How does the Heart Work?

The adult human hearth is about the size of a clenched fist. Yet it generates enough energy in 24 hours to lift 68,000 kilograms, or the weight of a locomotive, 30 centimeters off the ground. It pumps about 16,360 liters of blood in 24 hours.

This amazing organ, which only weighs 225 to 340 grams, is built like a double-story house. Each part has a room upstairs, the right and left “auricles”, and a room downstairs, the right and left “ventricles”.

There are trap doors called “valves” between the auricle and ventricles into arteries and entrances from veins into the auricles. All the doors in healthy heart fit must not flow back through the same door. The valves open and shut with each heartbeat. 

Actually, the heart is two pump, one on each side. The left side receives the oxygenated blood from the lungs and sends it through the body. The right side receives it back again with less oxygen and more carbon dioxide and sends it to the lungs.

The two upper rooms, the auricles, have thinner walls because they send the blood only a short distance to the lower rooms. The right ventricle has somewhat thicker walls, for it sends the blood to the lungs.

The most important room in the hearth is the left ventricle, with the thickest walls, for it sends the blood farthest. The heart squeezes up and relaxes about 100,000 times each day. In a child it does this from 90 to 100 times a minute; in an adult from 70 to 80 times a minute. When you make some speciall effort, such as running a race, the heart works about three and half times as hard.

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