Heart

The heart is a muscular organ that pumps blood through the circulatory system. Its chambers and valves keep blood moving in an ordered, one-way circuit.

Cardiac cycle: The repeating sequence of heart filling, contraction, and relaxation during one heartbeat. It describes the coordinated events that move blood through the heart.
Cardiac chamber: One of the four hollow spaces in the heart that receives or ejects blood. The two atria and two ventricles divide the heart’s filling and pumping tasks.
Echocardiography: Ultrasound imaging used to examine the heart’s structure and motion. It shows chamber function, valve movement, and blood flow without surgery.
Pulmonary circulation: The circuit that carries blood between the heart and lungs for gas exchange. The right side of the heart sends blood through this circuit.
Cardiac conduction system: Specialized heart tissue that generates and conducts electrical impulses controlling heartbeat. Its signals coordinate the heart’s chambers and set the rhythm of contraction.
Atrium: An upper heart chamber that receives blood returning to the heart. The right and left atria deliver blood to their corresponding ventricles.
Cardiac catheterization: A procedure that guides a thin catheter through blood vessels to examine or treat the heart. It can measure pressures and assess coronary arteries directly.
Systemic circulation: The circuit that carries blood between the heart and the body’s tissues. The left side of the heart supplies this higher-pressure circuit.
Heart valve: A structure that opens and closes to direct blood flow and prevent backflow. The valves enforce one-way flow as pressure changes during each heartbeat.
Ventricle: A lower heart chamber that pumps blood out of the heart. The ventricles provide the force that sends blood to the lungs and body.

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