TRACE A DROP OF BLOOD THROUGH THE BODY Let’s follow a droplet of blood through the circulatory system. blood is returned to the heart through the largest veins called the and . It enters into the . When this chamber contracts it goes through the valve into the . When this chamber contracts the blood travels through the valve into the which will carry the blood to the . Here it will pick up . The return the blood to the heart where it will enter into the . It is now blood. When this chamber contracts the blood will pass through the or valve into the which is the largest and strongest chamber of the heart. When this chamber contracts, the blood will pass through the valve into the largest artery called the . This vessel will branch off into smaller vessels called which will branch into even smaller vessels which are the . The blood now enters the smallest vessels of the body called where the exchange of gasses, nutrients, and waste products occurs. These vessels will join the smallest vessels of the venous system called which join to form larger vessels called . These vessels join the vena cavae beginning the cycle again.