The five functions of the human circulatory system are the transportation of hormones, oxygen and nutrients; the removal of waste; the stabilization of the pH of bodily fluids; the maintenance of body temperature; and the fighting of infections. Fighting infections is achieved by transporting white blood cells.
The human circulatory system transports around 2,000 gallons of blood throughout the body daily. This blood is pumped through nearly 60,000 miles of blood vessels. The average adult human has about 5 to 6 quarts of blood, which is made up of red blood cells, plasma, platelets and white blood cells. Besides just moving blood about the body, the circulatory system also helps moves lymph, a clear fluid that helps the body get rid of unwanted material.
The blood vessels, heart and blood make up the cardiovascular component of the human circulatory system. This part of the system includes pulmonary circulation, a loop found in the lungs that oxygenates the blood. The systemic circulation system is also part of the cardiovascular component of the circulatory system. It delivers the oxygenated blood throughout the rest of the body. The pulmonary circulatory system also removes blood that has been depleted of oxygen from the heart and sends it to the lungs.