Heart

Heart

The heart acts as a pump to deliver blood throughout the body. A human adult heart is about the size of a clenched fist. It is located in the center of the chest, and lies just below the second rib. It is muscule and covered in a loose- fitting membrane called the pericardium. The human heart is divided into four chambers; the two upper chambers are called the atria and the two lower chambers are the ventricles. [CG] {NR}