maintaining cardiovascular health is crucial for overall well-being.
