READ: Cardiovascular and Respiratory Systems

Cardiovascular System

5. Systems

Two Blood Circulation Systems

The blood is pumped around in two large “loops” within the body. One loop moves blood around the body - to the head, limbs, and internal organs. The other loop moves blood to and from the lungs where carbon dioxide is released and oxygen is picked up by the blood. A simple version of these two “loops” is shown in Figure below.

Systemic circulation is the part of the cardiovascular system that carries oxygen-rich blood away from the heart, to the body, and returns oxygen-poor blood back to the heart. Pulmonary circulation is the part of the cardiovascular system that carries oxygen-poor blood away from the heart to the lungs, and returns oxygen-rich blood back to the heart.


The double circulatory system. Trace the systemic circulation. Where is the path of pulmonary circulation?