A closed system of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products The heart contributes to homeostasis by pumping blood through blood vessels to the tissues of the body to deliver oxygen and nutrients and remove wastes. Blood to reach body cells and exchange materials with them, it must be pumped continuously by the heart through the body’s blood vessels. The heart beats about 100,000 times every day, which adds up to about 35 million beats in a year, and approximately 2.5 billion times in an average lifetime. The left side of the heart pumps blood through an estimated 100,000 km (60,000 mi) of blood vessels, which is equivalent to traveling around the earth’s equator about three times. The right side of the heart pumps blood through the lungs, enabling blood to pick up oxygen and unload carbon dioxide.