The transport system is comprised of the heart, blood vessels and blood. The heart function is to pump the blood around the body, through the blood vessels (road for the blood). The transport system operates using a double circulatory system, because the blood travels through the heart twice on one complete journey around the body.
The left side of the heart contains oxygenated blood from the lung. The heart pumps the oxygenated blood around the body, in order to provide each cell with oxygen. Some of the oxygen is used by the cells for respiration. The usage of oxygen by the cells in the body, cause the blood to become deoxygenated. The deoxygenated blood then travels to the right side of the heart and then from there to the lungs to be oxygenated.
When something prevents the transport system from functioning properly, by affecting different components we can refer to those problems as “diseases of the transport system”.