HOW THE HEART WORKS
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How does the heart work?
The heart is the most important organ in your body. You
cannot live without it. It’s such an important organ that it seems to make its
way into our everyday lives without us even thinking about it. Expressions such
as, “He has a big heart,” “I love you with all my heart,” “I cried my heart
out,” are all expressions that are used to express a deep emotional feeling
whether those feelings be happiness, sadness, or a testament to a person’s
character. The heart is a pump that pushes blood throughout our bodies. Although
that is a very simple explanation of what the heart does, that is the basic
function of the human heart. However, damage to the heart can lead to tragedy
and that is why it’s important to know how your heart works so you can
understand how to best take care of it.
The heart is shaped like a hollow cone. Although
when indicating towards the heart, a person will often point towards the area
just below their left shoulder, the heart is actually located more towards the
middle of the chest. It sits right between the lungs and behind the breastbone.
The portion of the heart that comes to a point at the bottom is called the apex
and that area sits in a lower left position. Even though it is of great
importance, the size of the heart is only about the size of a fist. It weighs
approximately nine ounces for females and 10.5 ounces for males, making up a
total of 0.5 percent of the total body weight.
The heart is comprised of three layers. The
endocardium is the lining inside the heart, the layer that lies in the middle of
the heart is the myocardium and around that is the pericardium, the third layer
of the heart that is a sac that is filled with fluid.
Along with the three layers, there are four
chambers of the heart. These are the right atrium, the right ventricle, the left
atrium and the left ventricle. Beside the top left of the right atrium is the
pulmonary valve and the tricuspid valve sits at the lower left corner of the
right atrium. The mitral valve lies between the left atrium and the left
ventricle and the aortic valve is on the right side of the left atrium. These
valves perform the function of disallowing blood to flow backwards into the
chamber. When the heart beats, the chambers contract and when the chambers
contract, the valves open. Once the chambers have stopped contracting, the
valves close again and no blood is able to get back in.
The contracting of the heart occurs in two stages.
This process, called systole, is comprised of two stages. First, the left and
right atria contract simultaneously and this pumps blood through to the right
and left ventricles. In the second stage, the left and right ventricle contract
to push the blood out of the heart. The heart then relaxes, and this is called
diastole. The motion of the muscle relaxing allows the heart to become full of
blood again and to repeat the process all over again.
The heart is divided into right and left sides
because each side has a different function. The right side of the heart is
responsible for gathering blood inside the body that is deficient in oxygen. The
right side then pumps this blood to the lungs and it is there that the blood
will gather oxygen and in turn, give off carbon dioxide. The left side of the
heart gathers together the blood that has plenty of oxygen in it. It then
distributes that blood to the other cells in the body so the entire body will
have the oxygen it needs for optimum performance.
The blood that enters the heart when the heart relaxes after contracting, goes
into the heart through the right side. It does this by way of two different
veins: the superior vena cava (SVC) and the inferior vena cava (IVC.) The SVC
takes the blood from the upper portion of the body while the IVC takes the blood
from the lower portion of the body. When the blood exits from these two major
veins, it then goes to the right atrium. The contracting of the right atrium
pushes the blood through the triscupid valve and into the right ventricle. As
the right ventricle contracts, the blood is pushed through the pulmonary valve
and into the pulmonary artery where it is then delivered to the lungs.
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