A major function of the cardiovascular system is to transport fluids. To fulfill this purpose, you have the following structures: The heart, provides pressure to pump the fluids into the large and elastic aorta, which will carry the blood to the body.
The vessels leaving the heart will branch and become smaller in diameter, these are the arteries.
The vessels will continue to branch and get smaller into arterioles. Eventually, they will become the capillaries, which are the sites of gas, nutrient, and waste exchange.