Blood circulation
Have you ever been interested in why your heart
actually beats? The process of heart beating is what actually keeps us alive,
so it is quite useful and important to know about it.
The
heart is made up of four different blood-filled areas, and each of these areas
is called a chamber. There are two chambers on each side of the heart: one is
on the top and another is on the bottom. The two chambers on top are called the
atria. The atria are the chambers that fill with the blood returning to the
heart from the body and lungs.
The
two chambers on the bottom are called the ventricles. The heart has a left
ventricle and a right ventricle. Their job is to squirt out the blood to the
body and lungs. Running down the middle of the heart is a thick wall of muscle
called the septum. The septum's job is to separate the left side and the right
side of the heart.
The
atria and ventricles work as a team — the atria fill with blood, then dump it
into the ventricles. The ventricles then squeeze, pumping blood out of the
heart. While the ventricles are squeezing, the atria refill and get ready for
the next contraction. So when the blood gets pumped, how does it know which way
to go?
Well,
your blood relies on four special valves inside the heart. A valve lets
something in and keeps it there by closing — think of walking through a door.
The door shuts behind your blood and keeps it from going backward.
Two
of the heart valves are the mitral valve and the tricuspid valve; they let
blood flow from the atria to the ventricles. The other two are called the
aortic valve and pulmonary valve, and they're in charge of controlling the flow
as the blood leaves the heart. These valves all work to keep the blood flowing
forward. They open up to let the blood move ahead, then they close quickly to
keep the blood from flowing backward.
KAA
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