The heart is a muscular organ composed of four chambers: two atria and two ventricles. The right atrium receives deoxygenated blood from the body and pumps it into the right ventricle, which then sends it to the lungs for oxygenation. The left atrium receives oxygenated blood from the lungs and pumps it into the left ventricle, which then distributes it to the rest of the body. The heart valves (tricuspid, pulmonary, mitral, and aortic) ensure one-way blood flow through the heart chambers.
