The West is blinking in disbelief â Vladimir Putin just invaded Ukraine. German diplomats, French Eurocrats and American pundits are all stunned.
The  circulatory system is the body's transport system. It is made up of a group of organs that transport blood throughout the body. The heart pumps the blood and the arteries and veins transport it. Oxygen-rich blood leaves the left side of the heart and enters the biggest artery, called the aorta.
The largest internal organ is the liver. It is also the heaviest organ, with an average of 1.6 kilograms (3.5 pounds). The largest external organ, which is also the largest organ in general, is the skin. The skin is the largest organ in the human body.