The Cardiovascular System
If the blood vessels of your cardiovascular system were stretched out, they would be 60,000 miles long! That is quite a long journey for your blood to travel, and it requires a strong force to keep it constantly moving. Your heart creates that force without a conscious thought on your part, and it started beating when you were in your mother’s womb.
Why does your heart persistently force your blood through its lengthy, circular voyage? Because blood delivers essential oxygen and nutrients to all of your body’s blood vessels and cells, and removes carbon dioxide and other metabolic wastes from your cells. Round and round your blood goes, thrust through your body with every beat of your heart.