The |heart| is a hollow pear-shaped muscular organ placed between the |lungs| in the middle of the chest that pumps ~blood~ through the body, supplying cells with oxygen and nutrients. It is attached to the breastbone by special connective tissues called ~ligaments~. The apex (blunt point of the lower edge of the |heart|) lies on the |diaphragm|, pointing toward the left. The apex pulses with every beat of the |heart|. This is what you feel when you hold your hand to your |heart|. The |heart| has four cavities: a small upper cavity (atrium) and a large lower cavity (ventricle) on each side. The adult human |heart| is approximately the size of a fist. In an average adult, it is about five inches long and three and a half inches across at its broadest part, and it weighs less than a pound.
