The circulatory system transports blood throughout the body using the heart and blood vessels. The heart pumps oxygenated blood received from the lungs through arteries and delivers it to tissues via capillaries, where oxygen and nutrients are exchanged. Deoxygenated blood returns to the heart through veins to repeat the cycle. The circulatory system consists of the heart, blood, and a network of arteries, veins, and capillaries.