How big is the heart?

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Physical Education - How big is the heart?

How big is the heart?

This depends. Are you a human? Well, then it is generally about the size
of your fist. This is not really very big when you think about the job it
does. In some animals, such as horses, the heart size to body size ratio is
much greater. This helps explain why horses are such great endurance
athletes! The heart is also bigger in champion endurance athletes, due to
genetics and training [1].

In a sense, the heart is really two hearts, the left heart and the right.
Both sides pump the same amount of blood, but to different locations at
different pressures. The right side (right ventricle [2]) pumps
oxygen-depleted blood that has returned from the body to the lungs for
reoxygenation. This is a short trip and requires little pressure
development, so the right ventricle is rather thin walled like a fireplace
bellows. The left side (left ventricle) is the real workhorse, pumping
oxygenated blood that has returned from the lungs (the right and left side
of the heart are thus connected) to the entire body. That means moving
blood through an incredible maze of blood vessels, from the top of the head
to the toes! Consequently it must develop more pressure each beat (about
120mmHg at rest). The left heart muscle is thicker as a result, just as
your bicep would become thicker if you had to lift heavy weights with it
all day.

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Links:
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[1] http://alison.com/#
[2] http://alison.com/#