The system that circulates blood and lymph through the body, consisting of the heart, blood vessels, blood, lymph, and the lymphatic vessels and glands. The Heart The Heart is an amazing organ. The heart beats about 3 BILLION times during an average lifetime. It is a muscle about the size of your fist. The heart is located in the center of your chest slightly to the left. It's job is to pump your blood and keep the blood moving throughout your body. The Blood The blood is an amazing substance that is constantly flowing through our bodies.Your blood is pumped by your heart.Your blood travels through thousands of miles of blood vessels right within your own body.Your blood carries nutrients, water, oxygen and waste products to and from your body cells.A young person has about a gallon of blood. An adult has about 5 quarts.Your blood is not just a red liquid but rather is made up of liquids, solids and small amounts of oxygen and carbon dioxide.