How is the function distributed between the respiratory and circulatory systems?

The respiratory and circulatory systems have, so to speak, a common task – to provide the cells and tissues of a living organism with oxygen and purify it from carbon dioxide. But each of these systems, in a single, common process, fulfills its specific function. The respiratory system provides the process of gas exchange in the lungs – external respiration, i.e. absorption of oxygen from the air, saturation of arterial blood with it and the release of carbon dioxide obtained from venous blood. And the circulatory system performs the gas transport function. That is, it delivers oxygen to cells and tissues and carries away from there the product of internal respiration – carbon dioxide.