Your circulatory system has three circuits. Blood circulates through your heart and through these circuits in a continuous pattern:
- The pulmonary circuit: This circuit carries blood without oxygen from the heart to the lungs. The pulmonary veins return oxygenated blood to the heart.
- The systemic circuit: In this circuit, blood with oxygen, nutrients and hormones travels from the heart to the rest of the body. In the veins, the blood picks up waste products as the body uses up the oxygen, nutrients and hormones.
- The coronary circuit: Coronary refers to your heart’s arteries. This circuit provides the heart muscle with oxygenated blood. The coronary circuit then returns oxygen-poor blood to the heart’s right upper chamber (atrium) to send to the lungs for oxygen.