The circulatory system consists of three independent systems that work together: the heart (cardiovascular), lungs (pulmonary), and arteries, veins, coronary and portal vessels (systemic). The system is responsible for the flow of blood, nutrients, oxygen and other gases, and as well as hormones to and from cells.
Blood vessels 
A blood vessel's main function is to transport blood around the body. Blood vessels also play a role in controlling your blood pressure. Blood vessels are found throughout the body. There are five main types of blood vessels: arteries, arterioles, capillaries, venules and veins.
Heart
The human heart is an organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to the tissues and removing carbon dioxide and other wastes
Blood
Blood has three main functions: transport, protection and regulation. Blood transports the following substances: Gases, namely oxygen (O2) and carbon dioxide (CO2), between the lungs and rest of the body