The circulatory system is the system made up of heart, blood vessels and blood.
It delivers nutrients and other materials and removes waste products.
The circulatory system consists of:
- tubes: arteries, capillaries and veins
- the heart
- valves 
The human circulatory system is a double circulatory system.
It has two separate circuits and blood passes through the heart twice:
- the pulmonary circuit is between the heart and lungs
- the systemic circuit is between the heart and the other organs
-> Pulmonary circulation takes place between the heart and the lungs
-> Systemic circulation takes place between the heart and other organs