Overview of the Heart

The heart contains two atria and two ventricles. The right atrium receives oxygen-depleted blood from the body and passes it to the right ventricle, which pumps it to the lungs. The left atrium receives oxygenated blood from the lungs and transfers it to the left ventricle, which pumps blood throughout the body.

Arteries transport oxygen-rich blood from the heart to the rest of the body, while veins carry oxygen-depleted blood back toward the heart. Both connect to capillaries, slender-walled blood vessels that enable gas and nutrient exchange between blood and surrounding tissues.

Heart valves ensure one-way blood flow through the chambers. The tricuspid valve separates the right atrium and ventricle, the pulmonary valve connects the right ventricle to the pulmonary artery, the mitral valve lies between the left atrium and ventricle, and the aortic valve connects the left ventricle to the aorta.

The sinoatrial node in the right atrium acts as the natural pacemaker, initiating electrical impulses that cause the atria to contract. These impulses travel through the atrioventricular node, bundle of His, and Purkinje fibers, triggering ventricular contractions and maintaining the heart's rhythmic pumping action.

The heart pumps blood through the body via the overview of systemic and pulmonary circulation. It maintains constant oxygen and nutrient supply to tissues while removing waste products. This continuous circulation sustains all body functions and is essential for overall health and survival.

The heart is a cone-shaped, hollow muscular organ weighing approximately 250 to 300 grams on average. It measures about 12 centimeters long, 9 centimeters wide, and 6 centimeters thick, making it roughly the size of a closed fist in most adults.

Coronary arteries supply the heart muscle with oxygen-rich blood necessary for its continuous contractions and proper function. When coronary arteries become blocked or narrowed, blood flow is impaired, potentially leading to conditions such as angina and myocardial infarction, which compromise cardiovascular health and function.