Your heart is your body's pump. In
your lifetime your heart will beat more than two billion times, pumping
about 180 million liters of blood! If you put your two fists together, you
will have the approximate size of a human heart. Your heart is
divided into four chambers; two atria and two ventricles. There is one atrium
and one ventricle on both the right side and the left side of the heart.
When blood flows through your heart, it first flows through an atrium
and then into a ventricle. Within each of the four chambers there
is a valve which allows blood to pass into the next chamber,
or an artery.
The left side of the heart must develop a
pressure that is approximately ten times higher than than the pressure
created on the right side of the heart because it is supplying your
entire body with oxygenated blood. Oxygenated blood is returned to
the left atrium of the heart in the pulmonary veins. Blood then
flows from your left atrium through the mitral valve into your left
ventricle. It is then transported to your body through the aorta,
the largest artery in your body. Because of the pressure it must
maintain to perform its function, the heart valves on the left side of
your heart are most often affected by disease.
After
touring the body, the blood has very little oxygen left. To get a
new supply of oxygen, the deoxygenated blood needs to go to the
lungs. In order to get to the lungs, the blood needs to return to
the heart, entering through the right atrium. The blood is pumped
from the right atrium through the tricuspid valve, pushing the tricuspid
valve's leaflets aside. As the ventricle starts to contract,
drawing in the blood, the tricuspid valve's leaflets snap shut and the
cusps of the pulmonary valve open allowing blood to flow out of the
ventricle through the pulmonary artery and on to the lungs. As the
ventricle relaxes, the pulmonary valve then closes. After leaving the
right ventricle, the blood heads towards the lungs to give up carbon
dioxide and water vapor in exchange for the oxygen the body needs.
It then returns to the heart via the pulmonary veins and enters the left
atrium. Once the blood moves to the left ventricle, it is ready to
start its circuit all over again.
