Intro to the Circulatory System | Biology | Physiology
The circulatory system works to transport oxygen and nutrients to cells in your body, while removing waste products (such as carbon dioxide) at the same time.
This system is actually a double circulatory system, made of two circuits - the pulmonary circuit and the systemic circuit. In the pulmonary circuit, deoxygenated blood is pumped from your heart to your lungs to become oxygenated. In the systemic circuit, this oxygenated blood that is returned to the heart is pumped to the rest of your body.
Unlike other muscles in your body, your heart never tires, and works very hard to ensure that blood reaches all parts, from your head to your toes.