The circulatory system and immune system serve the same, yet complementary purpose, to keep the entire body alive. The circulatory system does this by delivering oxygen from the lungs to every organ and cell in the body. The immune system does this by consuming foreign substances before they can damage the body. The connection between the circulatory system and immune system lies in the fact that the immune system travels through the entire body, inside the circulatory system.
The circulatory system has three major components: the heart, the lungs, and blood vessels. The lungs absorb oxygen from the air and creates a form of it that passes into the blood stream. The blood vessels then carry this blood through every organ in the body. This is all powered by the heart’s contractions, which provide the force behind the blood’s circulation through the entire body.
Large blood vessels connect the different organ systems. These large vessels split off into a number of smaller vessels, however, that pass through all the tissue in any given organ system. This allows the blood to deliver the lung-created oxygen to all the cells in the body.