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| From
the moment your heart begins
beating until the moment it
stops, it works tirelessly without
ever pausing to rest. When you
get right down to it, the heart
is just a pump. A complex and
important one, yes, but still
just a pump providing the power
needed for life. |
|
| How
may times does your heart beat?
|
| The
heart is made of a special type
of muscle that does not become
fatigued. Each heartbeat that
we feel in our chest is one
complete contraction and relaxation
of the heart muscle. The average
heartbeat is 72 times per minute.
In the course of one day it
beats over 100,000 times. In
one year the heart beats almost
38 million times, and by the
time you are 70 years old, on
average, it beats 2.5 billion
times! |
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| How
the Heart Works |
|
The heart is divided into
4 chambers:
|
| |
1- Right Atrium (RA) |
| |
2 -Right
Ventricle (RV) |
| |
3-Left
Atrium (LA) |
| |
4 -Left
Ventricle (LV) |
|
 |
|
| |
5 - Tricuspid
valve - located at the exit of
Right Atrium. |
| |
6 - Pulmonary
valve - located at the exit of
Right
Ventricle. |
| |
7 - Mitral
valve - located at the exit of
Left atrium. |
| |
8 - Aortic
valve - located at the exit of
Left Ventricle. |
|
| Each
chamber has a sort of one-way
valve at its exit that prevents
blood from flowing backwards.
When each chamber contracts
the valve at its exit opens.
When it is finished contracting
the valve closes so that blood
does not flow backwards. |
|
| When
the heart muscle contracts or
beats (called systole) it pumps
blood out of the heart. The
heart contracts in two stages.
In the first stage the Right
and Left Atria contract at the
same time, pumping blood to
the Right and Left Ventricles.
Then the Ventricles contract
together to propel blood out
of the heart. Then the heart
muscle relaxes (called diastole)
before the next heartbeat. This
allows blood to fill up the
heart again. |
|
| The
right and left sides of the
heart have separate functions.
The right side of the heart
collects oxygen-poor blood from
the body and pumps it to the
lungs where it picks up oxygen
and releases carbon dioxide.
The left side of the heart then
collects oxygen rich blood from
the lungs and pumps it to the
body so that the cells throughout
your body have the oxygen they
need to function properly. |
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