All animals need to (1.)________________ materials around to the different parts of their body. This is the job of the (2.)_____________ system. The circulatory system consists of a liquid called (3.)_______________, a pump called the (4.)________________ and a series of vessels called (5.)____________ and (6.)________________. One thing that must be transported around is a gas called (7.)_____________. Oxygen enters the blood through the (8.)______________. It is then (9.)____________ through the heart and around the body where it is used along with food to make (10.)______________. The body produces another gas called (11.)_______________, which is a waste product. This gas is carried back to the heart and then to the lungs where it is released back into the (12.)_______________.The vessels that transport blood (13.)_________ from the heart are called arteries. The blood in arteries is (14.)_____________ red because it is rich in oxygen. The vessels that transport blood (15.)____________ the heart are called veins. The blood in veins is (16.)______________ red because it is low in oxygen. (17.)________________ are small vessels that join the arteries and veins. (18.)_______________ from food are also transported around the body by the circulatory system. They enter the blood from the small (19.)_________________. The circulatory system also helps to regulate temperature by transporting (20.)_______________ around the body.
