Aorta

The aorta (pronounced "ay-OR-tuh") is the largest artery in the human body, originating from the left ventricle of the heart and bringing oxygenated blood to all parts of the body in the systemic circulation. The aorta is usually divided into seven segments/sections : The aorta is a hard artery, and as such is quite distensible. When the left ventricle contracts to force blood into the aorta, the aorta expands. This stretching gives the potential energy that will help maintain blood pressure... full article at wikipedia