The cardiovascular system carries oxygen rich blood to the cells of the body that is used to produce energy. At the center of the cardiovascular system, the heart is a muscle that pumps oxygen rich blood through the body.
The cardiovascular system transports disease fighting white blood cells around the body in order to prevent infection. Nutrients need to make there way to cells around the body, the cardiovascular system transports nutrient rich blood where it is needed. When cells need to dispose of waste, the cardiovascular system carries waste away from cells.
Arteries are tubes in the body that carry blood traveling away from the heart. The walls of arteries are muscular allowing them to help move blood throughout the body.
Veins are tubes that carry blood returning to the heart. The walls of veins are thinner than arteries.
In the heart, chambers called atrium receive blood from the body, while ventricles pump blood away from the heart.
Image: The heart contains blood that has a high level of oxygen (red) and blood that contains a low level of oxygen (blue). Oxygen rich blood is carried to the body, while blood with low oxygen levels travels to the lungs in order to collect more oxygen. Blood in the heart is prevented from mixing by valves.