Each day, the average human heart beats
about 100,000 times, pumping 2,000 gallons of blood through the body.
That’s a lot of work for an organ no bigger
than a large fist and weighing 8 to 12 ounces.
In fact, the heart does more physical work
than any other muscle over a lifetime.
Located between the lungs in the middle of
the chest, the heart pumps blood through the network of arteries and veins known
as the cardiovascular system. It pushes blood to the body’s organs,
tissues and cells.
Blood delivers oxygen and nutrients to
every cell and removes the carbon dioxide and other waste products made by
those cells.
Blood is carried from the heart to the rest
of the body through a complex network of arteries, arterioles and capillaries.
Blood is returned to the heart through venules and veins.
The heart is made up of four chambers. The
upper two chambers are called atria (singular: atrium) and the lower two are
known as ventricles (singular: ventricle). Muscular walls,
called septa or septum, divide the heart into two sides.