Heart is the centre of life

If one part of your body could be said to be the centre of life, it would have to be your heart.
This organ works steadily all of your life, pumping blood through your whole system.
All parts of your body live because your heart keeps working.
Your heart is a very complicated organ. Actually, it is really two separate pumps in one housing. One side (the left) receives blood from the lungs and pumps it out to all the other parts of your body.
The other side (the right) gets blood back from the body and shoves it out to the lungs.
Consider one side only. Blood flows in through major veins to the upper chamber, the atrium. The blood then flows down into the lower chamber, the ventricle.
Then the upper muscle contracts—forcing more blood into the lower chamber. Blood cannot flow the other way because of a one-way valve which snaps shut.
Now the lower chamber contracts. Blood is forced out and away from the heart.
Again, it cannot flow back because of another one-way valve (the semilunar valve).
This action—the beating of the heart—is automatic and rhythmic. A man’s heart beats about 75-80 times a minute when he is not exercising. A woman’s heartbeat is about 10 beats per minute faster than this.
As a person grows old, their heartbeat slows down somewhat.
What is it that you hear when your heart beats? There are two distinct sounds­—it goes “LUB-dub,” “LUB-dub,” “LUB-dub.”
The first sound is the loudest and longest, and is made by the closing of the valves between the upper and lower chambers.
The second sound (the “dub”) is when the semilunars close between the heart and the arteries.
How does your heart beat so steadily? It is controlled by a bundle of nerve tissue, aptly called the pacemaker. From this centre, nerves spread out to all parts of the heart.
Lots of things will change the rate. Anxiety, fear, excitement, and other emotions will change it. So will some chemicals (nicotine and alcohol, for example).
We all know that exercise will always make our hearts beat faster.
How much blood does your heart pump? Consider both sides of your heart, beating normally, your heart will pump about 11 litres per minute.
For you non-metrics, that’s roughly 2.5 imperial gallons a minute.
If your car has a 20-gallon gas tank, your heart could fill it in about eight minutes.
It works out to the astonishing figure of about 3,600 gallons a day—not bad for a muscle about as big as your fist!
Your heart doesn’t really work all the time. It rests a lot (actually, a bit more than half the time). If you live out your Biblical life span of three score years and 10, then your heart would have rested for nearly 40 of those years.
However, considering that it started working for you more than eight months before you were born, it’s doing a pretty good job for you overall.

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