The heart has four chambers, two on the right and two on the left:
- Two upper chambers are called atria (one is an atrium).
- Two lower chambers are called ventricles.
- Tricuspid valve, located between the right atrium and right ventricle
- Pulmonary or pulmonic valve, between the right ventricle and the pulmonary artery
- Mitral valve, between the left atrium and left ventricle
- Aortic valve, between the left ventricle and the aorta
The heart pumps blood to the lungs and to all the body's tissues by a sequence of highly organized contractions of the four chambers. For the heart to function properly, the four chambers must beat in an organized way.