The circulatory system transports blood throughout the body using the heart and blood vessels. The human heart has four chambers separated into two sides, with the left side pumping oxygenated blood to the body and the right side pumping deoxygenated blood to the lungs. Blood flows through arteries, capillaries, and veins, with valves in the heart and veins regulating directional flow. The circulatory system delivers oxygen and nutrients to tissues and removes carbon dioxide and waste.