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Muscle of the Human Body
by Patrick Austin
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| Mr.
Austin is a freelance writer who covers entertainment and
sports for Vainquer magazine, and a multitude of life topics
on PulseMed.org |
The Heart: The Most Important Muscle of the
Human Body
Those obsessed with muscles tend to direct their attention towards
their biceps and triceps. But the heart is by far, the most important
muscle of the human body.
The heart is a pump, composed of muscle which pumps blood throughout
the body, beating approximately seventy-two times per minute.
The heart pumps blood, which carries all the vital materials which
help our bodies function and removes waste products that we do
not need.
For example, the brain requires oxygen and glucose, which, if
not received continuously, will cause it to lose consciousness.
Muscles need oxygen, glucose and amino acids, as well as the proper
ratio of sodium, calcium and potassium salts in order to contract
normally. The glands need sufficient supplies of raw materials
from which to manufacture the specific secretions. Which muscle
of the human body is crucial to all of these functions? The heart,
of course. If it ever ceases to pump blood, the body would begin
to shut down and after a very short period of time…die.
The heart is essentially a muscle(about the size of a fist).
Like any other muscle of the human body, it contracts and expands.
Unlike skeletal muscles, however, the heart works on the "all-or-nothing
law". That is, each time the heart contracts it does so with
all its force.
In skeletal muscles, the principle of "gradation" is
present. The pumping of the heart is called the Cardiac Cycle,
which occurs about seventy-two times per minute. This means that
each cycle lasts about eight-tenths of a second. During this cycle
the entire heart actually rests for about four-tenths of a second.
As you can see, this muscle of the human body is very complex.
The heart is such an important muscle of the human body because
it works as a pump moving blood around in our bodies to nourish
every cell. Used blood, that is blood that has already been to
the cells and has given up its nutrients to them, is drawn from
the body by the right half of the heart, and then sent to the
lungs to be re-oxygenated. Blood that has been re-oxygenated by
the lungs is drawn into the left side of the heart and then pumped
into the blood stream.
It’s the atria that draw the blood from the lungs and body,
and the ventricles that pump it to the lungs and body. The output
of each ventricle per beat is about two tablespoons. In a trained
athlete this amount is nearly double. With the average heart rate
of seventy-two beats per minute the heart will pump about five
liters per ventricle, or about ten liters total per minute. This
is called the cardiac output. In a trained athlete the total cardiac
output is about twenty liters. If we multiply the normal, non-athlete
output by the average age of seventy years, we see that the cardiac
output of the average human heart would be about one million liters,
or about 250,000 gallons. Now you can see why it is the most important
muscle of the human body.
For more information about this muscle of the human body, check
out these sites:
Online
exploration of the human heart—a muscle of the human body
Human heart
information
Human
heart animations and pictures
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