THE HEART
DESCRIPTION:
The heart has four chambers which are the left and
right atria and the left and right ventricles. There are two coronary arteries
that line the surface. The right coronary artery lies between the
right atrium and the right ventricle. It swings around the back of the
heart like a crown. This artery divides into two large branches. The left
coronary artery is larger than the right coronary artery and runs between
the right atrium and ventricle. Then it divides into two branches: the
descending and the transverse arteries. The heart is about the size of
your fist and weighs less than a pound. The heart is located between the
lungs and attached to the breast bone. An adult's heart is five inches
long and three and a half inches wide.
HOW IT WORKS
Your can't control your heart. It works automatically
by beating and is called an involuntary muscle. Flaps in the heart valves
allow the blood to flow in only one direction. The heart makes a sound
like "lub-dub"; that sound is the closing of the valves. The "lub" is the
small push and the "dub" is the big push. The heart beats because of electric
impulses. The heart beats about once a second. If you're in surgery
and doctors are working on your heart, they put you on a special machine
that pumps your blood for you like a robotic heart until the surgery is
done. They do this because your heart can't beat when they're doing surgery
on it. If you watch your heart in motion you will see it fill up like a
balloon and then shrink. That's the blood being pumped out. The aorta is
the biggest and most vital artery in the human body. It takes blood that
is pumped out of the heart to the rest of the circulatory system. It comes
out of the left ventricle. Blood is stopped from reentering the ventricle
by aortic valves which are at the junction of the aorta and the ventricle.
The aorta goes down the spine to the level of the lumbar vertebrae in the
lower back.. There it divides into the common iliac arteries which give
blood to the legs. Doctors like to take peoples blood pressures and
do other tests on the aorta because they tell alot of information
about the heart.
DISEASES
Diseases are common in elderly people. They are
caused by a number things like a broken valve and high blood pressure.
Fatty foods can cause heart disease and coronary artery disease. The more
you eat healthy foods and the more you exercise, the more your body will
feel good. Best of all your heart will feel strong!
REFERENCES
"Body Works." Vers. 4.0. Softkey International, Inc., 1993
"Heart," Microsoft Encarta '95. Edition 95, Microsoft Corp. 1992-1994