- Two upper chambers of the heart
- Receive blood from the body (right atrium) and lungs (left atrium)
- Push blood into the ventricles during diastole (relaxation phase)
2. Ventricles
- Two lower chambers of the heart
- Pump blood out to the body (right ventricle) and lungs (left ventricle)
- Contract during systole (contraction phase)
3. Valves
- Four valves that control the flow of blood in the heart
- Mitral valve (left atrioventricular valve): between left atrium and left ventricle
- Tricuspid valve (right atrioventricular valve): between right atrium and right ventricle
- Pulmonary valve: between right ventricle and pulmonary artery
- Aortic valve: between left ventricle and aorta
4. Septa
- Two muscular walls that divide the heart into left and right sides
- Atrial septum: separates the two atria
- Ventricular septum: separates the two ventricles
5. Coronary arteries
- Blood vessels that supply the heart muscle with oxygen-rich blood
6. Coronary sinus
- Large vein that collects deoxygenated blood from the heart muscle and empties it into the right atrium
7. Chordae tendineae
- Thin, fibrous cords that connect the heart valves to the papillary muscles
- Prevent the valves from prolapsing back into the atria during systole