How the Heart Works

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The heart
The heart is one of the most significant organs in the entire human body. It is really nothing more than a pump, collected of muscle which pushes blood throughout the body, beating roughly
72 times per minute of our lives. The heart pumps the blood, which transports all the vital materials which help our bodies function and eliminates the unwanted products that we do not need. For example, the brain needs oxygen and glucose, which, if not received endlessly, will cause it to loose awareness.
Muscles need oxygen, glucose and amino acids, as well as the precise percentage of sodium, calcium and potassium salts in order to contract routinely. The glands need adequate supplies of raw materials from which to manufacture the specific secretions. If the heart ever ceases to pump blood the body begins to shut down and after a very short period of time will expire.

The heart is fundamentally a muscle (a little larger than the fist).
Like any other muscle in 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 power. In skeletal muscles, the distinctive of "gradation" is present. The pumping of the heart is called the Cardiac Cycle, which occurs roughly 72 times per minute. This means that each cycle lasts around eight-tenths of a second. During this cycle the entire heart basically rests for about four-tenths of a second.

Makeup of the Heart

The walls of the heart are made up of three layers, while the cavity is separated into four parts. There are two upper chambers, called the right and left atria, and two lower chambers, called the right and left ventricles. The Right A...

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...ut by the regular age of 70 years, we see that the cardiac output of the normal human heart over a life time would be approximately 1 million litres, or about 250,000 gallons(US)!

Works Cited

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How the Heart Works

1.3 Explain The Cardiac Cycle Essay