How is the circulatory system is adapted to give oxygen to the tissues and remove waste products?

The circulatory system is described as being "dual", which means that blood passes through the heart twice for each complete circuit of the body, once to the lungs, and once to the rest o fthe body. This has a number of advantages. It allows there to be two separate pressures under which blood is pumped, with a much lower pressure through the lungs, allowing more time for diffusion of gases such as O2 and CO2. The right side of the heart is responsible for pumping to the lungs, via the pulmonary artery (low O2) and then blood returns to the left side via the pulmonary vein (high O2). The large surface area and thin walls of capillaries in both the body and lungs allows a rapid diffusion of gases and metabolites. RBCs contain haemoglobin which vastly increases the ability of the blood to hold O2, and CO2 produced in cells return to the lungs to be exhaled, travelling through veins to prevent backflow.