THE HUMAN HEART
The circulatory system carries vital oxygen, water, nutrients and hormones through our bodies. Our “engine” – the heart – keeps this system running. The fist-sized muscle weighs 300 grams (10.5 ounces) and is located in the center of the chest, slightly to the left, protected by the breastbone (sternum) and ribs. In the span of one minute, the heart pumps all of our blood through the entire body with rhythmic contractions. Over one’s lifetime, the heart beats three billion times and transports 250 million liters of blood – an astonishing performance that no other engine can compete with.