Cardiovascular System


Blood, heart, lung, kidney:
the cycle of life

For thousands of years, the heart has in many cultures symbolised the seat of the soul and centre of the human body. This is hardly surprising, since the beating of the heart is one of the vital signs of life. With every beat of the heart, blood is pumped into the aorta for circulation throughout the body via the arteries.

Thus, oxygen and nutrients reach even the smallest capillary vessels: these constituents are needed in order to sustain the vital functions of the body. At the same time, the blood absorbs metabolic products and carbon dioxide from the tissues. Waste products are filtered out by the kidneys and subsequently removed with the urine.

The carbon dioxide-rich blood flows through the veins back to the heart and is then pumped into the lungs: carbon dioxide is released into the alveoli for 'disposal' via the respiratory air. In parallel, the blood absorbs oxygen and returns to the heart: and so the cycle begins once more.

The interaction of the heart, lung, kidneys and blood ensures that the body is supplied with oxygen and nutrients and is cleansed of metabolic products – hence the foundation is laid for all the organs in the body to function properly. Disturbances to such a complex system can often have far-reaching implications for the entire organism.

The information in this chapter has been compiled from the following sources, among others. Further relevant information can also be found there.

- Global Atlas on Cardiovascular Diseases Prevention and Control, published by the World Health Organization in collaboration with the World Heart Federation and the World Stroke Organization. WHO 2011. ( _diseases/publications/atlas_cvd/en/)

- National Heart, Blood and Lung Institute (

- World Health Organization: Fact Sheets ( factsheets/en/)

- WHO Cardiovascular Disease Website ( diseases/en/)