THE
CIRCULATORY SYSTEM \ ALL LIVING cells of the body must have a supply of fuel,
water, and oxy- gen brought to them and must have their waste products removed.
This is the function of the remarkable circulatory system, consisting of the
heart and a vast network of blood vessels. In recent years, much knowledge has
been acquired about the functioning of the human heart and circulatory system
and about factors critical for the health and welfare of the system. There have
been significant developments in the area of prevention of disturbances, and
there are many measures which you can take quite readily.
THE HEART weighing less than a pound when
full grown and only a little larger than your fist, the human heart ranks as
perhaps the world's most fantastic machine. Despite its small size, it beats an
average of 72 times a minute, 100,000 times a day, nearly 40 million times a
year. Each day it pumps the equivalent of some 5,500 quarts of blood weighing 6
tons through more than 60,000 miles of the circulatory system. The work done by
the heart is comparable to the effort you would have to expend to lift a ten-
pound weight three feet off the ground twice a minute for the whole of your
life. A hollow organ, the heart perches in the front part of the chest, under
the breastbone in the center, with its apex pointed to the left. It has a
muscular wall, the myocardium, which is surrounded by a fiber like bag, the'
pericardium, and is lined by a strong, thin membrane, the endo heart is actually ,I double pump, our chambers two at the top called atria and
two at the bottom called ventricles.
